OpenAnesthesia: Recent Episodes
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After parenteral injection, sodium nitroprusside enters red blood cells, where it receives an electron from the iron (Fe2+) of oxyhemoglobin. [More]
Acute cyanide toxicity occurs when the cyanide ions bind to tissue cytochrome oxidase and interfere with normal oxygen utilization. [More]
Uterine relaxants may be required to assist in the removal of retained placental products or correction of a uterine inversion. [More]
Nicotine use has several physiologic implications that could potentially impact a patient’s intraoperative course under anesthesia. [More]
Hypotension is a late finding in pediatric patients (children may maintain a normal blood pressure until 35% of blood volume is lost). [More]
Neutral thermal environments (34-35°C or 93.2-95°F) are generally recommended in the context of neonatal resuscitation. [More]
Transmission of signals from nerve to muscle occurs at the neuromuscular junction resulting in contraction of muscle. An action potential is transmitted to the NMJ as the result of depolarization of the nerve. [More]
Myasthenia gravis is an autoimmune neuromuscular disease characterized by skeletal muscle weakness and fatigue. It results from IgG antibodies to the nicotinic acetylcholine receptor (AChR) which results in complement mediated destruction of acetylcholine receptors and membrane architecture at the neuromuscular junction. [More]
Muscle pain is most frequently related to tension, overuse, or muscle injury from exercise or physically demanding work. [More]
Succinylcholine (SCh) is a depolarizing neuromuscular-blocking agent, which produce sustained opening of the nicotinic cholinergic receptor channel. [More]
Rocuronium: elimination half-time increased by 37%. Both volume of distribution and plasma clearance are increased. That said,according to Miller, “the duration of action of single and repeated doses, though, is not significantly affected. [More]
Vecuronium is an intermediate acting nondepolarizing neuromuscular blocking agent of the steroidal compound variety. [More]
The degree of neuromuscular blockade can be monitored in order to determine current depth of blockade, need for further blockade, and to determine need for reversal at the end of a procedure. [More]
The four common side effects/complications include respiratory depression, urinary retention, nausea/vomiting, and pruritus, the most serious being a dose-dependent, delayed respiratory depression. [More]
According to Miller, “the analgesic effects of opioids arise from their ability to directly inhibit ascending transmission of nociceptive information from the spinal cord dorsal horn and to activate pain control circuits that descend from the midbrain, via the rostral ventromedial medulla (RVM) [More]
One lead of the low-output nerve stimulator is attached to a needle and the other lead is grounded somewhere on the patient. Lower current is required when a negative lead is attached to the needle. [More]
February 2023: Dr. Tricia Vecchione and OpenAnesthesia Associate Editor, Dr. Elisha Peterson, discuss an update on pediatric regional anesthesia.
https://traffic.libsyn.com/secure/openanesthesia/OA-SPA_Ask_the_Expert_February2023__Vecchione.mp3
Lower Extremity
Femoral
- Below inguinal ligament
- 1 cm lateral to femoral artery
- At level of femoral crease
[More]
Sodium and Potassium in the resting cell: The resting cell has an electrical potential-resting membrane potential- approximately -60 to -70mV in neurons (0 is convention for extracellular potential). Neurons at rest are more permeable to K+ ions than Na+ ions because of K+ leak channels; thus, membrane potential is closer to equilibrium potential of K+ (Ek+ -80 mV, eNa+ +60mV). [More]
Side effects of anticholinesterases include bradycardia, hypotension, bronchospasm (and hypoxia), increased respiratory secretions, possibly nausea and vomiting (although this is controversial and, according to Miller (1), “Reports on the effect of anticholinesterase administration on postoperative nausea and vomiting are conflicting “), increased GI motility and secretions, miosis, and decreased intraocular pressure. [More]
When neostigmine is administered to reverse neuromuscular blockade (NMB), the nicotinic effects are desired but muscarinic effects can be problematic. [More]
OpenAnesthesia Associate Editor Dr. Beti Asnake sits down with Dr. Tirunesh Busha, one of three pediatric anesthesiologists in Ethiopia, to discuss her career, challenges in the provision of anesthetic care in Ethiopia and her interest in pediatric anesthesiology.
https://traffic.libsyn.com/secure/openanesthesia/January_2023_OA-SPA_Ask_the_Expert_Busha.mp3
For Neostigmine a maximum dosage is in the range of 60 to 80 mcg/kg. Although large doses of the drug will result in more rapid antagonism, there seems to be a “ceiling effect”. The maximum effective dose, beyond which further amounts of anticholinesterase will not produce any greater antagonism. [More]
The development of postoperative apnea is a major concern with surgery in neonates. Infants at highest risk are those born prematurely, those with multiple congenital anomalies, those with a history of apnea and bradycardia, and those with chronic lung disease. [More]
Neonatal cardiac physiology differs from that of the adult in several ways. At birth, the neonatal myocyte is not fully developed; making the heart less able to respond to volume loading with an increased cardiac output. [More]
This is a repost of the September 2018 episode with Dr. Adrian T. Bosenberg and OpenAnesthesia Editor Dr. Faith Ross, who discussed the topic of pediatric regional anesthesia. This topic will be updated in the February 2023 episode by OpenAnesthesia Associate Editor, Dr. Elisha Peterson who interviews Dr. Tricia Vecchione on this topic.
https://traffic.libsyn.com/secure/openanesthesia/repost201809Bosenberg.m4a.mp3
Drugs are rarely indicated in resuscitation of the newly born infant. Bradycardia in the newborn infant is usually the result of inadequate lung inflation or profound hypoxemia, and establishing adequate ventilation is the most important step toward correcting it. [More]
CPAP (Continous Positive Airway Pressure) provides continuous positive pressure which helps minimize atalectasis and maintain recruitment. In neonates, FRC is lower and closing volume (volume at which terminal airways are no longer open) is higher than in adults. Therefore CPAP is quite effective. [More]
Neonatal hypoxemia is an inadequate oxygen level in the neonate to meet its metabolic demands. This may be different levels of oxygen depending on the age of the neonate. [More]
Neonatal bradycardia is defined as a decrease in heart by 30 bpm from baseline. Regarding neonatal resuscitation, bradycardia is concerning when the heart rate is less than 100 bpm. The primary cause of neonatal bradycardia is hypoxia. [More]
Negative pressure pulmonary edema (NPPE) is an uncommon complication of anesthesia usually resulting from laryngospasm during extubation (approximately 0.1%). [More]
Central line placement: Internal jugular vein
Both the National Institute of Clinical Excellence and the CDC recommended ultrasound guidance for central venous line (CVL) placement for those who have training in using the technology. [More]
Lasers are devices that emit a single, coherent wavelength of electromagnetic radiation that is used to cut, coagulate or ablate tissue for a variety of clinical applications. [More]
Nasal FOI can be done both awake and under general anesthesia.
Awake Nasal FOI
As with oral FOI, the key to success in an awake nasal fiberoptic intubation is adequate topical anesthesia. (And, as with anything in anesthesia, there is more than one way to do this procedure.) [More]
Nalbuphine, 10 mg IM, produces analgesia with an onset of effect and duration similar to morphine. Depression of ventilation is similar to morphine until 30 mg IM of nalbuphine is exceeded, after which no further depression of ventilation occurs (ceiling effect). [More]
The neuromuscular junction is the connection point between motor nerve endings and post-junctional skeletal muscle. [More]
The neuromuscular junction is composed of the axon terminal of a motor neuron and the motor end-plate of the receiving muscle cell membrane, separated by the synaptic cleft. [More]
According to Miller, “In conditions associated with insulin resistance, there seems to be a proliferation of AChRs beyond the junctional area… the extrajunctional immature receptors can reappear soon after upper and lower motor denervation and in certain pathologic states (e.g., burns, immobilization, chronic muscle relaxant therapy, loss of electrical activity).” [More]
Nondepolarizing neuromuscular blocking agents (NMBAs) are commonly used medications in the operating room. By competing with acetylcholine, these drugs bind to alpha subunits on nicotinic acetylcholine receptors to produce their effects. [More]
Neuromuscular blocking agents exert their effects at the neuromuscular junction (motor end plate). To understand how they work, it is important to first understand the anatomy of a single motor end plate. [More]
Halogenated volatile anesthetics have a potentiating effect on nondepolarizing muscle relaxants . The mechanism appears to be incompletely understood, but is likely a combination of: [More]
Peripheral nerve stimulators are theoretically the most reliable monitoring method, although visual estimates of TOF are unreliable. [More]
Lambert-Eaton syndrome is a paraneoplastic syndrome characterized by proximal muscle weakness that typically begins in the lower extremities but may spread to involve upper limb, bulbar, and respiratory muscles. [More]
Hyperparathyroidism (HPT) is a common cause of hypercalcemia and the effects of calcium at the neuromuscular junction may cause pre-existing muscle weakness. [More]
The neuromuscular junction (NMJ) is the synapse (junction) between the axon terminal of a motor neuron and the motor end-plate. [More]
Greater than 200,000 health care professionals are exposed to anesthetic gas waste and are at risk of occupational illness. Through improvements in scavenging systems, more effective ventilation systems, an increased attention to equipment maintenance and leak detection, and careful anesthetic practices, there have been significant improvements in minimizing anesthetic gas pollution; however, occupational gas waste exposure still exists. [More]
Entrance of nitrous oxide into cavities filled with gas (ex. bowel) can lead to an increase in pressure. After intravitreal injection of sulfur hexafluoride (colorless, odorless, non-flammable gas) or perfluoropropane (C3F8), nitrous oxide may increase intraocular pressure. [More]
It is characterized by muscle wasting (muscular dystrophy), cataracts, mental retardation, heart conduction defects, endocrine changes, and myotonia (delayed muscle relaxation following contraction). [More]
Myotonic dystrophy (MD) is a muscular disorder characterized by prolonged contraction and delay of relaxation of muscles, progressive muscle weakness, and wasting. Incidence is 1 in 8000. [More]
Myotonic dystrophy (dystrophia myotonica, DM) is a muscular disorder characterized by prolonged contraction and muscle relaxation, progressive muscle weakness, and wasting. [More]
Diagnosis of myofascial pain is made by palpation of trigger points reproducing pain that is characterized as explicitly tender and narrowly localized, aching and lingering associated with stiffness, muscle spasm or muscle weakness as well as some degree of autonomic dysfunction. [More]
An axillary block is often used for forearm or hand surgery. Local anesthetic is injected around the axillary artery, as the nerves of interest lie in close proximity. The patient is positioned in the supin position with the arm abducted 90°. The ultra sound probe is placed just distal to the bicipital grove, where the pectoralis major muscle inserts. The probe is placed in the short-axis orientation.
The axillary artery (AA) is identified as pulsatile and generally, non-compressible, with the axillary vein often running medial to it. The median nerve (MN) lies superficial and lateral to the AA. The ulnar nerve (UN) lies posterior to the AA. The radial nerve (RN) lies posterior to the AA and either medial or lateral. A second injection is made to block the musculocutaneous nerve located between the biceps muscle and coracobrachialis muscles, identified as an elongated oval.
The radial nerve innervates the dorsal surface of the first 3½ digits and this portion of the dorsal hand leading to the first 3½ digits, the triceps muscle, and the extensor muscles of the hand.
The ulnar nerve innervates the superficial, anterior and posterior portion of the last 1 ½ digits and the portion of the dorsal and palmar surface proximal to the last 1½ digits.
The median nerve innervates the anterior portion of the first 3½ digits and the palm leading to these 3½ digits, most of the sensory innervations of the palm.
The musculocutaneous nerve innervates the biceps, coracobrachialis and brachialis muscle.
SourcesThe New York School of Regional Anesthesia: Ultrasound-Guided Axillary Brachial Plexus Block, accessed 12/20/22.
Miller RD, Pardo M. Basics of Anesthesia, 6th ed. Philadelphia, PA: Elsevier Saunders; 2011: pp 287-292.
For skeletal muscle, Na+ mediated depolarization (Phase 1) is quickly followed by repolarization (Phase 3). Repolarization is mediated by closure of the Na+ channels responsible for depolarization, and opening of voltage-gated K+ rectifier channels, which allows for potassium efflux. [More]
Caused by papillary rupture, acute MR can present itself with the following symptoms and signs. [More]
The amount of oxygen consumed is determined by the basal O2 consumption, wall tension, contractility and heart rate. [More]
A Myelomeningocele results from an abnormality in fusion of the embryologic neural tube during the first month of gestation. [More]
Myasthenic syndrome and myasthenia gravis are two disorders of neuromuscular transmission that result in muscle weakness and fatigue. [More]
Myasthenia includes three groups of autoimmune disorders (Myasthenia Gravis, Congenital myasthenic syndromes, Lambert-Eaton myasthenic syndromes) that affect the transmission of signals at the neuromuscular junctions that results in weakness and muscle fatigueability. [More]
Myasthenia gravis is caused by IgG antibodies to nicotinic ACh receptors. Most patients are on anticholinesterases, but may progress to steroids, thymectomy, immunosuppression, and plasmapheresis depending on the severity of the disease. IV immunoglobulin can be used for acute exacerbations. [More]
Myasthenia gravis is an autoimmune disease that attacks post-synaptic nicotinic acetylcholine receptors at the NMJ. [More]
In the resting state, the electrical potential of the inside of a nerve cell is negative with respect with the outside. [More]
In general, antibiotics as a class potentiate both depolarizing muscular blocking drugs and nondepolarizing neuromuscular blocking drugs to varying degrees. [More]
In the perioperative setting, benzodiazepines are frequently used for anxiolysis, amnesia, and sedation. They exert these effects via the gamma-aminobutyric acid (GABA) neurotransmitter system. [More]
Multiple Sclerosis is an autoimmune disease of inflammation, demyelination, and axonal damage to the central nervous system (Pasternak, 2008; Dorotta, 2002). [More]
Morphine is a prototype opioid that is less lipophilic (less blood-brain barrier penetration) than the synthetic opioids and therefore has a slower onset of action (within 20 minutes) but a longer analgesic duration (4 to 6 hours and up to 7 hours for morphine-6-glucoronide). [More]
Several factors contribute to the fact that morbidly obese patients are more prone to rapidly desaturate when apneic. [More]
Morbid obesity can be defined by a BMI > 40, or BMI > 35 with comorbid diseases such as DM and hypertension. [More]
Barbiturate coma therapy has been used in head injured patients to lower ICP when other therapies such as mannitol and hyperventilation have failed. [More]
The general hemodynamic goal in treating mitral insufficiency is to preserve forward flow (and reduce regurgitant flow). [More]
Equilibrium: State in which constant amount of molecules jump from the liquid phase to gas phase and vise versa. [More]
Bypyridine derivative, isoenzyme fraction PDE III inhibitor. This inhibition decreases the hydrolysis of cAMP, leading to increased intracellular concentration of cAMP in the myocardium and vascular smooth muscle. [More]
Pediatric oral dose is 0.5 mg/kg. According to Smith’s Anesthesia (Ch. 7), times for peak serum concentrations after intramuscular, rectal, and oral administration were 15, 30, and 53 minutes, respectively, whereas the drug clearance and bioavailability via these three different routes were 10.4, 50.8, and 33.4 mL/kg per minute and 87%, 18%, and 27%, respectively. […]
November 2022: Dr. Elizabeth Hansen and OpenAnesthesia Editor Dr. Aditee Ambardekar discuss the impact of anesthetic gases on the environment and greening the operating room.
Drug Category : PDE inhibitor Mechanism : Causes direct stimulation of myocardial contractility and acceleration of myocardial relaxation. [More]
Bioavailability of IM, rectal, and PO routes are 87, 18, and 27%, respectively. According to Smith’s Anesthesia (Chapter 7), “times for peak serum concentrations after intramuscular, rectal, and oral administration were 15, 30, and 53 minutes, respectively … [More]
Wolff–Parkinson–White syndrome (WPW) is a ventricular pre-excitation syndrome associated with abnormal conduction pathways between the atria and ventricle. [More]
At the turn of the 20th century, Meyer and Overton independently discovered the correlation between lipid solubility and anesthetic potency. [More]
Metoclopramide is both a dopaminergic receptor antagonist and a selective peripheral cholinergic agonist. The antiemetic effect is attributed to the central and peripheral dopamine receptor inhibition. [More]
Numerous systems in the body produce signals to induce vomiting. Some of these systems include the cerebral cortex, vestibular system, and GI tract. [More]
Methemoglobin (MetHb) is altered state of hemoglobin (Hb) in which the ferrous (Fe2+) irons of heme are oxidized to the ferric (Fe3+) state. The ferric hemes of MetHb are UNABLE to bind oxygen (O2). Thus, oxygen dissociation curve is left-shifted, making it more difficult to release O2. [More]
Methemoglobin (MetHb) is altered state of hemoglobin (Hb) in which the ferrous (Fe2+) irons of heme are oxidized to the ferric (Fe3+) state. The ferric hemes of MetHb are UNABLE to bind oxygen (O2). Thus, oxygen dissociation curve is left-shifted, making it more difficult to release O2. [More]
There is an FDA Black Box Warning on methadone which states, “In addition, cases of QT interval prolongation and serious arrhythmia (torsades de points) have been observed during treatment with methadone. Most cases involve patents being treated for pain with large, multiple daily doses of methadone, although cases have been reported in patients receiving doses […]
Together, can cause lactic acidosis However, this rare complication occurs only if the contrast medium causes renal failure, and the patient continues to take metformin in the presence of renal failure. [More]
Meperidine is a synthetic opioid widely used for treating pain. It is also used for controlling post anesthetic shivering. Its main pharmacological action is produced through μ receptors on the central nervous system (CNS). [More]
Metabolic alkalosis is a very common primary acid–base disturbance associated with increased plasma HCO3. Increased extracellular HCO3 is due to net loss of H+ and/or addition of HCO3. [More]
Metabolic acidosis refers to the increased hydrogen ion concentration and decreased bicarbonate that can result from one of three abnormalities: 1) Increased generation of acid, 2) Decreased excretion of acid, or 3) Loss of bicarbonate. [More]
Arnold Chiari Malformation or Chiari II (CMII) is uniquely associated with myelomeningocele. Chiari II malformation is defined as the caudal herniation of the vermis, brainstem, and fourth ventricle through the foramen magnum. [More]
According to the Agency for Healthcare Research and Quality (AHRQ), an adverse drug event is defined as harm experienced by a patient as a result of exposure to a medication. Adverse drug events may affect as many as 5% of hospitalized patients. [More]
Mediastinoscopy provides access to the mediastinal lymph nodes and is used to establish either the diagnosis or the resectability of intrathoracic malignancies. [More]
Mediastinal masses present special anesthetic considerations, as they can be associated with hemodynamic compromise from pulmonary artery and cardiac compression, neurologic problems (increased ICP, headache, and altered mental status) from obstructed venous drainage in the upper thorax (i.e. superior vena cava syndrome), or respiratory compromise from airway obstruction and loss of lung volumes. [More]
There are several factors that influence vasoconstriction of the cerebral vascular bed. Perhaps the most notable is the carbon dioxide (PaCO2). [More]
Cytochrome P450 (CYP) is a membrane bound protein present in most tissues in the body. It is a member of a superfamily of proteins known as hemoproteins – those that contain a heme group that is active in the catalytic mechanism of these various proteins. [More]
EBV calculation: body wt (kg) x average blood volume (ml/kg) ABL= [EBV x (Hi-Hf)]/Hi [More]
Maternal mortality is higher for women >35 years old, black patients, and patients without prenatal care. [More]
Gas Exchange Gas Exchange: improves oxygenation by re-expanding collapsed alveoli (reduced shunt ) and redistributing lung water from alveolar to interstitial space, both improve V/Q matching. If too high could hyperinflate impairing blood flow increasing deadspace lowering PaO2 raising PaCO2. [More]
Mannitol is an osmotic diuretic that is a six-carbon carbohydrate that undergoes filtration at the glomerulus with limited or no reabsorption in the proximal tubules. [More]
Pre-Hospital Management of Acute Heart Failure EKG, spot BNP. Non-Invasive Positive Pressure Ventilation (NIPPV) for any patient in acute pulmonary edema. [More]
The Mallampati score was developed by Seshagiri Mallampati, an American anesthesiologist, in 1985 as a non-invasive way to assess the airway. It is a visual examination that compares the size of the tongue to the size of the oral cavity. [More]
Central Core Disease is most associated w/ MH. More than Duchenne Muscular Dystrophy. Central Core Disease comes from a disorder on the same gene, RYR1 on chromosome 19. MD is x-linked recessive, risk for hyperK w/ sux leading to fatal Rhabdomolysis. [More]
Malignant hyperthermia (MH) is an autosomal dominant pharmacogenetic syndrome triggered by halogenated volatile anesthetic gases and succinylcholine. [More]
Magnesium sulfate is used as a tocolytic and anticonvulsant in parturient patients with preeclampsa/eclampsia. Although it is a very effective medication in this setting it has severe adverse effects at supratherapeutic levels requiring regular monitoring of the patient for sign/symptoms of magnesium toxicity. [More]
In vascular smooth muscle cells magnesium acts intracellularly and extracellularly as a calcium antagonist to inhibit contractility. [More]
• Cardiac arrest • Pulmonary edema (lungs fill with fluid; can be fatal) • Chest pain [More]
Signs of malignant hyperthermia include increased CO2 production or minute ventilation, increased O2 consumption, increased cardiac output, increased HR, increased BP, arrhythmias, rigidity, and temperature elevation. [More]
The original antidepressants, phenelzine (Nardil), isocarboxazid (Marplan), and tranylcypromine (Parnate) are all irreversible inhibitors of MAO-A and MAO-B, leading to pronounced effects on metabolism of endogenous (5-HT, NE, and DA) and exogenous (tyramine) monoamines. [More]
October 2022: Dr. Titi Aina and OpenAnesthesia Editor Dr. Elisha Peterson discuss global health in anesthesia.
Lusitropy refers to the ability of the myocardium to relax following excitation contraction coupling. The removal of calcium to the endoplasmic reticulum (SR) promotes relaxation. [More]
Patients with a VO2 max < 10 mL/kg/min are at very high risk [Bechard D et al. Ann Thorac Surg 44: 344, 1987; Bollinger CT et al. Chest 108: 341, 1995], and 15 mL/kg/min may be a reasonable cutoff [Miller’s Anesthesia, 7th ed. 2009. p 1821] Stair climbing is a reasonable alternative (five flights = […]
Patients with ARDS (PaO2/FiO2 < 300, bilateral pulmonary infiltrates on a CXR, no clinical evidence of left atrial hypertension or if measured a wedge < 18 mm Hg, excluding all patients with elevated ICP, neuromuscular, sickle cell, or severe chronic respiratory disease, obesity > 1 kg/cm height, or burns > 30% of BSA). . . […]
Compliance is defined as change in volume divided by change in pressure (C = dV/dP or ∆V/∆P). Normal compliance in healthy lungs is ~ 0.2-0.3L/cmH2O. [More]
Conservative treatment is appropriate for most patients. This may include anti-inflammatory medications, physical therapy or chiropractic treatment, and avoiding activity that strains the neck or back. [More]
The lower extremity sensation is provided mainly by two major nerves: the sciatic (posterior) and femoral (anterior) nerves. [More]
Lorazepam is a benzodiazepine that works through activation of GABAA to increase the activity of GABA which in turn reduces neuronal firing in the brain. [More]
Definition: Tidal Volume (Vt) 4-7 cc/kg predicted body weight, i.e., [50 (male) OR 45 (female) +0.91(ht in cm – 152.4)] [More]
Regression analysis is concerned with relationship between two or more variables. There are many subtypes of regression depending on the variables to be studied and the nature of the relationship of interest. [More]
Local anesthetic toxicity can be seen in organs of the body that depend upon sodium channels for proper functioning. These include the central nervous system and heart. The CNS is more sensitive to the effects of local anesthetics than the cardiac system and will generally manifest signs/symptoms of toxicity first. [More]
Lidocaine was first used as a spinal anesthetic in 1948. In 1991, case reports of cauda equina syndrome began to appear following the use of 5% lidocaine through microcatheters. Two years later, in 1993, transient neurologic symptoms (TNS), was described. [More]
Methemoglobinemia can occur following use or prilocaine in adults. In adults, the toxic dose is ~ 600 mg IV. [More]
The onset of local anesthetics are dependent on the anesthetic technique utilized. The shortest onset time is encountered after intrathecal or subcutaneous administration, the longest occurs with peripheral nerve blocks. [More]
According to Miller, “Abnormalities in sodium electrolyte levels are frequently observed and are often related to volume status and sodium retention; these abnormalities can result in either hyponatremia or hypernatremia“. Other common abnormalities in ESLD include hyperkalemia, hypokalemia, and hypomagnesemia. [More]
The liver is responsible for synthesizing different proteins. In advanced liver disease, the creation of these proteins is impaired and can be measured with the following lab tests…[More]
Most commonly injured lower extremity nerve in patients undergoing surgery in lithotomy position was the common peroneal nerve (L4-S2, represented 78% of nerve injuries in a study which looked retrospectively at 198,461 patients undergoing surgery in the lithotomy position). [More…]
Lithium is a commonly used mood stabilizing drug. One of lithium’s proposed mechanisms of action is a reduction in the release of neurotransmitters in the central nervous system (CNS) and peripheral nervous system (PNS) which also may lead to many of its adverse side effects and anesthetic interactions. [More…]
Lithium salts (most commonly, lithium carbonate) are frequently used to treat bipolar disorder. According to experimental animal data and case reports in humans, lithium can interfere with anesthetic agents and neuromuscular blockers. [More…]
Introduction and Controversy Introduction to Liposuction and Tumescent Fluid Howard Solbel, in an editor’s response to Yoho’s article (see below), state the following – “Let us first understand the difference between the tumescent technique and the tumescent solution. [More…]
This is a repost of the October 2019 episode with Drs. Mark Newton and OpenAnesthesia Editor Aditee Ambardekar who discuss the topic of global health. This topic will be updated in the October 2022 episode.
Intro: Electrocution To receive a shock, persons need body contact with two separate conductive materials at different voltage potentials to complete a circuit. [More…]
According to the ASA Continuum of Depth of Sedation, the levels of sedation/analgesia are separated into 4 categories based on responsiveness, airway patency, adequacy of spontaneous ventilation, and cardiovascular function. [More…]
Donor leukocytes (from pRBCs or platelets) are associated with potential adverse reactions. First of all, their HLA surface antigens are main targets of the recipient’s immune system and can cause febrile transfusion reactions in the recipients. Furthermore, some viruses such as CMV, HTLV 1, and EBV are transmitted in donor leukocytes. [More…]
There are particular foods and fruits that are known to produce a type of substance that is similar to the rubber latex. This is known as the latex-fruit syndrome. [More…]
Latex is a naturally occurring compound, derived from tree sap, and used to make rubber products. The first allergic reaction to latex was reported in 1979. [More…]
The lateral femoral cutaneous nerve (LFCN) divides into several branches that innervate the lateral and superior aspects of the thigh. [More…]
Incidence of airway fire during laser surgery is traditionally quoted to be ~ 1%, although a large retrospective series of CO2 laser suggested that it may be closer to 0.1%. [More…]
Laryngospasm treatment mandates immediate removal of the offending stimululs (suctioning) as well as the near-simultaneous application of 100% oxygen and positive pressure ventilation (to stent open the airway). [More…]
Laryngospasm: Stimulation of vagus nerve during light anesthesia (Superior Laryngeal n, pharyngeal br of vagus, recurrent laryngeal below cords). [More…]
Laryngospasm is most commonly caused by anything that irritates the larynx, including secretions, blood, or debris. [More…]
Grade I – full view of glottis (can see 100% of black hole) Grade 2a – partial view of glottis (can less than 100% of black hole) [More…]
The recurrent laryngeal nerve (RLN) and the superior laryngeal nerve (SLN) are branches of the vagus nerve (CN X). [More…]
CO2 Subcutaneous Emphysema Occurs with insufflation of the extraperitoneal space. May be accidental or intentional. [More…]
Myasthenic Syndrome (Lambert-Eaton) is caused by IgG antibodies to voltage-gated Ca++ channels in the musculature, which leads to increased sensitivity to both SCh and nondepolarizing muscle relaxants. [More…]
Lactated Ringer’s (LR) is a slightly hypotonic balanced crystalloid solution used in electrolyte replacement and volume resuscitation. [More…]
1st Stage of Labor Pain is dull and poorly localized. Uterine contractions release bradykinin, histamine, and serotonin that act on chemoreceptors. [More…]
Labetalol is a mixed adrenergic blocker that blocks alpha-1, beta-1 and beta-2 adrenergic receptors. Administration results in decreased peripheral vascular resistance and mean arterial pressure without significant changes in heart rate and cardiac output. [More…]
Muscle metabolism –> creatine –> creatinine (nonenzymatically converted). Creatinine production is constant, related to muscle mass (20-25 mg/kg males, 15-20 mg/kg females). [More…]
Filling occurs during diastole, which has 4 phases: (1) isovolumic relaxation; (2) rapid filling phase; (3) slow filling, or diastasis; and (4) final filling during atrial systole (atrial kick.) [More…]
LMWH binds to anti-thrombin, a serine protease inhibitor, and creates a conformational change. This change accelerates its inhibition of activated factor X in conversion of prothrombin to thrombin. [More…]
Indications for use: The LMA device is appropriate for elective cases, as a rescue device, in expected difficult airway situations or in fasting patients. It can be used in CPR situations if the patient is profoundly unresponsive. [More…]
August 2022: Dr. Mary Lyn Stein and OpenAnesthesia Editor Dr. Jina Sinskey discuss an update on the topic of pediatric difficult airway.
This is a repost of the July 2018 episode with Drs. John Fiadjoe and OpenAnesthesia Editor Aditee Ambardekar who discuss the topic of pediatric difficult airway. This topic will be updated in the August 2022 episode!
Deoxygenated blood can carry increasing amounts of carbon dioxide, whereas oxygenated blood has a reduced carbon dioxide capacity. [More…]
Hypertensive disorders are one of the leading causes of maternal mortality worldwide. Blood pressure typically falls early in pregnancy and reaches nadir between 16-20 weeks gestational age. Later in pregnancy, the blood pressure will return to baseline. [More…]
Hypoxic pulmonary vasoconstriction (HPV) is a physiologic mechanism by which lung perfusion is adjusted to match ventilation through the contraction of vascular smooth muscle in the pulmonary circulation in response to low regional partial pressure of oxygen. [More…]
In patients with HOCM, systolic septal bulging into the LVOT, malposition of the anterior papillary muscle, drag forces, and hyperdynamic LV contraction (causing a Venturi effect) may contribute to creation of a LVOT gradient. [More…]
After inoculation, patients will often experience a flu-like illness. Over the first 4-8 weeks, patients have significant viremia with a drop in CD4+ cell count with a drop in virema and an increase in CD4+ cell count by the end of the first 4-8 weeks. [More…]
The Health Insurance Portability and Accountability Act of 1996 (HIPAA) includes Standards for Privacy of Individually Identifiable Health Information (“Privacy Rule”). [More…]
Hydrochlorothiazide is a sulfonamide derivative. It blocks the Na/Cl co-transporter in the early segment of the distal convoluted tubule. [More…]
Guillain-Barre Syndrome is characterized as an acute inflammatory demyelinating peripheral polyneuropathy secondary to an autoimmune response in association with an infectious process. [More…]
The Glasgow coma scale is an assessment tool utilized to measure level of consciousness after brain injury. GCS
In simple terms, pharmacokinetics describes “what the body does to a drug,” whereas pharmacodynamics describes “what the drug does to the body.” [More…]
According to Miller, age does not significantly affect the pharmacodynamics of muscle relaxants… Duration of action may be prolonged, however, if the drug depends on liver or renal metabolism. [More…]
The minimum alveolar concentration (MAC) of inhaled anesthetics decreases with age. For every decade of life after age 20, the MAC is reduced by ~6%. [More…]
June 2022: Dr. Ravi Shah and OpenAnesthesia Editor Dr. Elisha Peterson discuss an update on the topic of the opioid epidemic and children. See also the companion episode from May 2018 in which Drs. Chatterjee and Yaster discuss the same topic.
Elderly lungs lose tissue elasticity and demonstrate increases in lung compliance (much like emphysema), however, chest wall compliance decreases, so the net pulmonary compliance is virtually unchanged. [More…]
Age-related changes in the elderly include a decrease in muscle mass and an increase in body fat, resulting in a reduction in total body water. This leads to a decreased volume of distribution for water-soluble drugs, causing an increase in plasma concentration. [More…]
losure of the abdominal wall defect in gastroschisis can cause decreased diaphragmatic excursion and compression of the lungs, with the development of abdominal compartment syndrome (ACS). Pulmonary compliance decreases, and an increase in airway pressures can be seen during positive pressure ventilation. [More…]
As a companion episode to the the June 2022 episode, we are reporting the May 2018 episode with Dr. Myron Yaster and OpenAnesthesia Editor Dr. Debnath Chatterjee who discuss the opioid epidemic and pediatric anesthesia.
Classically it has been taught that patients who are at a higher risk of aspiration include those who have a “full stomach,” diabetic patients, patients with hiatal hernia or GERD, patients with cirrhosis, patients with significant ESRD, and pregnant patients. [More…]
Preoperative fasting is used to reduce the risk of pulmonary aspiration. From the ASA guidelines on preoperative fasting, meta-analysis of randomized controlled trials demonstrated in adult patients given clear liquids 2-4 hours before a procedure versus 4 hours had smaller gastric volumes and higher pH values. [More…]
Gas Laws: temperature/pressure changes PV=NRT where k is the Boltzmann constant. [More…]
The Glasgow Coma Scale (GCS) is a neurological scoring system introduced in 1974 that was designed to be used to assess and document neurologic function after head injury. [More…]
Furosemide is a loop diuretic that inhibits the Na-K-2Cl symporter in the loop of Henle. It exerts direct vasoactive effects, as well as hormonally mediated changes via release of renin, angiotensin II, and prostaglandins. These result in arterial vasoconstriction and venous vasodilation, as well as diuresis. [More…]
Furosemide is a loop diuretic. Furosemide’s mechanism of action is through inhibition of the Na-K-Cl cotransporter in the ascending loop of Henle by binding to this chloride transport channel and inhibiting the reabsorption of sodium, chloride, and potassium. [More…]
Foot and toe surgery can be successfully performed with an ankle block. There are five peripheral nerves that innervate the foot: Tibial, Deep peroneal, superficial peroneal, sural, and saphenous. [More…]
To best understand the physiology of the Fontan single ventricle, an understanding of the anatomy is essential. Staged procedures (i.e. B-T shunt, Glenn) are performed prior to ultimately reaching Fontan physiology, with the end result illustrated below (note that some variations exist). [More…]
The Fontan operation is the final stage palliation surgery for single ventricle disease states. The Fontan circulation dissociates the single systemic ventricle and blood from the pulmonary blood flow. [More…]
Avoiding secondary injury is of paramount importance in managing traumatic brain injury (TBI). Cerebral ischemia and hypoxia should be avoided. Hypotension and oxygen desaturation should be treated. [More…]
The endothelial glycocalyx is a 1µm thick continuous network of proteoglycans and glycoproteins on the intravascular aspect of endothelial cells that covers fenestrations and intercellular clefts. [More…]
Perioperative fluid replacement for children and infants is a complex and somewhat controversial topic. Traditionally, the first step in determining the hourly fluid requirements for a child described by Holliday and Segar and coined as the “4/2/1” rule: For children < 10 kg their hourly fluid needs are body weight (kg) x 4. For children […]
Flow through a tube can be described by the modified Bernoulli Equation, which states: Po = P + 1/2 ρ*U^2 [More…]
Common Hypothyroidism Polymyalgia rheumatica Autoimmune disorders (Rheumatoid arthritis, SLE) [More…]
Oxygen travels in the blood as a soluble gas or bound to hemoglobin. A significantly larger portion of oxygen is bound to hemoglobin and a relatively smaller portion is dissolved in blood. [More…]
Fetal heart rate monitoring is done either externally by a Doppler ultrasound monitor attached to the mother’s abdomen, or internally by elecrocardiography monitor attached to the fetus’ presenting part. Internal, or direct monitoring, requires rupture of membranes and cervical dilation of at least 1.5 cm. [More…]
Fenoldopam is a selective DA1-receptor agonist that has many of the benefits of DA but with little or no alpha or beta adrenoceptor or DA2-receptor agonist activity. [More…]
Relevant Anatomy Femoral nerve (posterior divisions of L2-4) is formed in the psoas major muscle, runs between psoas and iliacus muscles and enters the thigh under the inguinal ligament lateral to the femoral artery, at which point it divides into multiple terminal branches (usually classified as anterior [mostly cutaneous] and posterior [mostly motor]). [More…]
Indications include hip, femur, patella, quadriceps tendon, and knee surgery. Femoral nerve is the largest branch of the lumbar plexus (L2-L4). [More…]
Occur in 0.5% of RBC transfusions and 30% of platelet transfusions . Febrile reaction may occur without hemolysis. [More…]
Incidence/Mortality Estimated to occur in 3-10% of orthopedic trauma patients. Mortality is 10-20% [More…]
Turbulent gas flow increases with increasing gas density and gas flow rate. Decreasing gas density with heliox (molecular weight 9.6) instead of air (molecular weight 29) to ventilate patients helps to relieve airway obstruction e.g. in tracheal stenosis. [More…]
When an electrical current is applied to the myocardium, electrons present at the outer surface of the myocytes stimulate voltage-dependent sodium channels present within the cell membranes causing rapid cellular depolarization. [More…]
Recordings for SSEPs (somatosensory evoked potentials) are generated at a peripheral nerve, and recorded at the cortical or subcortical level. The signal travels via a peripheral nerve to the appropriate dorsal root ganglion, into the posterior spinal column, the medial lemniscus to the thalamus, and then to the sensory cortex. [More…]
Normal mixed venous oxygen tension (PvO2) is approximately 40 mmHg, representing the balance between oxygen consumption and oxygen delivery. [More…]
The depth of anesthesia is dependent on the anesthetic agent’s partial pressure (or tension) in the brain. [More…]
Massive Blood Loss/Transfusion 30% of factor VIII are needed for adequate hemostasis during surgery. [More…]
Facet joint arthropathy presents as localized lumbosacral back pain, without radicular neuropathic symptoms. [More…]
Functional Residual Capacity. The amount of volume remaining in the lung after a normal exhalation. [More…]
The lung volume at the end of a normal exhalation is called functional residual capacity (FRC). At this volume, the inward elastic recoil of the lung approximates the outward elastic recoil of the chest (including resting diaphragmatic tone). [More…]
Variable decelerations are the most common type of decelerations and are transient decreases in fetal heart rate that characteristically vary in duration, shape/magnitude, and timing/onset. [More…]
90% of the citrate found in whole blood products is found in FFP and platelets (not PRBCs). Citrate chelates calcium (and magensium) (that is why it is used, to prevent clotting of store blood products) and this is the mechanism of citrate intoxication. [More…]
Replacement of Isolated Factor Deficiencies FFP is efficacious for treatment of deficiencies of factors II, V, VII, IX, X, and XI when specific component therapy is neither available nor appropriate. [More…]
The fractional excretion of sodium, or FENA, is a calculated value used in the assessment of acute renal failure. It is an assessment of how much sodium is being excreted in the urine in comparison to how much total sodium the kidneys are “seeing” in the plasma. [More…]
The neuromuscular junction (NMJ) is a synapse between a presynaptic motor neuron terminal and a postsynaptic skeletal muscle fiber. [More…]
Common problems associated with prematurity include respiratory distress syndrome, apnea, hypoglycemia, hypocalcemia, hypomagnesemia, hyperbilirubinemia. [More…]
The purpose of intraoperative evoked potentials is to monitor neural pathways in hopes of avoiding iatrogenic injury to the nervous system. Sensory evoked potentials (SEPs) evaluate the integrity of ascending sensory tracts while motor evoked potentials (MEPs) deal with the functionality of descending motor pathways. [More…]
April 2022: Dr. Vanessa Olbrecht and OpenAnesthesia Editor Dr. Aditee Ambardekar discuss virtual reality and pain management.
There are multiple modalities currently used in practice to prevent paraplegia after aortic surgery including distal aortic perfusion, lumbar drains to monitor ICP and drain CSF, reimplantation of intercostal arteries, and moderate hypothermia. [More…]
Unconsciousness after intravenous etomidate results from binding to the GABA receptor and increasing its affinity for GABA. [More…]
Nonbarbiturate hypnotic, no analgesic activity, used for induction & sup of anesthesia. Decreases cerebral metabolism, cerebral blood flow, and intracranial pressure. (superior to propofol in maintaining cerebral perfusion pressure) More…
Drugs that decrease Lower Esophageal Sphincter (LES) tone Nitroglycerins (Isosorbide dinitrate, glycerylnitrate, itramintosylate, trolnitrate) Nitroprusside [More…]
Vasoconstrictors, such as epinephrine, can be added to local anesthetics. The addition of epinephrine causes multiple effects. [
Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. [More…]
Acute epiglottitis (supraglottitis) in the pediatric population is a potentially life threatening bacterial infection involving the supraglottic structures (lingular surface epiglottis, arytenoids, aryepiglottic folds). [More…]
Vasoconstrictors, such as epinephrine, can be added to local anesthetics. The addition of epinephrine causes multiple effects.[More…]
Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. [More…]
Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. [More…]
Some argue against doing a “test dose” because it lacks specificity and sensitivity for picking up an IT/IV epidural catheter placement. [More…]
Patient positioning during initiation of epidural blockade does not appear to affect the resultant spread of analgesia or anesthesia. [More…]
Postoperative ileus is almost universal following major abdominal surgery. Nearly 100 years ago, Cannon and Murphy demonstrated that opening the peritoneal cavity and manipulating the intestines resulted in significant inhibition of GI tract contractile function in dogs. [More…]
Postoperative ileus is almost universal following major abdominal surgery. Nearly 100 years ago, Cannon and Murphy demonstrated that opening the peritoneal cavity and manipulating the intestines resulted in significant inhibition of GI tract contractile function in dogs. [More…]
Clonidine functions as a sympatholytic by stimulating presynaptic α2-receptors leading to decreased release of norepinephrine at both central and peripheral adrenergic terminals. More…
Dyspnea may occur due to proprioceptive blockade of afferent fibers from abdominal and chest wall muscles. Need to assess adequacy of ventilation then reassure the patient. More…
Iliac crest is at L3-4, inferior scapula at T7. Structures superficial to deep: skin, fat, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura mater. More…
Complications of epidural analgesia can be broken down into three main categories: complications related to drug toxicity, complications related to needle/catheter placement, and exaggerated effects of appropriately injected drug. More…
North American guidelines have recommended early enteral nutrition WITHOUT parenteral nutrition for caloric deficiency in the first seven days of critical illness. More…
Enoxaparin, like any LMWH, is derived by depolymerization of unfractionated heparin and retains UFH’s ability to activate antithrombin and thereby provide anticoagulation. More…
Originally introduced for colorectal surgery and subsequently expanded to include other surgical specialties, Enhanced Recovery After Surgery (ERAS) protocols aim to reduce hospital length of stay, cost, and complication rates while increasing patient comfort and satisfaction. More
● Decreased pulmonary compliance. Increased peak inspiratory pressure and plateau pressure [More…]
Indications Endobronchial intubation to achieve one lung ventilation has absolute and relative indications. [More…]
The safe transfusion of blood and blood products is dependent upon antigen compatibility. Antigens on red blood cells are carbohydrate-based molecules that are recognized by antibodies. [More…]
Anesthetic options for an emergency cesarean include spinal, epidural, conversion of a labor epidural, a combined spinal-epidural (CSE), general anesthesia and local anesthesia. [More…]
Emergence delirium (ED) —a state of confusion, agitation, and restlessness—is seen with arousal from volatile agents at the completion of delivery of an anesthetic, and is a potentially dangerous phenomenon which has been associated with loss of central or peripheral access, self-extubation, and both patient and provider injury. [More…]
According to Miller’s Anesthesia, approximately 10% of adult patients over the age of 50 will experience some degree of post-op delirium 1-5 days of after surgery. [More…]
March 2022: Dr. Genevieve Staudt and OpenAnesthesia Editor Dr. Jina Sinskey discuss Fontan physiology.
Factor treatment: 1. Prothrombin complex concentrate Prothrombin Complex Concentrate (PCC) (trade name Octaplex or Ocplex[1]) is a combination of blood clotting factors II, VII, IX and X, as well as protein C and S. [More…]
Intracranial pressure (ICP) is determined by the volume of brain parenchyma (80%), blood (12%), and CSF (8%) within a rigid cranial vault. [More…]
FRC = residual volume + expiratory reserve volume = volume of gas in the lungs after normal expiration [More…]
Sodium levels are affected by ADH (hypothalamus), aldosterone (renin-angiotensin-aldosterone axis), glucocorticoids and mineralocorticoids (pituitary axis). [More…]
Vasopressin, also known as antidiuretic hormone (ADH), is a peptide hormone made in the hypothalamus and has both an immediate and long term effect on hemodynamics. [More…]
Rare autoimmune disorder, causes peripheral muscle weakness. Antibodies are directed against calcium channels at the neuromuscular junction. [More…]
The ex utero intrapartum treatment (EXIT procedure) involves partial delivery of the infant and maintenance of uteroplacental circulation long enough to secure the airway and provide potentially lifesaving interventions (bronchoscopy, tracheostomy, cannulation for ECMO) based on the condition of the neonate. [More…]
Many drugs use the kidney as a final means of elimination, and the neuromuscular blockers commonly used today are no exception. [More…]
Goal Directed Fluid Therapy (GDT) is a tenant of ERAS protocols, utilizing an intra-arterial waveform for automated measurements of pulse pressure variations (PPV) or stroke volume variation (SVV) in order to determine response to fluid boluses. [More…]
EMLA (Eutectic Mixture of Local Anesthetics) is a eutectic mixture of lidocaine 2.5% and prilocaine 2.5% formulated as an oil in water emulsion developed to anesthetize intact skin. [More…]
Opioids produce a dose related decrease in the frequency and amplitude of the EEG. [More…]
The stimulus leads to increases in cerebral blood flow and increased ICP. Initially, the seizure activity causes a large parasympathetic discharge with bradycardia, atrial or ventricular premature beats, and occasional asystole. [More…]
The stimulus leads to increases in cerebral blood flow and increased ICP. Initially, the seizure activity causes a large parasympathetic discharge with bradycardia, atrial or ventricular premature beats, and occasional asystole. [More…]
ECT requires both general anesthesia and paralysis. Pretreatment with glycopyrrolate may reduce the incidence of bradycardia and decrease oral secretions following the initial parasympathetic response. Induction is intravenous, followed by complete paralysis and placement of a bite block. [More…]
ECT requires both general anesthesia and paralysis. Pretreatment with glycopyrrolate may reduce the incidence of bradycardia and decrease oral secretions following the initial parasympathetic response. Induction is intravenous, followed by complete paralysis and placement of a bite block. [More…]
Electroconvulsive therapy (ECT) is an effective therapy for psychiatric disorders such as depression, mania, and affective disorders that have been refractory to standard medical therapy. [More…]
Before discussing contraindications, it is important to first understand the physiologic effects of ECT. These include : Large increases in cerebral blood flow and intracranial pressure [More…]
Cardiac Effects Following ECT stimulus 1. Initial tonic phase is characterized by profound stimulation of the parasympathetic nervous system which can result in 2. Sinus bradycardia [More…]
When considering drug selection for ECT, several things should be carefully considered. 1. Induction of GA that allows for quick emergence after the seizure 2. Use of medications that will not adversely affect the patients seizure (i.e. shorten duration) [More…]
External cardiac pacemaker function should not be affected by ECT because the current path is far from the heart. Patients with a history of CAD, CHF, and valvular heart disease may benefit from invasive monitoring to assess myocardial function and permit aggressive hemodynamic control. [More…]
Myxedema coma typically presents as decreased mental status and hypothermia in a patient with either chronic, severe hypothyroidism or any form of hypothyroidism in the setting of a significant physiological stressor (infection, MI, sedative medications/opioids). [More…]
February 2022: Dr. Patrick Fernandez and OpenAnesthesia Editor Dr. Debnath Chatterjee discuss the anesthetic care of children with food and PCN allergies
Definition: full-thickness separation of the uterine wall and the overlying serosa [More…]
In an adult the dural sac terminates caudally at S2 . The termination of the adult spinal cord, on the other hand, is at L1-2 and is called the conus medullaris.
The dura mater is the outermost of the spinal meninges. It is a thick, fibroelastic membrane composed of collagen and elastin fibers that is a continuation of the cranial dura. [More…]
Duchenne’s Muscular Dystrophy (DMD) is an x-linked recessive disease involving a mutation of the protein dystrophin. Dystrophin is found in skeletal, cardiac, and smooth muscle as well is in the brain, therefore manifestations follow suit. [More…]
Controlled hypotension is the process of deliberately reducing a patient’s blood pressure (typically, ~30% reduction of baseline MAP) for a therapeutic purpose. This is accomplished by reduction of either SVR or CO. [More…]
– Process of primary respiratory impairment resulting from submersion/immersion in a liquid medium – Spectrum of presentation based on severity [More…]
The immediate physiologic response to drowning is breath-holding. After breath-holding, involuntary laryngospasm can occur with entry of fluid into the oropharynx and larynx. [More…]
Respiratory distress is the most frequent cause of neonatal ICU admission in the US.1 One reason neonates poorly tolerate increased work of breathing is the immature development of their ventilatory musculature. [More…]
The glycocalyx is a complex layer between the endothelium and flowing blood. It is composed mostly of glycoproteins and proteoglycans. [More…]
Magnesium plays an essential role in a number of cellular functions, but primarily serves as a physiologic antagonist of calcium. [More…]
Residual neuromuscular blockade (NMB) can result in patient discomfort and distress as well as inadequate respiration and may precipitate respiratory distress/failure, necessitating reintubation. [More…]
The mechanism of action for volatile anesthetics that produce immobility and amnesia is not entirely understood. Current evidence supports the idea that response to noxious stimuli is ablated by inhaled anesthetics at the level of the spinal cord, while the amnestic effects are mediated within the brain. [More…]
Hemophilia occurs with an incidence of about 1/10,000 and follows an X-linked recessive inheritance pattern. Thus, it almost always affects males. There are two major subtypes of this disease: Hemophilia A and Hemophilia B. [More…]
The Left Ventricle (LV) is a conical shaped chamber that can easily be visualized with TEE. The apex is the point of the cone and the base represents the LV inflow tract via the mitral valve and the LVOT via the Aortic Valve. [More…]
Doxorubicin is a chemotherapy drug that is administered intravenously. It is used in treatment of leukemia, lymphoma, breast cancer, soft tissue sarcoma, multiple myeloma, and other cancers. [More…]
Cardiotoxicity is the main one that everyone expects you to know but the list is long. [More…]
Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. They may also have obstructive sleep apnea and lax cervical ligaments as well as other cervical abnormalities (ex. odontoid) leading to cervical instability (atlantooccipital instability in 9%). [More…]
Most common is the Robertshaw tube, available as both a L and R-sided tube. Sizes include a 28F (pediatric) as well as 35F, 37F, 39F, and 41F. All are PVC with D-shaped lumens, disposable. Blue represents the endobronchial lumen/cuff. Note that R-sided tubes have a donut-shaped endobronchial cuff, which allows separate access to the RUL. […]
The Doppler shift occurs when a source of wave is moving toward or away from a receiver (or when the receiver is moving toward or away from a wave source). When the distance between a wave source and the receiver is getting smaller, the observed frequency of the wave is greater than the source frequency. […]
The liver is responsible for synthesis of clotting factors and other important proteins involved with regulating the coagulation cascade. Therefore, even in patients with a normal preoperative coagulation profile, alterations in bleeding and thrombosis have been observed following donor hepatectomy. [More…]
Pharmacologically, donepezil (Aricept®) is an acetylcholinesterase inhibitor. It is most active in the central nervous system, where it is used to increase levels of acetylcholine in patients with Alzheimer’s type dementia. [More…]
Loop Diuretics inhibit the Na+ K+ 2Cl- transporter in the thick ascending limb of the Loop of Henle. Due to their mechanism of action they may result in hypokalemia. [More…]
Sulfonamide derivatives Carbonic anhydrase inhibitors, such as acetazolamide, work at the proximal convoluted tubules to block the cleavage and subsequent resorption of bicarbonate to water and carbon dioxide. [More…]
An adverse event is an undesirable outcome that results from an aspect of that patient’s clinical care and not from the underlying disease process. Over the past several decades, the medical community has increasingly embraced literature demonstrating the benefits to both providers and patients of disclosing adverse events. [More…]
Diabetic autonomic neuropathy can be defined as dysfunction of the sympathetic and parasympathetic nervous systems due to poor glycemic control. [More…]
Local anesthetic toxicity (LAST) is a relatively rare complication that results from elevated plasma concentrations of local anesthetics most often after accidental intravascular injection. [More…]
Multiple changes are seen in the coagulation system during pregnancy. The greatest change occurs at term. Overall, pregnancy is a hypercoagulable state. However, the traditional measures of coagulation (PT, aPTT, INR) either do not change or decrease slightly during pregnancy. [More…]
Aortic insufficiency (AI) is classifiable as acute or chronic. While there is no universally accepted definition for timeline, there are generalizable differences. Acute aortic insufficiency is very poorly tolerated; whereas chronic AI allows for the heart to accommodate. [More…]
As patients get older, multiple physiologic changes contribute to alterations in pharmacokinetics (i.e., “what the body does to the drug”) and pharmacodynamics (i.e., “what the drug does to the body”); thus, differences in drug dosing are required to achieve the desired pharmacologic effect. [More…]
Minimally invasive direct coronary artery bypass (MIDCAB) originally describes left internal mammary artery (LIMA) takedown and anastomosis to the left anterior descending artery (LAD) via anterior thoracotomy, as performed either off-pump on on-pump with femoral cardiopulmonary bypass (CPB) cannulation. [More…]
Residual neuromuscular blockade (NMB) can result in patient discomfort and distress as well as inadequate respiration and may precipitate respiratory distress/failure, necessitating reintubation. [More…]
Jet ventilation allows for the delivery of oxygen through a high flow device via subglottic jet ventilation tube or 14-16 gauge catheter in cricothyroid membrane. Jet ventilation delivers high flows and small tidal volumes with passive exhalation. [More…]
The mechanism of action for volatile anesthetics that produce immobility and amnesia is not entirely understood. Current evidence supports the idea that response to noxious stimuli is ablated by inhaled anesthetics at the level of the spinal cord, while the amnestic effects are mediated within the brain. [More…]
Wall motion is assessed in the LV. Ischemia is the most common cause of wall motion abnormalities (WMA). In the setting of ischemia, contractility is downregulated or can be completely ceased. [More…]
Parasympathetic fibers originating in the dorsal vagal nucleus and nucleus ambiguus of the medulla synapse on cardiac tissue via the vagus nerve (Cranial nerve X). Branches of the right vagus largely innervate the SA node and left vagus largely innervates the AV node. [More…]
Nondepolarizing neuromuscular blocking drugs (NDNMBD) in recent use include mivacurium, atracurium, cisatracurium, vecuronium, rocuronium and pancuronium. These muscle relaxants bind ACh receptors in the neuromuscular junction but are incapable of inducing ion channel opening, functioning as competitive antagonists. [More…]
The corneal reflex plays an important role in the evaluation of a comatose patient particularly in the neurocritical care setting. This brainstem reflex is used for determination of neurological prognosis in cardiac arrest survivors and for the determination of brain death in those with irreversible, catastrophic brain death. [More…]
The serotonin syndrome is suspected when a patient is exposed to exogenous serotonergic medications, particularly if exposed to multiple agents. The symptoms include but are not limited to agitation, altered mental status, clonus, diaphoresis, tachycardia, hyperthermia and hypertension. [More…]
Tramadol is a synthetic centrally acting opioid receptor agonist with weak mu receptor affinity and even weaker kappa and delta affinity. Tramadol and its active metabolite (O-desmethyltramadol) binds to μ-opioid receptors in the central nervous system causing inhibition of ascending pain pathways and altering the perception of and response to pain. [More…]
Panhypopituitarism may be suspected, and diagnostic testing pursued as a result, when either a suspicious lesion or symptom presents in a patient. For example, if a patient is found to have a sellar mass, pituitary testing may be initiated even if the patient is otherwise asymptomatic given the known potential effect such lesions can have […]
Consciousness can be most simply described as an awake state of awareness although the specific definition and concept has been debated for ages by scientists and philosophers alike. [More…]
The original term “fulminant hepatic failure,” defined as “a severe liver injury, potentially reversible in nature and with onset of hepatic encephalopathy within 8 weeks of the first symptoms in the absence of pre-existing liver disease,” remains applicable today(1). [More…]
Anesthesiologists are exposed to radiation intraoperatively through the increasing use of x-rays, fluoroscopy, and computed tomography (CT) scanning. Exposure depends on the amount of time exposed for, total radiation intensity and the distance from radiation source. [More…]
Lasers are becoming increasingly common in the OR for a variety of procedures including laser lithotripsy and a variety of head and neck surgeries. When a laser is being used for a head and neck procedure, particularly in the airway, the case should be considered high risk for airway fire. [More…]
Laryngospasm is a relatively common complication of general anesthesia, occurring at much higher frequency in children as compared to adults. Up to 2% of children younger than 1 year may suffer laryngospasm during general anesthesia. [More…]
The oculocardiac reflex (OCR), also known as Aschner reflex or Trigemino-Vagal reflex, is defined by a decrease in HR by >20% following globe pressure or traction of EOMs. [More…]
Herpes zoster is caused by the varicella zoster virus which lies dormant in dorsal root ganglia and becomes active again during immunosuppression or as immunity declines with advancing age. [More…]
Opioid tolerance is a phenomenon that occurs when administering a fixed dose of an opioid results in decreasing analgesia, requiring higher doses to achieve the same effect over time. This manifestation is thought to involve the N-methyl-D-aspartate (NMDA) receptor, though the mechanism is not fully understood. More…
When a blood transfusion is implicated in the development of ARDS, it is referred to as Transfusion-Related Acute Lung Injury (TRALI). Distinct from Transfusion Associated Circulatory Overload (TACO), TRALI occurs without evidence of excessive intravascular volume or cardiac compromise. More…
Upper extremity cutaneous innervation is supplied primarily by the Brachial Plexus, emerging from spinal roots C5-T1 – the exceptions being the supraclavicular nerve (C3/4) and the Intercostobrachial nerve (branches from intercostal nerves). More…
Obstructive sleep apnea (OSA) is characterized by recurrent episodes of upper airway collapse during sleep that severely limit airflow despite breathing efforts. It has been associated with adverse long-term health outcomes as well as increased perioperative complication risk. More…
The spinal cord terminates with the conus medullaris located at L3 until 1 year of age. This is in comparison to L1 in adults. More…
Line isolation systems (isolation transformer + line isolation monitor) protect from electrocution by turning a normal “grounded system” (exists outside the operating room) which only needs a single fault to cause electrocution into a “protected” system in which two faults are needed to deliver a shock. More…
Ninety percent of myocardial oxygen demand is determined by myocardial contractile activity. In circumstances when the myocardium of the left ventricle must generate additional force to eject blood into the systemic circulation more oxygen will be required. More…
– Process of primary respiratory impairment resulting from submersion/immersion in a liquid medium – Spectrum of presentation based on severity : Asymptomatic – no cough, or dyspnea, normal vital signs, no pulmonary findings More…
Patient positioning during initiation of epidural blockade does not appear to affect the resultant spread of analgesia or anesthesia. The patient may be placed in either the lateral or sitting position. More…
Transfusion-associated Graft-Versus-Host-Disease (Ta-GVHD) is a rare phenomenon that is distinct from the more common form of GVHD that occurs following stem cell transplant. More…
Respiratory complications are the most common cause of mortality following a spinal cord injury. The extent of respiratory compromise is highly dependent on the level of the injury. More…
Opioids are probably the second most common class of medication used for neuraxial analgesia. Like all drugs, their pharmacokinetics are governed by their specific pharmacologic properties. One of these properties, the degree of lipid solubility, will be quickly reviewed. More…
Minute ventilation is determined by tidal volume multiplied by respiratory rate. In pressure control ventilation (PCV), inspiratory pressure and inspiratory time (Ti) (or respiratory rate and I:E ratio) are set, and tidal volume and inspiratory flow will vary. More…
Physiologic respiratory changes during pregnancy: By term, oxygen consumption and minute ventilation increase by about 50%. As the uterus enlarges, the diaphragm is pushed cephalad. This elevation is compensated by an increase in the anteroposterior diameter of the chest. Thoracic breathing is favored over abdominal breathing. Diaphragmatic motion is NOT restricted. More…
Hypertensive disorders are one of the leading causes of maternal mortality worldwide. Blood pressure typically falls early in pregnancy and reaches nadir between 16-20 weeks gestational age. Later in pregnancy, the blood pressure will return to baseline. More…
Hypoventilation (decreased chest wall movement, decreased FRC) along with ineffective cough due to pain and guarding leads to atelectasis and higher risk for pneumonia. More…
Perioperative antibiotics aimed at preventing surgical site infection should be administered intravenously within 60 minutes before incision; studies have shown that this is the interval in which the risk of surgical site infection is lowest. More…
Initial resuscitation goals during first 6 hours include: CVP 8-12mmHg (or 12-15mmHg on the vent) More…
Infants have a lower percentage of fatigue-resistance Type I muscle fibers relative to adults. Skeletal muscle fibers are classified as type I or type II. [More…]
- The glycocalyx modulates blood viscosity and hematocrit in the microcirculation. It repels red blood cells from the endothelium and shields it from leukocyte and platelet interactions.
- More…
The Glasgow coma scale is an assessment tool utilized to measure level of consciousness after brain injury. GCS
December 2021: Dr. Proshad Efune and OpenAnesthesia Editor Dr. Aditee Ambardekar discuss the dual training pathway in pediatric critical care and pediatric anesthesiology.
To simplify, a one-way ANalysis Of VAriance (ANOVA) is like a t-test, but for three or more groups. Note that t-tests and ANOVAs are applied to continuous variables (i.e., comparing sample means for variables such as age, BMI, operative time, MAP, SpO2, EBL, morphine equivalents, duty hours, ITE scores). [More…]
The RCRI (Revised Cardiac Risk Index) is used to assess the risk of MACE (Major Adverse Cardiac Events) during surgery, and includes 6 criteria to estimate this risk. These criteria are the presence or history of: Ischemic heart disease More…
The most common indication for ICD removal or lead extraction is system infection. Other indications include lead malfunction (fracture or failure), lead or device erosion, lead upgrade, retained lead or lead fragment causing potentially life-threatening arrhythmias, or thromboembolic complications or venous obstruction. [More…]
Indications: patients with hemodynamic instability or severe LV systolic dysfunction. Contraindications: Severe peripheral vascular disease (PVD) of the aortoiliac and femoral arteries – due to increased risk of lower extremity ischemia. [More…]
Adapted from Miller, Table 59-19, treatment for gradual desaturation during one lung ventilation: Increase FiO2 to 100% PEEP to ventilated lung [More…]
Causes of Hypoxia Inadequate Oxygen Delivery: inadequate minute ventilation or FiO2; mechanical failure, disconnect R-L Shunt: intracardiac shunting [More…]
Hypoxemia is defined as a low level of oxygen in the blood. This is not to be confused with hypoxia, which is a condition where the oxygen delivered to an organ or the entire body is insufficient. [More…]
Hypotension is a late finding in pediatric patients (children may maintain a normal blood pressure until 35% of blood volume is lost). [More…]
Speed of recovery from inhalational GA is directly proportionate to alveolar ventilation but inversely proportionate to the solubility of the agent. [More…]
Redistribution of heat to the peripheral tissues via vasodilation is responsible for the first 0.5-1.5o C drop in core body temperature. [More…]
Hypothermia during general anesthesia is the most common preoperative thermal disturbance. It can be caused by a variety of factors. Besides a cold operating room, impaired thermoregulation tends to be the biggest cause. [More…]
In humans, heat (or “thermal energy”) is more concentrated in the core than it is in the extremities. This is why your hands or feet may be cold even though you core is normothermic. Thus, the core temperature may be 37 but the mean body temperature might be 36 or 35.5. [More…]
Phosphate is very important as a source of chemical energy as it forms ATP in all cells. When phosphate is low, muscles do not function well, in particular the respiratory muscles (including the diaphragm). [More…]
Chronic hypophosphatemia is associated with short stature, rickets phenotype (bowing of the legs), and bone pain. [More…]
Hypokalemic periodic paralysis is a disorder characterized by episodes of weakness, sparing the respiratory muscles, with a matching fall in serum potassium that lasts anywhere from a few hours to a few days. [More…]
Hypokalemia is an electrolyte imbalance that may be present in elderly patients with salt-wasting alkalosis or in patients who chronically use diuretics. [More…]
Background : Glucagon was originally thought to be a “contaminant” that caused hyperglycemia found in pancreatic extracts in studies from 1923. [More…]
Hypocarbia exists when PaCO2 is below 35 mmHg, which is typically the result of hyperventilation causing a respiratory alkalosis. [More…]
Hypocalcemia typically prolongs the Q-T interval on electrocardiograms and may lead to complete heart block. [More…]
Hyperthyroidism results from excess synthesis and release of thyroid hormone SYMPTOMS Nervousness [More…]
Hyperthyroidism is defined as a hypermetabolic state that is characterized by elevated peripheral thyroid hormones. [More…]
Chronic Hypertension : Hypertension diagnosed prior to conception due to systolic values greater than 140 mmHg and/or diastolic values greater than 90 mmHg OR hypertension that does not resolve in the postpartum period. [More…]
Epidemiology: Primary hyperparathyroidism occurs in about 0.1% of the population, most commonly begins in the third to fifth decades of life, and occurs two to three times more frequently in women than men. [More…]
Increases in plasma magnesium are often due to excessive intake (magnesium-containing antacids or laxatives) and/or renal impairment. Iatrogenic hypermagnesemia can also occur during magnesium sulfate therapy for gestational hypertension in the mother as well as the fetus. [More…]
Hyperkalemic periodic paralysis is an autosomal dominant disease leading to intermittent weakness associated with hyperkalemia and often precipitated by a potassium-rich meal, rest after exercise, or stressful situations. The paralysis lasts up to an hour. [More…]
Shift K+ from plasma back into the cell: intravenous glucose (25 to 50 g dextrose, or 1-2 amps D50) plus 5-10 U regular insulin will reduce serum potassium levels within 10 to 20 minutes, and the effects last 4 to 6 hours, hyperventilation , β-agonists. [More…]
Normal p50 is 27 mm Hg . Several factors can cause a right shift (increased unloading) in the oxyhemoglobin dissociation curve – acidemia , hypercarbia , increased temperature , and increased 2,3-DPG (all of which are more effective during hypoxemia, ex. at tissue levels). [More…]
Hyperchloremic metabolic acidosis is defined as metabolic dysfunction characterized by acidemia (pH < 7.35), a normal anion gap, and an elevated serum chloride. In anesthesia practice, it is often the result of fluid resuscitation with normal saline (NS). [More…]
Hypercapnia, or high PaCO2, can occur in numerous scenarios during anesthetic and post-anesthetic care. In the operating room, hypercapnia is typically detected with capnography; however, this monitor is not always available outside of the operative environment. [More…]
Symptoms: mild to moderate hypercalcemia (11 to 14 mg/100 mL) often has no symptoms, but when levels > 15 mg/100 mL, clinical changes become more common. [More…]
General Principles of airway management in COVID+ patients Departmental Links for General Information Massachusetts General Hospital Columbia Mt. Sinai Johns Hopkins Downloadable Educational Materials COVID19 Labor to Cesarean Delivery: Case Flow and Facilitator’s Guide COVID19 L&D Drills Evaluation Form Obstetric Anesthesia and COVID19: Simulation Exercises Name/Claim/Aim: A new crisis resource management paradigm by the Center […]
November 2021: Dr. Bishr Haydar and OpenAnesthesia Editor Dr. Jina Sinskey discuss pediatric anesthesia transport.
Hyperbaric oxygen (HBO) is when oxygen is delivered in an environment where the barometric pressure is more than 1 atmosphere. This is common therapy for arterial air embolism, decompression sickness, severe profound anemia or hypoperfusion, severe CO poisoning, and gas gangrene from C. perfringens. [More…]
Hyperbaric oxygen indication is listed below: Decompression sickness Air or gas embolism Carbon monoxide poisoning; cyanide poisoning; smoke inhalation [More…]
Hyperbaric oxygen therapy (HBO) is an adjunctive therapy used to treat a number of specific conditions, including acute venous or arterial gas embolism (to reduce the gas bubble size), severe carbon monoxide or cyanide poisoning, to improve wound healing (non-healing ulcers, skin grafts, etc), decompression sickness, and acute traumatic or ischemic injuries (crush, compartment syndrome, […]
Specifically, thiazides inhibit sodium reabsorption at the distal convoluted tubule, promoting naturesis and water loss. Like loop diuretics (which block reabsorption in the ascending tubule) potassium excretion is increased. [More…]
Epinephrine (adrenal medulla) and norepinephrine (nerve endings) are released by the sympathetic nerve system and result in gluconeogenesis , glycogenolysis , lipolysis , and glucagon release (in addition to their hemodynamic effects). [More…]
The choice between regional (spinal or epidural) and general anesthesia has been evaluated extensively for hip fracture surgery. [More…]
Incidence/Mortality Pathophysiology Theory #1 (mechanical): large fat droplets are released into the venous system. [More…]
Respiratory quotient is the ratio of VCO2 and VO2: RQ = CO2 eliminated/O2 consumed Under typical metabolic conditions with stable respiratory function, the range of RQ in human metabolism is approximately 0.7 to 1.0. A value of 1.0 is consistent with pure carbohydrate oxidation, whereas a value of 0.7 is consistent with pure fat oxidation. […]
Hydroxyethyl starch (hetastarch) is a colloid solution available in the United States as a 6% solution in 0.9% NaCl (Hespan ), as well as Hextend . The larger molecules (the range is from 10,000 to 2 million daltons) of Hespan are degraded by amylase. [More…]
Maternal primary infection with HSV before pregnancy does not usually impact the intrauterine development of the fetus. Increased rates of miscarriage and IUGR following primary HSV infection during pregnancy have been reported. [More…]
Garlic lowers blood pressure, lipid levels, and thrombus formation, in addition to inhibiting platelet aggregation through a variety of mechanisms (important components include alliin, allicin, and ajoene, the latter of which may potentiate other platelet inhibitors). [More…]
Garlic: inhibits platelet aggregation (organosulfur), discontinue for seven days *Ginkgo: inhibits platelet activating factor (terpenoids, flavonoids), discontinue for thirty six hours. [More…]
Garlic is used for its potential to prevent atherosclerosis by reducing blood pressure, thrombus formation, and serum lipid and cholesterol levels. The development of concentrated garlic preparations has made it possible for patients to take otherwise unachievable high doses, which may increase the risk of adverse effects. [More…]
Hepatopulmonary syndrome is a condition in patients with liver disease that is characterized by arterial hypoxemia caused by pulmonary vasodilatation. Patients with Hepatopulmonary syndrome have dyspnea, which can be severe, in addition to other signs of hypoxemia such as cyanosis and digital clubbing. [More…]
The best lab test for measuring hepatic synthetic function is PT/INR. PT, or prothrombin time, is a laboratory measure of the extrinsic and common clotting system. INR, or international normalized ratio, is a standardized value that measures the same system but eliminates variance found in lab PT measurements. [More…]
The average adult liver synthesizes approximately 15 g of albumin per day with a half-life of approximately 20 days, with 4 percent degraded daily. Thus if hepatic protein synthesis came to a halt, it would not be noticeable for several days. [More…]
The liver serves several metabolic functions within the body including protein synthesis and metabolism. The liver is responsible for an array of proteins. Endocrine proteins produced by the liver include angiotensinogen, thrombopoietin, and insulin-like growth factor I. [More…]
The liver is unique in that it has dual blood supply from both the portal vein and the hepatic artery; in total the liver receives 25% of cardiac output. The portal vein is derived from the confluence of the superior mesenteric vein, inferior mesenteric vein, and splenic vein. [More…]
The liver has a dual blood supply with 50% of its oxygen supply coming from the hepatic artery and the other 50% coming from the portal vein. One way the liver ensures proper oxygenated blood delivery is through an intrinsic response known as the hepatic arterial buffer response (HABR). [More…]
October 2021: Dr. Francis Veyckemans and OpenAnesthesia Editor Dr. Debnath Chatterjee discuss pediatric tracheal extubations.
The liver receives around 25% of cardiac output. The blood supply is from two sources – the portal vein contributes around 75% of blood supply and the hepatic artery around 25%. Given the higher content of oxygen in arterial blood supply, the overall distribution of oxygen supply between each source is around 50:50. [More…]
The blood supply to the liver is provided by the portal vein (75%) and hepatic artery (25%); each vessel provides about 50% of the oxygen requirements of the liver. [More…]
Heparin is a highly sulfated glycosaminoglycan which is widely used as an injectable anticoagulant. Heparin binds to antithrombin III causing a conformational change that results in its activation through an increase in the flexibility of its reactive site loop. [More…]
Hemophilia occurs with an incidence of about 1/10,000 and follows an X-linked recessive inheritance pattern. Thus, it almost always affects males. There are two major subtypes of this disease: Hemophilia A and Hemophilia B. [More…]
3000 mg of bilirubin is formed daily, 75% of which is from heme metabolism and 25% of which is from other proteins (ex. cytochrome P450). [More…]
Direct laryngoscopy and tracheal intubation in patients with normal protective airway reflexes results in stimulation of the sympathetic nervous system. This, in turn, may lead to hemodynamic changes such as increased HR, elevated systolic BP, and cardiac arrhythmias (especially ventricular bigeminy). [More…]
The process of HD involves a dialyzer which contains semipermeable membrane with microscopic holes that allow only some substances to cross. Dialysate, also called dialysis fluid, is a solution of pure water, electrolytes and salts, such as bicarbonate and sodium, passes through one side of the membrane while blood from patients circulate through the other […]
Acute effects: hypotension (too much fluid removed), “dialysis disequilibrium” (rapid fluid/urea shifts resulting in cerebral edema – headache, nausea, can progress to convulsions and coma) hypercalcemia, fever , arrhythmias (due to hypokalemia , especially in patients on digoxin,) bleeding (due to heparinization.) [More…]
Chemical Properties: • First and lightest noble gas. • It is non-toxic, colorless, odorless, and tasteless. [More…]
Gas flow through a tube is either laminar (parabolic velocity profile) or turbulent (flat velocity profile). The nature of flow is dependent on several physical properties of the gas (density, viscosity) as well as of the flow itself (velocity, length of tubing), all of which can be combined mathematically into the Reynold’s number, Re (Re […]
Note that in laminar flow, Heliox offers no advantages, as it has approximately the same viscosity as air. Also note that Heliox is ~ 70% helium, thus the potential benefit of improved gas flow must be balanced by the knowledge that a lower FiO2 may be delivered. [More…]
Hypothermia is often defined as a core body temperature of less than 36 degrees Celsius. In an normal individual not under anesthesia, the hypothalamus tightly regulates core body temperature through warming or cooling processes. [More…]
Hypothermia can be defined as core body temperature less than 360C. Maintaining normal core temperature is important for the function of enzyme systems. [More…]
The transplanted heart will not be able to respond to drugs that act by blocking the parasympathetic system because these connections were severed during the transplant. [More…]
Complete heart block is most commonly caused by myocardial infarction. An inferior wall MI (RCA in 85% of population) can damage the AV node, leading to complete heart block. [More…]
Why is head down BAD in cases of hypotension? When trendelenberg position is used with the hopes of raising a pt’s blood pressure, INITIALLY central blood volume increases by 1L in the adult patient and this will cause reflex barostimulation and then systemic vasodilation, which will then lead to decreased CO, SV and therefore DECREASED […]
The Haldane Effect describes the effect of oxygen on CO2 transport . The Haldane Effect (along with the Bohr Effect) facilitates the release of O2 at the tissues and the uptake of O2 at the lungs. [More…]
Hypoxic pulmonary vasoconstriction (HPV) is a physiologic mechanism by which lung perfusion is adjusted to match ventilation through the contraction of vascular smooth muscle in the pulmonary circulation in response to low regional partial pressure of oxygen. [More…]
In patients with HOCM, systolic septal bulging into the LVOT, malposition of the anterior papillary muscle, drag forces, and hyperdynamic LV contraction (causing a Venturi effect) may contribute to creation of a LVOT gradient. [More…]
After inoculation, patients will often experience a flu-like illness. Over the first 4-8 weeks, patients have significant viremia with a drop in CD4+ cell count with a drop in virema and an increase in CD4+ cell count by the end of the first 4-8 weeks. [More…]
The Health Insurance Portability and Accountability Act of 1996 (HIPAA) includes Standards for Privacy of Individually Identifiable Health Information (“Privacy Rule”). The Privacy Rule established a set of national standards for the protection of certain health information. [More…]
There are two known histamine receptors, designated H1 and H2. H1 receptor antagonists are typically utilized to suppress the body’s histamine-mediated effects in anaphylactoid or anaphylactic reactions. [More…]
In the landmark study published by Dr. Rivers (NEJM circa 2001), early goal-directed therapy was shown to reduce absolute mortality in patients with severe sepsis. The Surviving Sepsis Campaign built on Rivers foundation and published international guidelines in 2004 and the guidelines have been updated every 4 years since then. [More…]
Glycopyrrolate is a synthetic antimuscarinic medication with anticholinergic properties similar to atropine. Compared to atropine (which has a tertiary ammonium structure), glycopyrrolate has a quaternary ammonium structure and is completely ionized at physiologic pH. [More…]
The adrenal cortex produces several classes of hormones, each derived from a cholesterol precursor. Glucocorticoids are hormones that promote gluconeogenesis and assist in the metabolism of energy sources, as well as mitigate the inflammatory cascade and delay bone formation. [More…]
The GCS is the summation of scores for eye, verbal, and motor responses. The minimum score is a 3 which indicates deep coma or a brain-dead state. The maximum is 15 which indicates a fully awake patient (the original maximum was 14, but the score has since been modified). [More…]
Ventilatory responses to hypoxia, hypercapnia, and stress are reduced , while the depressant effects of both intravenous agents (benzodiazepines, opioids) and volatile anesthetics are more pronounced. [More…]
Flow through a tube can be described by the modified Bernoulli Equation, which states: Po = P + 1/2 ρ*U^2 [More…]
Oxygen travels in the blood as a soluble gas or bound to hemoglobin. A significantly larger portion of oxygen is bound to hemoglobin and a relatively smaller portion is dissolved in blood. [More…]
Fetal heart rate monitoring is done either externally by a Doppler ultrasound monitor attached to the mother’s abdomen, or internally by elecrocardiography monitor attached to the fetus’ presenting part. Internal, or direct monitoring, requires rupture of membranes and cervical dilation of at least 1.5 cm. [More…]
September 2021: Dr. Andrew Costandi and OpenAnesthesia Editor Dr. Aditee Ambardekar discuss anesthesia for pediatric transplant.
Fenoldopam is a selective DA1-receptor agonist that has many of the benefits of DA but with little or no alpha or beta adrenoceptor or DA2-receptor agonist activity. Fenoldopam has been shown to exert hypotensive effects characterized by a decrease in peripheral vascular resistance, along with an increase in renal blood flow, diuresis, and natriuresis. [More…]
Relevant Anatomy Femoral nerve (posterior divisions of L2-4) is formed in the psoas major muscle, runs between psoas and iliacus muscles and enters the thigh under the inguinal ligament lateral to the femoral artery, at which point it divides into multiple terminal branches (usually classified as anterior [mostly cutaneous] and posterior [mostly motor]). [More…]
Febrile reaction may occur without hemolysis. Recipient antibodies directed against HLA antigens on donor WBCs or platelets are the most common cause, although cytokines released from WBCs of stored products (particularly platelets) may also be a cause. [More…]
Occur in 0.5% of RBC transfusions and 30% of platelet transfusions . Febrile reaction may occur without hemolysis. Recipient antibodies directed against HLA antigens on donor WBCs or platelets are the most common cause, although cytokines released from WBCs of stored products (particularly platelets) may also be a cause. [More…]
Incidence/Mortality Pathophysiology Theory #1 (mechanical): large fat droplets are released into the venous system. [More…]
Turbulent gas flow increases with increasing gas density and gas flow rate. Decreasing gas density with heliox (molecular weight 9.6) instead of air (molecular weight 29) to ventilate patients helps to relieve airway obstruction e.g. in tracheal stenosis. [More…]
Recordings for SSEPs (somatosensory evoked potentials) are generated at a peripheral nerve, and recorded at the cortical or subcortical level. The signal travels via a peripheral nerve to the appropriate dorsal root ganglion, into the posterior spinal column, the medial lemniscus to the thalamus, and then to the sensory cortex. [More…]
Normal mixed venous oxygen tension (PvO2) is approximately 40 mmHg, representing the balance between oxygen consumption and oxygen delivery. A true PvO2 measurement must come from a mixed venous blood sample containing venous drainage from the SVC, IVC, and the heart. [More…]
The depth of anesthesia is dependent on the anesthetic agent’s partial pressure (or tension) in the brain. The goal in giving an inhalation anesthetic is to achieve an adequate partial pressure of anesthetic (Panes) in the brain to cause a desired level of CNS depression to achieve general anesthesia. [More…]
Also known as acquired Hemophillia A Treat bleeding and its complications If titer < 5 BU, try human FVIII infusions, aiming for plasma levels of 30– 50% [More…]
Massive Blood Loss/Transfusion 30% of factor VIII are needed for adequate hemostasis during surgery. [More…]
Most common hereditary hypercoagulable state: 4-8% population Gene causes change in Factor V protein making it resistant to inactivation by protein C –> increased propensity to clot by increased Factor V concentrations in blood [More…]
Facet joint arthropathy presents as localized lumbosacral back pain, without radicular neuropathic symptoms. The classic presentation for lumbar facet joint pain syndrome includes maximal pain directly over the joints, pain with palpation of facet joints, and referred pain. [More…]
Functional Residual Capacity. The amount of volume remaining in the lung after a normal exhalation. Lung Volumes: TLC = Total Lung Capacity [More…]
Variable decelerations are the most common type of decelerations and are transient decreases in fetal heart rate that characteristically vary in duration, shape/magnitude, and timing/onset. [More…]
90% of the citrate found in whole blood products is found in FFP and platelets (not PRBCs). Citrate chelates calcium (and magensium) (that is why it is used, to prevent clotting of store blood products) and this is the mechanism of citrate intoxication. [More…]
The fractional excretion of sodium, or FENA, is a calculated value used in the assessment of acute renal failure. It is an assessment of how much sodium is being excreted in the urine in comparison to how much total sodium the kidneys are “seeing” in the plasma.[More…]
The neuromuscular junction (NMJ) is a synapse between a presynaptic motor neuron terminal and a postsynaptic skeletal muscle fiber. Acetylcholine is released by the presynaptic neuron, diffuses across the synaptic cleft, and binds nicotinic acetylcholine receptors (nAChR) on the postsynaptic fiber. [More…]
The major pulmonary complication found in former -premature infants is post-operative apnea – post-operative apnea is a serious concern in the neonate, particularly if there is a history of prematurity, prior apneic episodes, bradycardia, congenital defects, anemia, or chronic lung disease (ex. respiratory distress syndrome). [More…]
The purpose of intraoperative evoked potentials is to monitor neural pathways in hopes of avoiding iatrogenic injury to the nervous system. Sensory evoked potentials (SEPs) evaluate the integrity of ascending sensory tracts while motor evoked potentials (MEPs) deal with the functionality of descending motor pathways. [More…]
There are multiple modalities currently used in practice to prevent paraplegia after aortic surgery including distal aortic perfusion, lumbar drains to monitor ICP and drain CSF, reimplantation of intercostal arteries, and moderate hypothermia. [More…]
Unconsciousness after intravenous etomidate results from binding to the GABA receptor and increasing its affinity for GABA. It has several cerebral vascular effects of note. Like most induction agents beside ketamine, cerebral metabolic rate and blood flow are both reduced. [More…]
Nonbarbiturate hypnotic, no analgesic activity, used for induction & sup of anesthesia. Decreases cerebral metabolism, cerebral blood flow, and intracranial pressure. (superior to propofol in maintaining cerebral perfusion pressure) Effects on EEG: initial increase α amplitude followed by progressive decrease in activity [More…]
Nitroglycerins (Isosorbide dinitrate, glycerylnitrate, itramintosylate, trolnitrate) Nitroprusside Anticholinergics (not when given with anticholinesterases) [More…]
Vasoconstrictors, such as epinephrine, can be added to local anesthetics. The addition of epinephrine causes multiple effects. [More…]
Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. [More…]
In a child presenting with acute epiglottitis, emergent airway management should be of primary concern. Once epiglottitis is suspected, further airway management should be coordinated between the pediatric anesthesiologist, otolaryngologist, and intensivist. [More…]
Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. [More…]
Some argue against doing a “test dose” because it lacks specificity and sensitivity for picking up an IT/IV epidural catheter placement. [More…]
Postoperative ileus is almost universal following major abdominal surgery. Nearly 100 years ago, Cannon and Murphy demonstrated that opening the peritoneal cavity and manipulating the intestines resulted in significant inhibition of GI tract contractile function in dogs. [More…]
Postoperative ileus is almost universal following major abdominal surgery. Nearly 100 years ago, Cannon and Murphy demonstrated that opening the peritoneal cavity and manipulating the intestines resulted in significant inhibition of GI tract contractile function in dogs. [More…]
Clonidine functions as a sympatholytic by stimulating presynaptic α2-receptors leading to decreased release of norepinephrine at both central and peripheral adrenergic terminals. In addition to its influence on the autonomic nervous system, it is well established that clonidine is an effective analgesic, and this is also attributable to its α2-agonist activity. [More…]
Dyspnea may occur due to proprioceptive blockade of afferent fibers from abdominal and chest wall muscles. Need to assess adequacy of ventilation then reassure the patient. [More…]
Complications of epidural analgesia can be broken down into three main categories: complications related to drug toxicity, complications related to needle/catheter placement, and exaggerated effects of appropriately injected drug. [More…]
Second, a major ARDS (Acute Respiratory Distress Syndrome) Network Trial—the OMEGA study– was recently published in JAMA (2, 3). The network conducted a phase 3 trial to study the efficacy of fatty acid/antioxidant supplementation in improving outcome in acute lung injury. [More…]
Drs. Aditee Ambardekar and John Mitchell discuss their article “The Anesthesiology Milestones 2.0: An Improved Competency-Based Assessment for Residency Training” from the August 2021 issue of Anesthesia & Analgesia.
Enoxaparin, like any LMWH, is derived by depolymerization of unfractionated heparin and retains UFH’s ability to activate antithrombin and thereby provide anticoagulation. [More…]
Originally introduced for colorectal surgery and subsequently expanded to include other surgical specialties, Enhanced Recovery After Surgery (ERAS) protocols aim to reduce hospital length of stay, cost, and complication rates while increasing patient comfort and satisfaction. [More…]
Shunt: During single lung ventilation, perfusion to the unventilated lung is still present. This leads to an intrapulmonary shunt and can precipitate hypoxemia. Protective mechanisms like hypoxic pulmonary vasoconstriction can help counteract the shunt, but only to a certain extent. Hypoxic pulmonary vasoconstriction can also exacerbate pulmonary hypertension. [More…]
Indications Endobronchial intubation to achieve one lung ventillation has absolute and relative indications. [More…]
The safe transfusion of blood and blood products is dependent upon antigen compatibility. Antigens on red blood cells are carbohydrate-based molecules that are recognized by antibodies. O, A, and B denote the antigens present on red blood cells. [More…]
Anesthetic options for an emergency cesarean include spinal, epidural, conversion of a labor epidural, a combined spinal-epidural (CSE), general anesthesia and local anesthesia. [More…]
Emergence delirium (ED) —a state of confusion, agitation, and restlessness—is seen with arousal from volatile agents at the completion of delivery of an anesthetic, and is a potentially dangerous phenomenon which has been associated with loss of central or peripheral access, self-extubation, and both patient and provider injury. [More…]
Factor treatment: 1. Prothrombin complex concentrate Prothrombin Complex Concentrate (PCC) (trade name Octaplex or Ocplex[1]) is a combination of blood clotting factors II, VII, IX and X, as well as protein C and S.[1] [More…]
Intracranial pressure (ICP) is determined by the volume of brain parenchyma (80%), blood (12%), and CSF (8%) within a rigid cranial vault. Normal ICP ranges from 5-15mmHg. [More…]
FRC = residual volume + expiratory reserve volume = volume of gas in the lungs after normal expiration [More…]
August 2021: Dr. Elisha Peterson and OpenAnesthesia Editor Dr. Jina Sinskey discuss perioperative management of the pediatric chronic pain patient.
Sodium levels are affected by ADH (hypothalamus), aldosterone (renin-angiotensin-aldosterone axis), glucocorticoids and mineralocorticoids (pituitary axis). [More…]
Vasopressin, also known as antidiuretic hormone (ADH), is a peptide hormone made in the hypothalamus and has both an immediate and long term effect on hemodynamics. [More…]
Rare autoimmune disorder, causes peripheral muscle weakness. Antibodies are directed against calcium channels at the neuromuscular junction. [More…]
The ex utero intrapartum treatment (EXIT procedure) involves partial delivery of the infant and maintenance of uteroplacental circulation long enough to secure the airway and provide potentially lifesaving interventions (bronchoscopy, tracheostomy, cannulation for ECMO) based on the condition of the neonate. [More…]
Rocuronium: Elimination half-time is increased by 37%; however, due to increased volume of distribution and plasma clearance in CRF, the duration of action is not significantly prolonged. [More…]
Goal Directed Fluid Therapy (GDT) is a tenant of ERAS protocols, utilizing an intra-arterial waveform for automated measurements of pulse pressure variations (PPV) or stroke volume variation (SVV) in order to determine response to fluid boluses. [More…]
EMLA (Eutectic Mixture of Local Anesthetics) is a eutectic mixture of lidocaine 2.5% and prilocaine 2.5% formulated as an oil in water emulsion developed to anesthetise intact skin. This eutectic mixture has a melting point below room temperature and therefore both local anesthetics exist as a liquid oil rather than as crystals. [More…]
Opioids produce a dose related decrease in the frequency and amplitude of the EEG. Low dose opioids show a loss of beta waves and a slowing of alpha waves. [More…]
The stimulus leads to increases in cerebral blood flow and increased ICP. Initially, the seizure activity causes a large parasympathetic discharge with bradycardia, atrial or ventricular premature beats, and occasional asystole. [More…]
ECT requires both general anesthesia and paralysis. Pretreatment with glycopyrrolate may reduce the incidence of bradycardia and decrease oral secretions following the initial parasympathetic response. [More…]
According to Miller, “Methohexital (0.75 to 1.0 mg/kg) is the most commonly used drug for ECT anesthesia and is considered the “gold standard” ,” although there are data to suggest that outcomes are no different between methohexital and propofol, despite the decreased seizure duration with propofol. [More…]
Electroconvulsive therapy (ECT) is an effective therapy for psychiatric disorders such as depression, mania, and affective disorders that have been refractory to standard medical therapy. [More…]
Before discussing contraindications, it is important to first understand the physiologic effects of ECT. These include : Large increases in cerebral blood flow and intracranial pressure [More…]
Cardiac Effects Following ECT stimulus Initial tonic phase is characterized by profound stimulation of the parasympathetic nervous system which can result in [More…]
When considering drug selection for ECT, several things should be carefully considered. 1. Induction of GA that allows for quick emergence after the seizure [More…]
External cardiac pacemaker function should not be affected by ECT because the current path is far from the heart. Patients with a history of CAD, CHF, and valvular heart disease may benefit from invasive monitoring to assess myocardial function and permit aggressive hemodynamic control. [More…]
If a lead becomes loose, you can get baseline wander TO REDUCE BASELINE WANDER: A) Use muscle relaxation [More…]
Definition: full-thickness separation of the uterine wall and the overlying serosa [More…]
In an adult the dural sac terminates caudally at S2 . The termination of the adult spinal cord, on the other hand, is at L1-2 and is called the conus medullaris. [More…]
The dura mater is the outermost of the spinal meninges. It is a thick, fibroelastic membrane composed of collagen and elastin fibers that is a continuation of the cranial dura. [More…]
Duchenne’s Muscular Dystrophy (DMD) is an x-linked recessive disease involving a mutation of the protein dystrophin. Dystrophin is found in skeletal, cardiac, and smooth muscle as well is in the brain, therefore manifestations follow suit. [More…]
Controlled hypotension is the process of deliberately reducing a patient’s blood pressure (typically, ~30% reduction of baseline MAP) for a therapeutic purpose. This is accomplished by reduction of either SVR or CO. [More…]
The immediate physiologic response to drowning is breath-holding. After breath-holding, involuntary laryngospasm can occur with entry of fluid into the oropharynx and larynx. [More…]
Doxorubicin is a chemotherapy drug that is administered intravenously. It is used in treatment of leukemia, lymphoma, breast cancer, soft tissue sarcoma, multiple myeloma, and other cancers. [More…]
Cardiotoxicity is the main one that everyone expects you to know but the list is long. Acute cardiotoxicity: Atrioventricular block, bradycardia, bundle branch block, ECG abnormalities, extrasystoles (atrial or ventricular), sinus tachycardia, ST-T wave changes, supraventricular tachycardia, tachyarrhythmia, ventricular tachycardia [More…]
Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. [More…]
Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. [More…]
Most common is the Robertshaw tube, available as both a L and R-sided tube. Sizes include a 28F (pediatric) as well as 35F, 37F, 39F, and 41F. All are PVC with D-shaped lumens, disposable. Blue represents the endobronchial lumen/cuff. Note that R-sided tubes have a donut-shaped endobronchial cuff, which allows separate access to the RUL. […]
Fast facts: Medical U/S detects at 1-20MHz, whereas the human ear detects sound at 20-20,000 Hz The speed that sound waves can move through a medium depends on the density and resistance of the medium [More…]
The Doppler shift occurs when a source of wave is moving toward or away from a receiver (or when the receiver is moving toward or away from a wave source). When the distance between a wave source and the receiver is getting smaller, the observed frequency of the wave is greater than the source frequency. […]
The liver is responsible for synthesis of clotting factors and other important proteins involved with regulating the coagulation cascade. Therefore, even in patients with a normal preoperative coagulation profile, alterations in bleeding and thrombosis have been observed following donor hepatectomy. [More…]
Pharmacologically, donepezil (Aricept®) is an acetylcholinesterase inhibitor. It is most active in the central nervous system, where it is used to increase levels of acetylcholine in patients with Alzheimer’s type dementia. [More…]
Loop Diuretics inhibit the Na+ K+ 2Cl- transporter in the thick ascending limb of the Loop of Henle. Due to their mechanism of action they may result in hypokalemia. [More…]
Sulfonamide derivatives Carbonic anhydrase inhibitors, such as acetazolamide, work at the proximal convoluted tubules to block the cleavage and subsequent resorption of bicarbonate to water and carbon dioxide. [More…]
Loop and thiazide diuretics can cause metabolic alkalosis due to increased excretion of chloride in proportion to bicarbonate. This is more common with loop diuretics than thiazide diuretics. [More…]
Discogenic pain stems from degenerative disk disease (DDD), occurring without spinal deformity, radicular pain, neurologic symptoms, or spinal stenosis. Often it arises from disruption of the posterior annulus fibrosis that causes an inflammatory response that activate nociceptive nerve terminals. [More…]
June 2021: Dr. Nina Deutsch and OpenAnesthesia Editor Dr. Debnath Chatterjee discuss the Society for Pediatric Anesthesia.
An adverse event is an undesirable outcome that results from an aspect of that patient’s clinical care and not from the underlying disease process. Over the past several decades, the medical community has increasingly embraced literature demonstrating the benefits to both providers and patients of disclosing adverse events. [More…]
Dilutional Coagulopathy refers to the coagulopathy seen during massive transfusion for major trauma and/or hemorrhaging. [More…]
Digoxin belongs to a class of drugs known as cardiac glycosides that (1) improves contractility and (2) decreases conduction velocity at the AV node. [More…]
Digoxin acts as an anti-arrhythmic and inotrope through reversible inhibition of cardiac Na/K ATPase pumps. This results in increased intracellular sodium and calcium and decreased intracellular potassium. [More…]
Difficult mask ventilation (DMV), defined as: “the inability of an unassisted anesthesiologist to maintain SpO2 >92%” is an uncommon but important scenario. [More…]
GA for C-section is most often done in an emergency situation (fetal distress, failed regional technique, high spinal, aspiration, cardiac arrest) and is associated with a higher mortality rate than regional techniques. [More…]
A differential block refers to the clinical phenomenon that nerve fibers with different functions have different sensitivities to local anesthetic blockade. [More…]
Dibucaine hydrocholoride is an amide local anesthetic, which when injected intravenously, can inhibit plasma cholinesterase or butyryl cholinesterase–the enzyme responsible for clearance of paralytics such as succinylcholine and mivacurium. [More…]
Croup, also known as laryngotracheobronchitis, is primarily subglottic. Viral etiology. History: Age typically 3 months to 3 years [More…]
Clinical Signs of Diabetic Autonomic Neuropathy: Hypertension Painless myocardial ischemia [More…]
I. What is DI? B. Nephrogenic DI – decrease in the ability to concentrate urine due to a resistance to ADH action in the kidney. – seen in chronic renal insufficiency, lithium toxicity, hypercalcemia, hypokalemia, and tubulointerstitial disease [More…]
Dexmedetomidine does not have direct cardiac action; however, it has several important indirect effects. A bolus dose of 1mcg/kg has a biphasic response – peripheral alpha 2 mediated vasoconstriction leading to transient increase in blood pressure, with a decrease in heart rate mediated by baroreceptor reflex. [More…]
MOA: central alpha-2 adrenergic agonist, acts on receptors in the brain (locus ceruleus) and spinal cord In the same class as clonidine but dexmedetomidine is more selective for alpha 2 receptors [More…]
Dr. Thomas Bein discusses his article “Invasiveness of Treatment Is Gender Dependent in Intensive Care: Results From a Retrospective Analysis of 26,711 Cases” from the June 2021 issue of Anesthesia & Analgesia.
von Willebrand’s disease is a hereditary deficiency of von Willebrand’s factor (VWF), causing platelet dysfunction. Bleeding tendency is usually mild. Screening tests show a normal platelet count and, possibly, a slightly prolonged PTT. [More…]
MOA: central alpha-2 adrenergic agonist, acts on receptors in the brain (locus ceruleus) and spinal cord In the same class as clonidine but dexmedetomidine is more selective for alpha 2 receptors [More…]
A full 16-lead, 8-channel electroencephalogram (EEG) is a recording of the electrical activity/potentials occurring in the cerebral cortex and can be used to monitor depth of anesthesia. EEG activity occurs mostly at frequencies between 1-30 Hz and can be broadly categorized into 4 wave patterns: alpha, beta, theta, and delta. [More…]
von Willebrand’s disease is a hereditary deficiency of von Willebrand’s factor (VWF), causing platelet dysfunction. Bleeding tendency is usually mild. Screening tests show a normal platelet count and, possibly, a slightly prolonged PTT. [More…]
Respiratory muscle weakness is common among patients who have neuromuscular disease. It can be acute (e.g., guillain-barré syndrome), chronic and relapsing (e.g., multiple sclerosis, myasthenia gravis), or relentlessly progressive (e.g., amyotrophic lateral sclerosis [als]). [More…]
Donor heart, which is completely denervated, does not respond to manipulations of the parasympathetic nervous system (including reductions in parasympathetic outflow, ex. anticholinergics, anticholinesterases, or increases on PNS outflow, ex. phenylephrine), or neuronal SNS outflow (ex. cardioaccelerator fibers, although systemic epinephrine may still affect the heart). [More…]
Hemolytic transfusion reactions can be defined as acute or delayed. Both are the result of recipient antibody and complement attack on donor cells. [More…]
Differential diagnosis of delayed emergence can be classified into one of three causes: drug effects, metabolic disorders, or neurologic disorders . If a patient doesn’t “wake” after an anesthetic you have to go down these three in that particular order. [More…]
Also known as extravascular hemolysis Generally mild and caused by antibodies to non-D antigens of the Rh system or to foreign alleles in other systems such as the Kell, Duffy, or Kidd antigens [More…]
Dantrolene is a hydrophobic, hydantoin derivative that suppresses the rate and amount of Calcium ions (Ca2+) released from the sarcoplasmic reticulum. Specifically, dantrolene inhibits RyR1-dependent cellular Ca2+ fluxes in skeletal muscle. [More…]
Dalton’s Law, simply stated, is that the total pressure exerted by a mixture of gases (real or ideal) in a fixed volume is equal to the sum of each gases partial pressure. Recall that the partial pressure of a gas is the pressure exerted by that gas on its container independent of any other gas. […]
Anesthesiologists in particular need to be aware that studies indicate that many patients with DNR orders in their charts (up to 46%) may be unaware that the order exists, even when they are competent. Documentation of discussion of DNR orders with the patient or appropriate surrogates must take place; anesthesiologists and surgeons should nevertheless approach […]
Stiff joint syndrome describes the triad of Type I diabetes mellitus, non-familial short stature, and stiff joints and/or joint contractures beginning approximately 10 years after diabetes onset. [More…]
Detection of a paced (VP) or sensed ventricular (VS) resets its clock an also initiates the ventricular refractory period (VRP) to prevent T-wave oversensing and initiates the post-ventricular atrial refractory period (PVARP) which helps prevent oversensing of retrograde P waves. [More…]
Dr. Debnath Chatterjee and Dr. Robin Deterding discuss the e-cigarette and vaping epidemic among adolescents in the U.S.
Pharmacokinetics is the study of how a drug is affected by the body (i.e. Absorption, distribution, metabolism, and excretion). Differences in genetic make-up alter a patient’s ability to respond to or metabolize a drug. Cytochrome P450 enzymes’ activities are governed by genetic polymorphisms resulting in phenotypes with varying abilities to perform their metabolic roles including […]
Cylinders stored on the back of anesthesia machines are E cylinders. The height of an E cylinder is 24.9 inches, the diameter of the base is 4.38 inches, and the empty weight is 5.90 kg. Both air and oxygen are stored as compressed gasses, and therefore the volume can be calculated if the pressure in […]
Treatment of cyanide toxicity should be initiated as soon as it is suspected; do not delay treatment while awaiting formal diagnosis by blood cyanide levels. Primarily, treatment is aimed at uncoupling cyanide from cytochrome oxidase , and allowing cells to return to aerobic metabolism via oxidative phosphorylation. [More…]
Cyanide toxicity causes uncoupling of oxidative phosphorylation, interrupting aerobic metabolism and forcing a shift to anaerobic metabolism, leading to decreased O2 consumption, elevated lactate and severe metabolic acidosis. [More…]
Crystalloid Crystalloids are solutions composed of sterile water with added electrolytes to give a composition similar to plasma. In general, crystalloids are used to replace fluid losses and to expand total extracellular volume. [More…]
Crystalloids and colloids are the primary options for intravenous fluid resuscitation. Crystalloids fluids such as normal saline typically have a balanced electrolyte composition and expand total extracellular volume. [More…]
Administration of large volumes of fluid deficient in platelets and clotting factors will predictably lead to the development of a coagulopathy as a consequence of dilution. There has been much research into whether patients first become deficient in platelets of clotting factors during massive volume resuscitation. In the end, this question is not likely to […]
One unit of Cryoprecipitate contains approximately 250 mg of Fibrinogen. Also, it is a VERY concentrated source of Factor 8 How is it prepared? by slowly thawing a unit of FFP at temperatures just above freezing (1-6 °C), typically in a water bath or a refrigerator. The product is then centrifuged to remove the majority […]
Nitrous Oxide is an anesthetic gas with a low potency with a MAC value of 104%. It is commonly used during mask inductions in pediatric patients, as an adjunct for labor analgesia, and in dentistry offices for conscious sedation. Among anesthetic gases, it has a unique physical chemical profile. [More…]
Positioning injuries associated with craniotomy are best considered by the position the patient will be in for the surgery. The risks of injury associated with each of the following patient positions are not necessarily exclusive to neurosurgical procedures. [More…]
After coronary artery stenting, patients are maintained on dual antiplatelet therapy (DAPT). When presenting for elective surgery, these medications are often held to minimize bleeding risk intraoperatively. The ideal timeframe to wait after stenting before proceeding with elective surgery is guideline based, and therefore does change periodically. [More…]
Coronary perfusion pressure is defined as the difference between systemic arterial pressure and intraventricular pressure. Because LV pressures equal or exceed systemic arterial pressures (as the LV is the source of systemic pressure some pressure drop occurs through the LVOT and aortic valve), left ventricular coronary perfusion is intermittent and only occurs during diastole. [More…]
May 2021: Dr. Robin Deterding and OpenAnesthesia Editor Dr. Debnath Chatterjee discuss the e-cigarette and vaping epidemic among adolescents in the US. Part 1.
Coronary Dominance: Dominance is determined by the coronary artery that crosses the junction between atria and ventricles to supply the posterior descending coronary branch. Though various estimates exist, Barash’s Clinical Anesthesia approximates that 50% of humans are right coronary artery dominant. [More…]
There are various other injuries that can cause heart block in a patient with MI or undergoing cardiac surgery. Damage to the distal RCA below the take-off of the AVNBA leading to RBBB or in a patient with pre-existing LBBB can lead to complete heart block but below the level of the AV Node manifesting […]
Corneal reflex: afferent = V1 branch of trigeminal nerve, efferent = facial nerve Steps: Pain receptors in cornea detect an irritating stimulus C fibers are activated Signal travels to cell bodies of C fibers in trigeminal ganglion, then via trigeminal sensory root à spinal trigeminal tract à spinal trigeminal nucleus of the pars caudalis [More…]
Adverse reactions to iodinated contrast agents may include contrast-induced nephropathy (CIN) or systemic reactions, which may either be immediate or delayed. [More…]
Prevention is key to function preservation, should focus on limiting risk factors which include : Creatinine greater than 1.5 mg/dL GFR < 60 ml/min [More…]
Dr. Haleh Saadat discusses her article “Effect of Inadequate Sleep on Clinician Performance” from the May 2021 issue of Anesthesia & Analgesia.
The context-sensitive half-time is the time required for blood or plasma concentrations of a drug to decrease by 50% after discontinuation of drug administration. [More…]
Context sensitive half-time is the time required to decrease the plasma concentration of a drug by 50% after termination of an infusion. It takes into consideration the multi-compartmental model of pharmacokinetics. [More…]
Stoelting’s Anesthesia and Co-existing Disease 5/e says: “A prominent y-descent of the jugular venous pressure (Friedreich’s sign) reflects the predominance of right ventricular filling in early diastole that is seen with constrictive pericarditis.” [More…]
Pulmonary hypertension (PHT) in Congenital Heart Disease (CHD) is a common problem. It can occur secondary to volume or pressure overload secondary to CHD or can develop after vascular injury related with cardiopulmonary bypass and lung injury. [More…]
A decrease in prostaglandin E2 (PGE2) , along with exposure to oxygenated blood, causes the ductus arteriosus to close after birth. [More…]
The concentration effect refers to the principle that the concentration of inspired anesthetic gas influences both (1) the alveolar concentration that may be attained and (2) the rate at which that concentration may be attained. [More…]
These can include: A complication seen with early versions of the Univent occurred when a fracture of the blocker cap connector was found. [More…]
Also known as third-degree AV block, complete heart block is a condition where there is dissociation between the electrical activity of the atria and ventricles. As a result, the two chambers contract independently with the ventricle in its own rhythm. [More…]
In a compensated respiratory acidosis, although the PCO2 is high, the pH is within normal range. The kidneys compensate for a respiratory acidosis by tubular cells reabsorbing more HCO3 from the tubular fluid, collecting duct cells secreting more H+ and generating more HCO3, and ammoniagenesis leading to increased formation of the NH3 buffer. [More…]
Compartment syndrome occurs when volume (usually edema and/or blood) accumulates in a confined osseofascial space to the extent that delivery of oxygen to tissues is compromised. [More…]
The gelatins decrease vWF, factor VIIIc, and ex vivo clot strength. Despite these decreases, they still have the smallest impact of the synthetic colloids on hemostasis. Nevertheless, gelatins have the highest rate of anaphylactic and anaphylactoid reactions. These are used in Europe but are not approved for use in the US. [More…]
Cocaine Intoxication: Cocaine is an ester local anesthetic derived from coca leaves that is readily absorbed via mucosal surfaces in oral, nasal, or pulmonary alveoli. Today, it is most often used as a drug of abuse but was originally used in eye surgery as a local anesthetic. [More…]
The risk of developing a venous thromboembolism increases about 100-fold when a parturient is admitted to a hospital and also seems to be worse during the third trimester. This is thought to be due to changing hormonal levels, in particular increased estrogen as pregnancy progresses. [More…]
Considerations in the perioperative period: FFP 10-20 ml/Kg should correct PT to near normal for 12-24h [More…]
ASA closed malpractice claims data to identify areas of morbidity, mortality and prevention thereof started in 1985. It is overseen by the Committee on Professional Liability of the ASA. [More…]
The power of a statistical test is the probability that the test will reject a false null hypothesis (that it will not make a Type II error). As power increases, the chances of a Type II error decrease. [More…]
The Clark electrode was invented by Leland Clark after criticism that his bubble oxygenator, which he had invented for use in cardiac surgery, was unable to measure the oxygen tension of the blood returning to the patient from the bypass circuit. [More…]
Citrate is used to prevent coagulation of stored blood products (primarily FFP and platelets, as well as cell saver). Citrate chelates calcium and magnesium, leading to hypocalcemia and hypomagnesemia when large amounts are transfused (greater than 6 units/hr in adults). [More…]
Synthetic function of liver include: Synthesis of plasma proteins Acute phase proteins Albumin [More]
During hypothermia, pH-stat (reporting of blood gases at body temperature) corrects for the effects of temperature on pH in order to keep the pH static (7.4). [More…]
Unlike benign pain, usage of opioids in chronic pain management elicits little controversy. Nevertheless, there is significant disagreement in drug choice, timing, and dosage leading to significant practice variance. [More…]
Morphine and methadone are both opioids used in pediatric pain management. Morphine is more protein bound in adulthood than during the neonatal period (30% vs 20%). Morphine is metabolized to morphine 3-glucoronide and morphine 6-glucoronide. [More…]
Back pain is the most common cause of discomfort and disability in the United States. Sources of pain may be multiple, and include: intervertebral discs, vertebral bodies, facet joints, nerve roots, surrounding muscles/ligaments and abdominal/pelvic viscera. [More…]
Local anesthetics are weakly basic drugs that are principally bound to 1-acid glycoprotein. Placental transfer depends on three factors: (1) pKa, (2) maternal and fetal pH, and (3) degree of protein binding. [More…]
This is a test used to evaluate an hypothesis by comparing measured results to theoretically expected results (i.e. the Null hypothesis). [More…]
Chi-square test for categorical variables determines whether there is a difference in the population proportions between two or more groups. In the medical literature, the Chi-square is used most commonly to compare the incidence (or proportion) of a characteristic in one group to the incidence (or proportion) of a characteristic in other group(s). [More…]
Chest wall compliance is the opposite of elasticity, and elasticity is the tendency of lung tissue to return to its original (or relaxed) position after an applied force has been removed. [More…]
Cervical Precaution According to Barash, chapter 36, “Maintenance of immobilization of the injured spine is of paramount importance. [More…]
Cerclage, or surgical reinforcement of the cervix, is primarily used to prevent preterm birth in patients with cervical insufficiency. [More…]
Cerebral blood flow (CBF) is directly proportional to cerebral metabolic rate (CMR). Cerebral perfusion pressure (CPP) is the difference between the mean arterial pressure (MAP) and intracranial pressure (ICP) or central venous pressure (CVP), whichever is greater. [More…]
In the aftermath of subarachnoid hemorrhage, when nimodipine & HHH fail to avert cerebral vasospasm, balloon angioplasty may be performed to forcibly dilate constricted vessels & restore perfusion to the affected (ischemic) brain regions. [More…]
Cerebral Palsy represents a large spectrum of symptoms usually stemming from an injury to the developing brain which impairs various neurological functions and has wide ranging sequelae across many organ systems (e.g. mild monoplegia to spastic quadriplegia; normal cognition to severe MR). [More…]
Cerebral ischemia can occur hours after DHCA, because CBF and CVR are deranged for several hours after temperatures return to normal. [More…]
Under normal circumstances, cerebral blood flow (CBF) is approximately 50 mL/100 g/min. Gray matter receives 80% and white matter receives 20% of this blood flow. [More…]
Cerebral autoregulation may be defined as the maintenance of constant cerebral blood flow despite changes in cerebral perfusion pressure, where CPP is equivalent to MAP-ICP (or CVP, whichever is greater). [More…]
Increased neuronal activity results in increased local brain metabolism which in turn is associated with a proportional increase in cerebral blood flow (CBF). This mechanism, referred to as flow-metabolism coupling, is regulated by metabolic, glial, neural, and vascular factors. [More…]
The transmural pressure of an aneurysm is related to the difference between the Mean Arterial Pressure (MAP) and Intracranial Pressure (ICP): Transmural Pressure= CPP= MAP – ICP [More…]
Aneurysmal subarachnoid hemorrhage occurs in approximately 1 per 10,000 persons in the United States every year, accounting for 5–15% of all strokes. [More…]
The majority of direct acting vasodilating agents (i.e. hydralazine, sodium nitroprusside, nitroglycerin, and calcium channel blockers) cause an increase in cerebral blood volume. [More…]
Dr. Debnath Chatterjee discusses his article “Anesthesia for Maternal–Fetal Interventions: A Consensus Statement From the American Society of Anesthesiologists Committees on Obstetric and Pediatric Anesthesiology and the North American Fetal Therapy Network” from the April 2021 issue of Anesthesia & Analgesia.
Anesthetic goals in this patient population revolve around 1) preventing large changes in blood pressure 2) facilitating surgical exposure [via hyperventilation and osmotic diuresis] 3) ensuring adequate collateral circulation if temporary clips are placed during surgery 4) minimizing deleterious increases in ICP and 5) allowing for rapid wakeup and neurologic examination. [More…]
Knowledge of CVC kits, anatomy, and proper insertion technique are critical to the success of central venous cannulation. The most common insertion sites are the internal jugular vein, subclavian vein, and femoral vein. [More…]
DEFINITION: is when you repeatedly stop breathing during sleep because the brain temporarily stops sending signals to the muscles that control breathing. (vs OSA which is due to upper airway obstruction). [More…]
Employ aseptic technique during placement, which includes full sterile drape, sterile gown and gloves, hat and mask . Use the subclavian vein when possible (although direct comparisons of SC and IJV have not been made). [More…]
The celiac plexus is the largest plexus of the sympathetic nervous system. It contains preganglionic sympathetic fibers from greater and lesser splanchnic nerves (emerge from the thoracic sympathetic ganglia, T5 to T12 ) as well as postganglionic sympathetic and preganglionic parasympathetic fibers. [More…]
The celiac plexus is the largest plexus of the sympathetic nervous system. It contains preganglionic sympathetic fibers from greater and lesser splanchnic nerves (emerge from the thoracic sympathetic ganglia, T5 to T12 ) as well as postganglionic sympathetic and preganglionic parasympathetic fibers. [More…]
Cerebral blood flow and cerebral metabolic rate (normally 3.0-3.8 ml O2/ 100gm brain/min) are coupled in the absence of pathology and or various anesthetic drugs. This means when cerebral metabolic rate increases or decreases so does cerebral blood flow. [More…]
Upregulation of Acetylcholine receptors leads to increased sensitivity to Succinylcholine and risk for hyperkalemia due to depolarization of the muscle membrane. [More…]
March 2021: Dr. Teeda Pinyavat and OpenAnesthesia Editor Dr. Aditee Ambardekar discuss malignant hyperthermia and the MH Hotline.
Caudal Block is a technique most commonly utilized in neonates, infants and small children (typically
Caudal epidural block involves injection of medication through the sacral hiatus, which is an arch shaped opening in the dorsal sacral surface. [More…]
Categorical data is also known as nominal data, meaning that one uses labels as opposed to numbers; for example, race and gender are categorical variables. [More…]
Carotid surgery typically requires temporary occlusion of the internal carotid artery. This would almost certainly result in a large stroke if the parts of the brain supplied by the occluded internal carotid artery were not adequately perfused by collateral circulation. [More…]
During carotid angioplasty and stenting, a tiny balloon is inserted to widen the lumen of a stenotic carotid artery, and small metal stent is placed to prop it open and decrease the chance of restenosis. During and after this procedure, the normal carotid baroreceptor reflex mechanism may produce a physiologically-inappropriate response. [More…]
During carotid angioplasty and stenting, a tiny balloon is inserted to widen the lumen of a stenotic carotid artery, and small metal stent is placed to prop it open and decrease the chance of restenosis. During and after this procedure, the normal carotid baroreceptor reflex mechanism may produce a physiologically-inappropriate response. [More…]
Carotid sinus reflex can be used therapeutically to produce vagal stimulation that may be an effective treatment for supraventricular tachycardia. [More…]
Several randomized controlled trials have proven benefit of this procedure in symptomatic patients with 70-99% stenosis. Different sources quote risk of stroke or death associated with CEA as anywhere from 1 to 7%. [More…]
The carotid bodies are chemosensitive cells at the bifurcation of the common carotid that respond to changes in oxygen tension and, to a lesser extent, pH. in contrast to central chemoreceptors, which primarily respond to PaCO2 and the aortic bodies [output via cn X], which have primarily circulatory effects (bradycardia, hypertension, adrenal stimulation, and also […]
CEA requires temporary clamping of the carotid artery being worked on rendering the ipsilateral hemisphere dependent on collateral flow from the vertebral arteries and the contralateral carotid artery through the Circle of Willis. [More…]
Goals of Cardiopulmonary Bypass Management of Physiology Ideal perfusion pressure not known. Cerebral autoregulation from 50-150 mm Hg. Confounded by chronic HTN, advanced age, diabetes. May be as low as 20 mm Hg when hypothermic. Excess perfusion may increase the risk of embolism. [More…]
Blood temperature is typically measured either by a thermistor on the end of a PA catheter, or by the bypass machine itself. This temperature is the quickest to change, as heat is added or removed by the perfusionist directly to the blood. [More…]
Cardiac tamponade is a clinical syndrome resulting from the accumulation of fluid in the pericardial space resulting in reduced ventricular filling and subsequent cardiovascular compromise. The diagnosis of cardiac tamponade is made clinically, not with imaging. [More…]
The pericardial sac typically has 15-30 ml fluid. Cardiac tamponade is caused by an increased amount of fluid in the pericardial sac, which compresses the heart. [More…]
Diagnosis of cardiac tamponade relies mainly on index of suspicion especially for patients who are at risk for acute cardiac tamponade physiology (those who have recently had cardiac surgical procedures, electrophysiology procedures). [More…]
Dr. Jina Sinskey discusses her article “Pediatric Distraction on Induction of Anesthesia With Virtual Reality and Perioperative Anxiolysis” from the March 2021 issue of Anesthesia & Analgesia.
In general terms, most patients presenting for a subxiphoid pericardial window should undergo the procedure under local anesthesia with spontaneous ventilation and as little sedation as possible. If local anesthesia cannot be performed (or if tamponde occurs during a general anesthetic), the following principles should guide management. [More…]
Auscultatory Zones Aortic: RUSB (right upper sternal border) Pulmonic: LUSB (left upper sternal border) Tricuspid: 4LICS (4th left intercostal space), on the sternal border Mitral: 5 LICS (5th left intercostal space), several cm lateral to the 4LICS [More…]
Perioperative indications for pacemaker placement: any documented symptomatic bradyarrythmia a new bundle branch block a second degree type II aV block< [More…] /li>
Developed by Adolf Fick, the Fick Principle can determine cardiac output if an investigator knows what amount of a substance is taken up by an organ (or whole body) in a unit of time, the concentration of the substance in the arterial blood supplying the organ (or whole body), and the concentration of the venous […]
Risk factors are: history of ischemia or heart disease, CHF, CVA, Cr > 2.0, IDDM, high risk surgery [Lee et al.] [More…]
Diastole is divided into four phases and comprises 2/3 of the cardiac cycle. It begins when the aortic valve closes. This is the start of Isovolumic Relaxation (volume remains constant but the pressure in the ventricles fall).[More…]
In 2002, two large, prospective trials demonstrated that mild hypothermia after resuscitation from cardiac arrest and maintained for 12 to 24 hours improved survival and neurologic outcome in patients suffering from VF/VT arrest. [More…]
Preoperative cardiac evaluation of valvular disease helps identify the severity of the valvular defect, the hemodynamic changes from the valvular lesion, and changes in the pulmonary, renal, and hepatic systems as a result from the aberrant valve. [More…]
The principle ions involved in the cardiac cycle are sodium, potassium, and calcium. There are two different clinically significant forms of cardiac action potentials and resulting ion movement: 1.) SA node and 2.) Atria, ventricles, and Purkinje system. [More…]
Block of the Month will be back soon with more content. See the archive here: Block of the Month
Background Beyond the first 6 months of life, hemoglobin A, a tetramer composed of 2 α- and 2 β-globin chains, is the predominant form of human hemoglobin. A single nucleotide substitution in the β-globin gene results in the replacement of glutamic acid with valine at the sixth amino acid position of the β-chain and imparts […]
Carcinoid tumors release a variety of subtances (ex. serotonin, catecholamines, histamine) which can cause both hypertension and hypotension. [More…]
Normal individuals will have up to 3% CO, and smokers may have up to 9% . Patients are generally asymptomatic if < 10%, with overt signs developing at ~ 15%. [More…]
Capnothorax is a type of pneumothorax where carbon dioxide occupies space in the pleural cavity preventing full inflation of the lung. Capnothorax is suspected in the setting of abdominal laparoscopic surgery when CO2 is used for insufflation and the procedure involves manipulation of the diaphragm as in esophageal surgery. [More…]
February 2021: Dr. Zeev Kain and OpenAnesthesia Editor Dr. Jina Sinskey discuss perioperative anxiety in children.
Hyper-/Hypocalcemia can cause ECG changes secondary to altered trans-membrane potentials that affect conduction times. (Sources 1,2). Hypercalcemia : The most common ECG findings of hypercalcemia are a short QT interval (Ref. 1) secondary to a shortened ST segment. [More…]
Calcium channel blockers are among the list of drugs found to prolong neuromuscular blockade (others include: aminoglycosides, tetracyclines, polymyxins, anticholinesterases, local anesthetics, and volatile anesthetics). [More…]
CVP is generally measured at the junction of the superior vena cava and the right atrium. This is most commonly this is done via a central venous catheter placed through the right internal jugular vein. A normal CVP waveform contains five components. [More…]
It is considered standard of care to obtain a chest x-ray after placing a central line in order to exclude complications such as pneumothorax and also to confirm proper placement. [More…]
Prevention of central venous catheter (CVC) infections has become an important patient safety and quality improvement measure over the last decade. [More…]
Mixed venous saturation can help assess tissue oxygen delivery. By using the derivation of the Fick equation, the mixed venous saturation can be determined by: SvO2 = SaO2 – [(VO2) / (Hb x 1.36 x Q)] [More…]
Capnography directly reflects the elimination of CO2 by the lungs to the anesthesia device. It indirectly reflects the production of CO2 by tissues and the circulatory transport of CO2 to the lungs [More…]
A pressure-volume (PV) loop for the left ventricle is generated as left ventricular pressure is plotted against left ventricular volume at multiple time points during a complete cardiac cycle. [More…]
Vasopressin acts directly via V1a receptors to cause vasoconstriction. This occurs most strongly in peripheral arterioles as well as in the vasculature of the heart, brain, and kidneys. [More…]
Elderly patients have an increased incidence of heart failure and cardiomyopathy. This is in part due to the increased incidence of ischemic coronary artery disease, hypertension, and diabetes leading to cardiomyopathy. [More…]
Complex regional pain syndrome (CRPS), is a regional, posttraumatic, neuropathic pain problem that most often affects one or more limbs. Like most medical conditions, early diagnosis and treatment increase the likelihood of a successful outcome. [More…]
The norm for cardiopulmonary bypass (CPB) priming solution is crystalloid. Although there is institutional variation, it generally has a similar electrolyte content and osmolarity as plasma. [More…]
One of the most deleterious complications of cardiopulmonary bypass is an embolism. Gas embolism is specifically a concern as it relates to the oxygenator. [More…]
Anitfibrinolytics are frequently used in patients placed on CPB. The two available lysine analogs, ε-aminocaproic acid and tranexamic acid , bind to lysine binding sites on plasminogen and fibrinogen and thereby inhibit plasminogen activator and plasmin release. [More…]
Carbon dioxide is transported in blood in three forms: dissolved in plasma, as bicarbonate, and coupled to proteins in the form of carbamino compounds. [More…]
The chemical control of breathing is based on a negative feedback loop and chemoreflex. Thus, when the central and peripheral chemoreceptors sense an increase in [H+], breathing is stimulated by a chemoreflex that includes the central nervous system, respiratory muscles, and changes in alveolar ventilation, resulting in correction of the [H+], hence the negative feedback […]
The circle system is the most popular breathing system in the US. The circular design includes the following components: (1) a fresh gas inlet; (2) an inspiratory unidirectional valve and inspiratory breathing tube [More…]
Describes the relationship between PCO2 and total CO2 concentration in blood. Three Forms of Carbon Dioxide in the Blood 1. Physically dissolved CO2 (~5%) [More…]
Issue : Desiccated (or dry) CO2 absorbers such as soda lime and Baralyme can degrade inhaled anesthetics to carbon monoxide, and my produce carboxyhemoglobin concentrations in excess of 30%. [More…]
Mechanism : These CO2 absorbers contain strong bases (sodium hydroxide and potassium hydroxide) that can extract labile protons from anesthetic molecules, resulting in the production of CO. [More…]
Issue : Desiccated (or dry) CO2 absorbers such as soda lime and Baralyme can degrade inhaled anesthetics to carbon monoxide, and my produce carboxyhemoglobin concentrations in excess of 30%.[More…]
Decreasing afterload with vasodilators can improve stroke volume and ejection fraction because the afterload is often elevated in heart failure and these drugs can increase stroke volume and decrease preload. [More…]
The intrinsic property of myocardium to increase the force of contraction in relationship to the stretch of cardiac muscle is the Frank-Starling relationship. This relationship is commonly used to describe the influence of ventricular end-diastolic volume (LVEDV or preload) on stroke volume (SV) and is illustrated to the left. [More…]
Skin Preparation: • Catheter insertion site should be cleaned with an antiseptic (70% alcohol, tincture of iodine, an iodophor or chlorhexidine gluconate) before peripheral venous catheter insertion. [More…]
Normal cerebral blood flow (CBF) is 50 mL / min / 100g of brain tissue. Grey matter receives 80% of cerebral blood flow whereas white matter receives the remaining 20%. Factors that affect CBF include cerebral metabolic rate, autoregulation, reactivity to CO2 and O2, temperature, vasoactive drugs, and anesthetic agents. [More…]
Compared to the planned vaginal delivery group, the planned cesarean group had a significantly higher postpartum risk of: cardiac arrest (Odds Ratio 5.1) [More…]
Butyrylcholinesterase (pseudocholinesterase) is a serine hydrolase synthesized in the liver and present in the plasma. It is structurally and functionally related to acetylcholinestrase, an enzyme that is that catalyzes the hydrolysis of acetylcholine. [More…]
January 2021: Dr. Diane Gordon and OpenAnesthesia Editor Dr. Debnath Chatterjee discuss environmental sustainability.
Succinylcholine is composed of two molecules of acetylcholine. It binds to and stimulates cholinergic receptors at neuromuscular junction (1 mg/kg causes suppression of response to neuromuscular stimulation within 60 seconds). [More…]
Pharmacologic neuroprotection/burst suppression has been of great interest for decades in the setting of acute cerebral insults. [More…]
Normal individuals will have up to 3% CO, and smokers may have up to 9% . Patients are generally asymptomatic if < 10%, with overt signs developing at ~ 15%. More…
What are indications for Mechanical Ventilation? clinical or laboratory signs that the patient cannot maintain an airway or adequate oxygenation or ventilation. More…
Bronchospasm: Cause Bronchospasm is is a reversible reflex spasm of the smooth muscle in the bronchi. [More…]
A core function of the upper airway is to protect the lungs from aspiration via various reflexes, one of which is bronchospasm, or the temporary narrowing of the bronchi via involuntary contraction of the local smooth muscle. [More…]
Dr. Mark Burbridge discusses his article “Incidence of Anaphylaxis to Sugammadex in a Single-Center Cohort of 19,821 Patients” from the January 2021 issue of Anesthesia & Analgesia.
Minimally invasive direct coronary artery bypass (MIDCAB) originally describes LIMA takedown and anastomosis to the LAD via anterior thoracotomy, as performed either off-pump on on-pump with femoral CPB cannulation. [More…]
rupture of a bronchus, bulla, cyst, or abscess erosion due to carcinoma or inflammatory disease stump dehiscence status post pneumonectomy [More…]
Bronchial blockers can be advantageous in patients in whom intubation with a double lumen tube is difficult or impossible (easier to place, can ventilate while placing). [More…]
The three ketone bodies are acetone, acetoacetic acid, and beta-hydroxybutyric acid. Ketone bodies are derived from the incomplete oxidation of fatty acids in the liver and are used for energy (ATP generation) in the heart and brain. [More…]
Ancillary tests, such as Transcranial Doppler, Cerebral Angiography, CTA, MRA, Nuclear Med, Somatosensory Evoked Potentials and EEG, are available if confounding factors are present and in some countries they are required in addition to the clinical exam. [More…]
Perioperative and post-operative bradycardia is relatively common during and after heart transplant. Possible etiologies including sympathetic denervation, ischemic injury to the sinus node, and graft ischemia. [More…]
The brachial plexus is formed by the union of the anterior primary divisions of the 5th-8th cervical nerves and the 1st thoracic nerve [More…]
Botulinum A Toxin is produced by Clostridium botulinum which affects the presynaptic membrane of the neuromuscular junction where it prevents acetylcholine release and therefore muscle contraction. Inactivation persists until collaterals form in junction plates on new areas of muscle cell walls. [More…]
Cross-matchinging is performed to determine if donor blood cells will be compatible with an intended recipient. It usually takes about 1 hour to perform. [More…]
The Blood Gas Partition Coefficient is also known as Ostwald coefficient for blood–gas. A partition coefficient is the ratio of the concentrations of a compound in one solvent to the concentration in another solvent at equilibrium. [More…]
Bi-ventricular (“bi-vent”) pacing falls under the larger category of Cardiac Resynchronization Therapy (CRT) with the primary goal of resynchronizing both ventricles through simultaneous pacing. This can improve myocardial contractile function, reduce functional MR, and reverse cardiac remodeling associated with heart failure. [More…]
The Bland Altman Plot (also known as the Mean-difference plot) is a statistical method of comparing two measurements of the same variable (for example, comparing invasive blood pressure measurement and non-invasive blood pressure measurement). [More…]
According to Miller, “bilateral recurrent laryngeal nerve injury and resultant bilateral vocal cord paralysis can result in life-threatening upper airway obstruction. This situation must be anticipated in patients who have previously undergone contralateral carotid endarterectomy or neck surgery…[More…]
Bier block, also known as “Intravenous Regional Anesthesia” or “IVRA” was invented by August Bier in 1908 and has been most commonly used for short duration procedures of the upper extremity distal to the elbow. A Bier block is performed by inserting a small gauge IV as distal in the operative extremity as possible. [More…]
Thalassemia is a disorder of production of one of the proteins of hemoglobin. Hemoglobin is a protein in red blood cells and is responsible for the transport of oxygen to tissues. Hemoglobin is made up of two proteins, alpha globin and beta globin.[More…]
Bronchodilation due to administration of beta-agonists is specifically related to their action at the β2-adrenoceptors. The efficacy of β2-agonists for patients with asthma and COPD results from a direct relaxation of airway smooth muscle and a secondary reduction of inflammatory cell activation. [More…]
Upregulation refers to an increase in the density of beta-adrenoceptors on the surface membranes and is modulated by a multitude of pharmacologic and pathophysiologic factors. [More…]
Muscular dystrophy is a group of hereditary diseases characterized by painless degeneration and atrophy of skeletal muscles. There is symmetric skeletal muscle weakness/wasting without denervation (sensation and reflexes are intact). [More…]
Bariatric surgery or weight loss surgery includes multiple procedures for morbidly obese patients. Bariatric surgery is typically reserved for patients with a BMI > 40 or BMI >35 with obesity related complications. [More…]
Pharmacokinetics – or what the body does with a drug – involves drug absorption, volume of distribution, metabolism (and half-life), and clearance. [More…]
Barbiturates (except for the less-soluble phenobarbital) are mainly metabolized by the liver into inactive, water-soluble compounds by oxidation and then are renally excreted or conjugated to glucuronic acid and excreted in bile. [More…]
Current indications for pharmacologic burst suppression based on low level evidence include : Refractory Status Epilepticus (6), Refractory Intracranial Hypertension (such as in traumatic brain injury) (7), and Intraoperative Neuroprotection during cerebrovascular (such as carotid endarterectomy) surgery (8). [More…]
The Bainbridge Reflex describes an increase in heart rate in response to increased central venous pressure. It is classified as one of several cardiac reflexes, which detect and respond to various physiologic states. [More…]
The axillary approach to the brachial plexus is associated with a very low complication rate, providing intravascular injection is avoided. [More…]
at the level of the axilla, the nerves are in their terminal branches the median, ulnar and radial nerves lie around the axillary artery and are blocked with a single injection. the musculocutaneous nerve however lies lateral to the axillary artery in the coracobrachialis muscle and requires a separate injection [More…]
During the axillary approach to the brachial plexus, the block is performed in the axilla, where large terminal branches have formed. [More…]
An axillary block is often used for forearm or hand surgery. Local anesthetic is injected around the axillary artery, as the nerves of interest lie in close proximity. The patient is positioned in the supin position with the arm abducted 90°. [More…]
Awareness results partly from the inability to accurately measure the depth of anesthesia. There is no monitor that can guarantee no intraoperative awareness/recall. [More…]
Acute blood loss leads to decreased cardiac output, tachycardia, hypotension, and hypovolemic shock. Inadequate organ perfusion and oxygen delivery interfere with aerobic metabolism. [More…]
The autonomic nervous system is made up of 2 subdivisions: sympathetic and parasympathetic systems. The sympathetic system originates from the thoracolumbar regions (T1-L2) of the spinal cord. The parasympathetic system originates from craniosacral regions (brainstem nuclei CN III, VII, IX, and X as well as sacral levels S2-S4). [More…]
December 2020: Dr. Rita Agarwal and OpenAnesthesia Editor Dr. Aditee Ambardekar discuss pediatric anesthesia and the safety of children undergoing dental work.
In a patient with a spinal cord injury (SCI), autonomic hyperreflexia (autonomic dysreflexia) is initiated by noxious stimuli below the level of cord injury. The noxious stimuli elicits a hypertensive response, which is followed immediately by a profound vagal response. In response to the increase in afterload, patient may vasodilate and appear flushed above the […]
Patients with a spinal cord injury at T7 or higher are at risk for autonomic hyperreflexia. Normally, the reflexic response to cutaneous, visceral (bladder), and proprioceptive stimuli are to some extent attenuated by descending, inhibitory impulses. [More…]
The sympathetic nervous system originates from T1-L2/3. Preganglionic SNS fibers to the upper extremity originate in the first four or five thoracic segments, and synapse in the superior, middle, and inferior (stellate) cervical ganglia. [More…]
Patients with a spinal cord injury at T7 or higher are at risk for autonomic hyperreflexia. Normally, the reflexic response to cutaneous, visceral (bladder), and proprioceptive stimuli are to some extent attenuated by descending, inhibitory impulses. [More…]
Initial treatment of atrial flutter targets the rate control (which is frequently ~150 BPM). Drugs of choice include beta blockers such as esmolol (0.5 mg/kg IV bolus followed by 50-300 ucg/kg/min) and propranolol, or calcium channel blockers such as verapamil (5-10 mg IV) or diltiazem. [More…]
The presence of atelectasis during the perioperative period is likely a multifactorial process. Possible etiologies include the following: 1. Compression : The properties of the thorax and lung change leading to decreased compliance and decreases FRC (decreased by 1 L supine + 0.4 L during general anesthesia). [More…]
The first sign of salicylate toxicity is often hyperventilation and respiratory alkalosis due to medullary stimulation. Metabolic acidosis follows , and an increased anion gap results from accumulation of intracellular lactate as well as excretion of bicarbonate by the kidney to compensate for respiratory alkalosis. [More…]
The patient should be placed in the head-down position, oxygen 100% administered, anesthesia deepened, suctioning performed and the severity of the regurgitation/aspiration event assessed fibreoptically. [More…]
Ascites imposes a restrictive load on the thoracic cage indirectly by the additional weight caused by abdominal swelling from intraperitoneal fluid. This additional load impedes movement of the diaphragm when these patients are in the supine position. [More…]
December 2020 Dr. Sara Goldhaber-Fiebert discusses her article “Clinical Uses and Impacts of Emergency Manuals During Perioperative Crises” from the December 2020 issue of Anesthesia & Analgesia.
The first sign of salicylate toxicity is often hyperventilation and respiratory alkalosis due to medullary stimulation. Metabolic acidosis follows , and an increased anion gap results from accumulation of intracellular lactate as well as excretion of bicarbonate by the kidney to compensate for respiratory alkalosis. Initial ABG testing often reveals this mixed respiratory alkalosis and […]
Bellows are classified according to their movement during EXPIRATION. Ascending bellows rise during expiration and descending bellows fall during expiration. [More…]
As the arterial pressure wave travels from the central aorta to the periphery, the arterial upstroke becomes steeper, the systolic peak becomes higher, the dicrotic notch appears later, the diastolic wave becomes more prominent, and end-diastolic pressure becomes lower. [More…]
Arterial pressure waveform can be utilized for goal-directed fluid management as it provides a representation of where the patient lies on the Starling curve. The Frank-Starling curve is an illustration that compares left-ventricular diastolic pressures or preload on the X-axis to stroke volume on the Y-axis. [More…]
Arginine vasopressin or antidiuretic hormone (ADH) is a nonpeptide hormone that is essential for volume homeostasis. It is synthesized in the magnocellular neurosecretory neurons in the paraventricular nucleus and supraoptic nucleus of the hypothalamus and transported down the hypothalamoneurohypophyseal tract to be stored in the posterior pituitary gland. [More…]
Vasopressin (also, anti-diuretic hormone (ADH) or arginine vasopressin (AVP)) has been shown to be a very effective vasopressor, especially in circumstances where patients are vasopressin depleted and have become reliant on catecholamines for blood pressure regulation. [More…]
Arginine vasopressin, vasopressin, or Anti Diuretic Hormone (ADH) is a peptide hormone which is synthesized in the supraoptoic nucleus of the hypothalamus. It is transported down the infundibulum and is stored in secretory vesicles in the posterior pituitary. [More…]
Aortic stenosis is the most common cardiac valve lesion in the United States. The underlying cause is progressive calcification and sclerosis of the aortic valve leaflets, due either to a congenital condition (Bicuspid Aortic Valve is found in 1-2% of the population), or as a natural part of the ageing process. [More…]
Aortic insufficiency produces volume overload of the LV and the effective forward SV is reduced due to the backward flow of blood into the LV during diastole. With chronic AI, the LV progressively dilates and undergoes eccentric hypertrophy. [More…]
Aortic insufficiency (AI) or regurgitation (AR) may be acute or chronic in nature. Infective endocarditis involving the aortic valve, trauma to the aortic valve and acute aortic dissection are well-described causes of acute AR. The etiologies of chronic AR include connective tissue diseases such as Marfan syndrome and Ehlers-Danlos syndrome, bicuspid aortic valve, and other […]
Complications : If the cross-clamp is suprarenal, can have renal failure, hepatic ischemia and coagulopathy, bowel infarction, and paraplegia. Most consistent response is arterial hypertension above the clamp and hypotension below the clamp. [More…]
Surgery on the descending aorta almost always involves the application of a cross-clamp so the surgeon is able to sew a graft to it. As a general rule, the more proximal the clamp is placed to the heart, the greater amount of stress it places on the heart. [More…]
Laboratory testing for coagulation studies are commonly performed in a light blue top tube, which has 3.2% sodium citrate added in a specific amount to prevent coagulation of the blood. [More…]
Neostigmine, pyridostigmine, and edrophonium are primary excreted via both glomerular filtration and active tubular secretion. Neostigmine is water-soluble and roughly 50% of it undergoes renal excretion compared to 75% of pyridostigmine and edrophonium. [More…]
Organophosphate compounds are used as commercial insecticides (isulfoton, phorate, dimethoate, ciodrin, dichlorvos, dioxathion, ruelene, carbophenothion, supona, tepp, epn, hetp, parathion, malathion, ronnel, coumaphos, diazinon, trichlorfon, paraoxon, potasan, dimefox, mipafox, schradan, sevin, and dimetonor) in chemical warfare (nerve gases such as tabun and sarin) and are applied as aerosols or dusts. [More…]
Anticholinergic or antimuscarinic medications such as atropine, scopolamine, and glycopyrrolate are competitive antagonists of acetylcholine. Cardiovascular side effects of anticholinergic agents includes tachycardia by blockade of muscarinic receptors in the sinoatrial node. [More…]
Antibiotics, particularly penicillins and cephalosporins are a common cause of drug allergy in surgical patients. Allergic reactions occur in 1% to 4% of all β-lactam administrations, but only 0.004% to 0.015% of these reactions result in anaphylaxis. As great as 2% of the population is allergic to penicillin. [More…]
Tumors (thymoma, teratoma, thyroid CA, lymphoma, hygroma, cyst) of the anterior mediastinum cause obstruction of three structures: the tracheobronchial tree, the main PA (and atria) and the SVC. If the patient can tolerate the supine position, a CT scan should be obtained to define the involvement of each structure. [More…]
Occlusion of the anterior cerebral artery is uncommon, representing only 2% of ischemic strokes.Thus, occlusion of the (ACA) will result in leg weakness. [More…]
Neuraxial anesthesia is complicated by ossification of spinal ligaments and reduced intervertebral spaces – caudal anesthesia may be a reasonable alternative. [More…]
The nerve supply of the foot is primarily from the sciatic nerve: 1. The superficial peroneal nerve (L4-S1) is located lateral to the extensor digitorum longus [More…]
Ankle blocks can be performed for some operations involving the foot and toes. Blocks can be performed on three superficial nerves (superficial peroneal, sural, and saphenous) and two deep nerves (deep peroneal and posterior tibial). [More…]
Dr. Emmett Whitaker and OpenAnesthesia Editor Dr. Jina Sinskey discuss spinal anesthesia in neonates and infants.
Rate of uptake is dependent on 1) alveolar ventilation rate 2) partial pressure of gas (concentration effect) 3) breathing system [More…]
In general a right-to-left intracardiac shunt or transpulmonary shunt will slow the rate of inhalational induction of anesthesia. This occurs because of a dilutional effect of shunted blood, which contains no volatile anesthetic, on the arterial anesthetic partial pressure coming from ventilated alveoli. [More…]
Systemic absorption of LA is determined by site of injection, dosage and volume, addition of vasoconstricting additives, and pharmacologic profile of LA. [More…]
Anesthesiology certification requires Bachelor’s degree, 4 year medical degree, 1 year internship, 3 year anesthesiology residency and pass all certifying exams including USMLE’s Steps 1-3, Anesthesiology Basic exam, Anesthesiology Advanced exam, and Anesthesiology Applied exam. [More…]
In addition to abuse of IV agents, including propofol, [Wischmeyer et al], abuse of volatile agents has also been documents [Zacny and Galinkin]. It is estimated that the incidence of substance abuse among physicians is 2.1% annually (or 7.9% over one’s lifetime) [Hughes]. [More…]
In addition to abuse of IV agents, including propofol, [Wischmeyer et al], abuse of volatile agents has also been documents [Zacny and Galinkin]. [More…]
All volatile halogenated agents cause dose-related relaxation of the uterus which may lead to increased blood loss during cesarean section. [More…]
Electroconvulsive therapy (ECT) is a procedure where a generalized epileptic seizure is purposely induced for the treatment of psychiatric disorders (including acute and chronic depression/mania) that are resistant to medical management. [More…]
There are two primary types of drive mechanisms to deliver gas to the patient: bellows and piston. [More…]
Anesthesia machines have high, intermediate, and low pressure circuits. These are regulated by safety devices built within the machine to ensure optimal delivery to the patient. [More…]
If intraoperative wheezing should develop, nonbronchospastic causes of wheezing (mechanical obstruction of the endotracheal tube, endo- bronchial intubation, pulmonary aspiration, pulmonary embolism, pulmonary oedema, tension pneumothorax, and negative pressure inspiration) must be ruled out. [More…]
According to Miller, pharmacologic agents with the potential to increase intraocular pressure include succinylcholine, ketamine, and nitrous oxide. [More…]
• Reduced hemoglobin concentration with anemia decreases the ability of blood to deliver oxygen. The body uses several compensatory mechanisms to mitigate the impact of this. [More…]
When anemia develops chronically, over a prolonged period of time, and blood volume is maintained, there are four primary mechanisms of compensation. 1. Increased cardiac output [More…]
A shunt refers to blood that bypasses oxygenation in the lungs. There exists a spectrum of shunt from absolute shunt in which the blood receives no oxygen (V/Q=0) to areas that are perfused in excess of their ventilation (0 < V/Q < 1). [More…]
Anemia also affects the coagulation cascade. In a sample of 29 patients with chemotherapy induced anemia, decreased hemoglobin was associated with a delay in the initiation of the coagulation cascade as well as a clot that is both stronger and has superior viscoelastic properties. [More…]
The ACLS dose of epinephrine is 1 mg IV. Similarly, the recommendation for anesthesia providers treating anaphylactic shock in the OR is 0.5 to 1.0 mg. [More…]
Epidemiology: rare (1:20,000 deliveries) but potentially lethal complication (86% mortality rate in some series) [More…]
Mechanism of Action — Unclear (thought to be due to an anti-sympathethic and calcium blocking action) [More…]
Amiodarone is a class III antiarrythmic (potassium channel blocker) although the exact mechanism of action is not completely understood and may involve blockade of multiple channels. [More…]
Description: Amiodarone is an antiarrhythmic used to treat different types of tachyarrhythmias. [More…]
Amiloride is one of the four potassium sparing diuretics (others include spironolactone, eplerenone, and triamterene). [More…]
A K+ sparing diuretic with weak natriuretic and antihypertensive properties inhibits the epithelial Na channel (ENaC) in the late distal convoluted tubule and connecting tubules of the nephron (where 1-2% of total Na reabsorption occurs), effectively inhibiting Na reabsorption at this point. [More…]
October 2020: Dr. Pamela L. Zeitlin and OpenAnesthesia Editor Dr. Debnath Chatterjee discuss the topic of cystic fibrosis.
The type of procedures performed in the ambulatory setting are becoming more diverse and complex. 70% of surgeries performed in the US are now performed in an outpatient setting. The safety and ease of performing anesthetic techniques make this a possibility. [More…]
Risk factors for PONV can be divided into three main categories: patient-related, anesthetic-related, and surgery-related. [More…]
In today’s ambulatory surgery centers, more complex surgical procedures are being safely performed while providing a clear economic benefit in an era of cost containment. The development of improved anesthetics and minimally invasive surgical techniques have made the growth of ambulatory surgery possible. [More…]
The average alveolar diameter is between 0.05 to 0.33 mm, with the largest alveoli at the pulmonary apex and the smallest at the base when in the upright position. [More…]
The alveolar gas equation estimates alveolar oxygen content given a few readily measurable variables. The pAO2 derived from performing the calculation can then be used to discern the degree of shunt present in a patient.[More…]
Alpha receptors Alpha-1 Predominantly expressed on vascular smooth muscle. Agonists cause increase in tone resulting in hypertension (and reflex bradycardia). Think phenylephrine. [More…]
• Released from zona glomerulosa of the adrenal glands • Responsible for long term control (days) of blood pressure and plasma osmolarity [More…]
An aldosterone antagonist is any of a number of diuretic drugs that antagonizes the effects of aldosterone at mineralocorticoid receptors. Examples include drugs such as spironolactone, epleronone, canrenone and finerenone. [More…]
Aldosterone is created from cholesterol within the zona glomerulosa of the adrenal glands. It is controlled by the renin-angiotensin-aldosterone system, while the rest of the adrenal glands hormone production is controlled by adrenocorticotropic (ACTH) hormone. [More…]
Albuterol is a beta-2 adrenergic receptor agonist used to treat reactive airway disease and bronchospasm. The beta-2 receptor is the dominant receptor in the bronchial smooth muscle. [More…]
5% albumin is prepared from human venous plasma and the sodium content is 145 ± 15 mEq/L with the usual concentration being 154 mEq/L. This is roughly the same sodium concentration as normal saline secondary to the albumin being mixed with normal saline. [More…]
Resistance in an airway is equal to change in pressure divided by flow rate [Resistance = (Peak Pressure – Plateau Pressure) / Flow L/sec]. Integrating this equation with Poiseuille’s law, which assumes Laminar flow, it can be shown that resistance is directly proportional to viscosity and length and indirectly proportional to radius. [More…]
The larynx is composed of nine cartilages, three paired and three unpaired and these cartilages contain within them the vocal cords. The movements of the larynx are controlled by the extrinsic muscles which move the larynx as a whole and the intrinsic muscles which move the various cartilages in relation to one another. [More…]
According to the ASA Practice Advisory for the Prevention and Management of OR Fires from 2013, for high-risk procedures (i.e. proximity of an ignition source to an oxidizer-enriched atmosphere), anesthesiologists should collaborate with the procedure team for the purpose of preventing (and managing) a fire … [More…]
Background There are an estimated 50-200 operating room fires annually in the United States including airway and non-airway fires. [More…]
The most common patient injuries related to the administration of anesthesia occur due to the failure to recognize a difficult airway. Whereas many tests exist to predict a potentially difficult airway, the sensitivity and positive predictive values of these tests are poor, even in combination. [More…]
The airway exam is an important part of the pre-operative exam as it allows for appropriate planning and acquisition of necessary resources for airway management. There are several components of the airway exam as below. [More…]
Functional residual capacity equals end-expiratory lung volume in normal patients. Air trapping develops when air remains in alveolae at the end of expiration. In this case, alveolar pressure remains positive, a condition known as intrinsic PEEP or auto-PEEP. [More…]
Treatment of air embolism includes discontinuation of nitrous oxide, aspiration through a right heart catheter, adequate supplementation of inspired oxygen, and prevention of further air entry into the circulation (flooding the field with saline, jugular compression and lowering the head in neurosurgical cases). [More…]
An air embolism can be deteced many different ways. Doppler ultrasound: most sensitive noninvasive monitor capable of detecting 0.05ml/kg of air. Transesophageal echo (TEE): most sensitive invasive monitor can detect as little as 0.02ml/kg of air. [More…]
Age-Related Changes Elasticity is decreased in lung tissues causing Over distention of alveoli- Decreases alveolar surface area and decreases gas exchange efficiency. Collapse of smaller airways resulting in increased residual volume and closing capacity. [More…]
All organ systems undergo physiologic changes with aging. From a cardiovascular standpoint, elderly patients have prolonged myocardial contraction and relaxation times (diastolic dysfunction), decreased arterial elasticity and compliance (increased SVR and PVR), decreased maximal heart rate, and decreased alpha1 and beta-adrenergic responsiveness (reduced chronotropic, inotropic, and baroreflex responsiveness) due to changes in autonomic function. [More…]
It is important to distinguish between changes in physiology that normally accompany aging and the pathophysiology of diseases common in the geriatric population. For example, atherosclerosis is pathological: it is not present in healthy elderly patients. [More…]
Structural changes: Loss of neural tissue Thickened leptomeninges in spinal cord [More…]
Oxygen travels in the blood as a soluble gas or bound to hemoglobin. This is most clearly demonstrated with the equation for O2 content: (1.34 x Hgb x SaO2) + (Pa02 x 0.003) [More…]
Atrial fibrillation (AF) is the most common disorder of the cardiac rhythm and confers an increased risk of stroke that is dependent on the presence or absence of various risk factors. The presence of AF increases the risk of stroke five-fold and contributes to at least 15% of all strokes. [More…]
Virtually all tissues have a requirement for glucose to function normally. Glycolysis is the major pathway of glucose metabolism and occurs in the cytosol of all cells. It can occur aerobically or anaerobically depending on whether oxygen is available. [More…]
According to Miller, “It has been speculated that general anesthesia and surgery may increase the risk for aggravation of MS. [More…]
Primary adrenal insufficiency (Addison’s disease) is defined by failure of adrenal glands to provide sufficient quantities of glucocorticoid, mineralocorticoid, and androgen hormones. It is most commonly caused by bilateral adrenal destruction from autoimmune disease. [More…]
The saphenous nerve traverses the adductor canal. This nerve carries superficial sensation of the medial leg to the ankle and foot. [More…]
Addison’s disease (a primary adrenal insufficiency ) is the loss or degradation of the adrenal cortex resulting in glucocorticoid and mineralocorticoid deficiency. [More…]
Addison’s disease, or primary adrenal insufficiency, is distinguished from other types of adrenal insufficiency in that the primary problem comes from the inability of the adrenal glands to produce sufficient levels of cortisol, and at times, aldosterone. [More…]
Addiction risk factors include : Easy access to potent drugs, particularly opioids [More…]
A behavioral syndrome characterized by evidence of psychological dependence (craving), uncontrolled/compulsive drug use despite harmful side effects, and other drug-related aberrant behavior (e.g., altering prescriptions, manipulating health care providers, drug hoarding or sales, unsanctioned dose escalation). [More…]
Acute tubular necrosis (ATN) is a common diagnosis in acute renal failure, which is a rapidly progressing azotemia (increase in BUN/creatinine) that is often reversible. In order to effectively diagnose ATN, understanding the causes is helpful. [More…]
Septic shock is the final pathway of disseminated infection, and after respiratory failure, is the most common cause of admission to the ICU. The diagnosis of septic shock is based on identifying the probable source of infection, the systemic inflammatory response to infection and concomitant organ failure. [More…]
Acute mountain sickness (AMS) is diagnosed clinically in a person who lives at low altitude but has recently ascended to high altitude (generally over 2000 M). [More…]
Neurological manifestations of both acute and chronic liver disease include hepatic encephalopathy, cerebral edema and seizures. Often, more than one of these is present as their pathophysiology is interrelated. [More…]
Attacks are episodic and typically triggered by inciting factors such as medications, drastic diets/fasting, or stress such as an infection or surgery. [More…]
Em = resting membrane potential of the cell, -90 mV. Maintained by the Na-K ATPase, which pumps K+ INTO the cell and Na+ OUT, as well as the Na-Ca exchanger, which pumps calcium OUT of the cell. [More…]
• Mandible: Macrognathia • Connective tissue: Recurrent laryngeal nerve paralysis caused by stretching of tissues as cartilaginous structures in the neck expand, leading to abnormal VC movement. [More…]
Non-Anion Gap Metabolic Acidosis – USED CRAP U reteroenterostomy/Ureterosigmoid connection- either because of surgical ureteral sigmoidostomy or a ureterosigmoid fistula as may occur in Crohn’s disease [More…]
The “Strong Ion Difference” (SID) is defined as the difference between the completely dissociated cations (e.g. Na+, K+, Ca2+, and Mg2+) and anions (Cl-, lactate-) in plasma. As not all strong ions can be measured, the apparent SID (SIDa) is defined as the difference between the sum of the measured strong cations and the sum […]
Acetylcholine is synthesized from choline and acetyl coenzyme A, catalyzed by the enzyme O-acetyl transferase. Once synthesized, the acetylcholine molecules are stored in synaptic vesicles in high concentration near the motor endplate. [More…]
The acetylcholine receptor (AChR) is a membrane protein that binds to the neurotransmitter acetylcholine (Ach). These receptors can be divided into two main types of distinct receptors, nicotinic and muscarinic. [More…]
Acetazolamide is a reversible inhibitor of the carbonic anhydrase enzyme that results in reduction of hydrogen ion secretion at the renal tubule and an increased renal excretion of sodium, potassium, bicarbonate, and water. [More…]
Acetazolamide is a potent inhibitor of carbonic anhydrase, which results in wasting of sodium and bicarbonate in the proximal tubule, which results diuresis and also alkalinizes the urine. [More…]
Acetazolamide is a carbonic anhydrase inhibitor that results in a metabolic acidosis. Metabolic acidosis triggers an increased respiratory drive with decreased pCO2 in order to compensate for decreased in [HCO3-]. [More…]
Effective analgesic and antipyretic with minimal anti-inflammatory properties. Two theories are proposed for its poor anti-inflammatory action – first, it is thought to be predominantly active in the brain , and second, it appears to be unable to inhibit COX in the presence of peroxides , which are abundant at sites of inflammation. [More…]
Catecholamine surges are thought to be pathogenic in stress (takotsubo) cardiomyopathy (1). This catecholamine induced injury causes ventricular ballooning, dysfunction, and in some cases dysrhythmia and sudden death. [More…]
Patient Population: Occurs predominately in patients in profound shock, in patients requiring large amounts of vasopressors, resuscitation fluids and blood (more than 6 L of crystalloid or 6 units of packed red blood cells over a 6-hour period – Ref 1), in patients who require abdominal packing for abbreviated/staged laparotomy, and in those with major […]
Laparoscopic surgeries are usually performed over open surgeries because laparoscopic procedures are less invasive, which allows for early recovery and return to normal activities. [More…]
Abdominal compartment syndrome (ACS) is defined as a sustained intra-abdominal pressure (IAP) > 20 mmHg that is associated with new organ dysfunction. [More…]
AVMs are abnormal collections of blood vessels with direct arterial to venous connections and no normal intervening capillary circulation. They are typically high-flow, low-resistance. They are believed to be congenital and commonly present in adulthood as hemorrhage or new-onset seizures. [More…]
Thrombolytics: There is insufficient data to support specific recommendations regarding a safe time period for neuraxial puncture to take place after receiving thrombolytics. [More…]
ASRA’s recommendation for herbal supplementation is graded as a 1C (strong recommendations; some key evidence supporting the recommendation is of low quality). [More…]
The Standards for Monitoring is a list of Standards developed by the ASA’s committee on Standards and Practice Parameters for what level of monitoring is required for basic anesthesia care. [More…]
Except as noted, guidelines apply to both moderate and deep sedation. 1. Preprocedure evaluation Relevant history (major organ systems, sedation–anesthesia history, medications, allergies, last oral intake). [More…]
ASA 1 : No organic pathology or patients in whom the pathological process is localized and does not cause any systemic disturbance or abnormality. [More…]
In the continuum of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), the lungs are damaged following an insult that may be of pulmonary (e.g., pneumonia, aspiration pneumonitis) or extrapulmonary (e.g., sepsis, trauma, transfusion) origin. Regardless of the source of injury, ARDS is characterized by an acute onset, bilateral airspace infiltrates on chest […]
According to Miller, “Prone positioning is fraught with difficulty” and can result in accidental extubation, dislodgement of the line or chest tube, and patient injury, “but it can lead to higher functional residual capacity, better drainage of secretions, and improved oxygenation.” [More…]
Amyotrophic lateral sclerosis (ALS) is a degenerative disease process that produces both upper and lower motor neuron degeneration. It most commonly affects men 40 to 60 years of age. Frequent initial manifestations include skeletal muscle atrophy, weakness, and fasciculations. [More…]
Amyotrophic lateral sclerosis (ALS) is a degenerative disease process that produces both upper and lower motor neuron degeneration. It most commonly affects men 40 to 60 years of age. Frequent initial manifestations include skeletal muscle atrophy, weakness, and fasciculations. [More…]
The American Recovery and Reinvestment Act of 2009 (ARRA) provides reimbursement of funds spent to adopt Electronic Medical Records (EMR) that achieve meaningful use. [More…]
The 2010 American Heart Association (AHA) Guidelines for CPR and Emergency Cardiovascular Care (ECC) listed 15 topic areas which require treatments outside the standard BLS and ACLS guidelines. In 2015, these guidelines were updated with 5 new or updated topic areas. [More…]
Absolute Contraindications Angioneurotic edema: even if not due to ACE Inhibitor [More…]
ACE inhibitors are a commonly used antihypertensive medication, especially in patients with concomitant heart failure (to reduce maladaptive remodeling). [More…]
As of May 2015, 123,331 people waiting for life-saving organ transplants in the U.S. Of these, almost 100,000 await kidney transplants. [More…]
Dr. Jina Sinskey and OpenAnesthesia Editor Dr. Alyssa Burgart discuss topic of bioethics.
Aldosterone is created from cholesterol within the zona glomerulosa of the adrenal glands. It is controlled by the renin-angiotensin-aldosterone system, while the rest of the adrenal glands hormone production is controlled by adrenocorticotropic (ACTH) hormone. [More…] See all 2020 Keywords here!
The average alveolar diameter is between 0.05 to 0.33 mm, with the largest alveoli at the pulmonary apex and the smallest at the base when in the upright position. [More…] See all 2020 Keywords here!
Anticholinergic or antimuscarinic medications such as atropine, scopolamine, and glycopyrrolate are competitive antagonists of acetylcholine. [More…] See all 2020 Keywords here!
The Blood Gas Partition Coefficient is also known as Ostwald coefficient for blood–gas. A partition coefficient is the ratio of the concentrations of a compound in one solvent to the concentration in another solvent at equilibrium. [More…] See all 2020 Keywords here!
Anesthesiology certification requires Bachelor’s degree, 4 year medical degree, 1 year internship, 3 year anesthesiology residency and pass all certifying exams including USMLE’s Steps 1-3, Anesthesiology Basic exam, Anesthesiology Advanced exam, and Anesthesiology Applied exam. [More…] See all 2020 Keywords here!
Ancillary tests, such as Transcranial Doppler, Cerebral Angiography, CTA, MRA, Nuclear Med, Somatosensory Evoked Potentials and EEG, are available if confounding factors are present and in some countries they are required in addition to the clinical exam. [More…] See all 2020 Keywords here!
Elderly patients have an increased incidence of heart failure and cardiomyopathy. This is in part due to the increased incidence of ischemic coronary artery disease, hypertension, and diabetes leading to cardiomyopathy. [More…] See all 2020 Keywords here!
The principle ions involved in the cardiac cycle are sodium, potassium, and calcium. There are two different clinically significant forms of cardiac action potentials and resulting ion movement: 1.) SA node and 2.) Atria, ventricles, and Purkinje system. [More…] See all 2020 Keywords here!
Developed by Adolf Fick, the Fick Principle can determine cardiac output if an investigator knows what amount of a substance is taken up by an organ (or whole body) in a unit of time, the concentration of the substance in the arterial blood supplying the organ (or whole body), and the concentration of the venous […]
Blood temperature is typically measured either by a thermistor on the end of a PA catheter, or by the bypass machine itself. This temperature is the quickest to change, as heat is added or removed by the perfusionist directly to the blood. [More…] See all 2020 Keywords here!
The majority of direct acting vasodilating agents (i.e. hydralazine, sodium nitroprusside, nitroglycerin, and calcium channel blockers) cause an increase in cerebral blood volume. [More…] See all 2020 Keywords here!
Cerebral Palsy represents a large spectrum of symptoms usually stemming from an injury to the developing brain which impairs various neurological functions and has wide ranging sequelae across many organ systems (e.g. mild monoplegia to spastic quadriplegia; normal cognition to severe MR). [More…] See all 2020 Keywords here!
After coronary artery stenting, patients are maintained on dual antiplatelet therapy (DAPT). When presenting for elective surgery, these medications are often held to minimize bleeding risk intraoperatively. [More…] See all 2020 Keywords here!
Pharmacokinetics is the study of how a drug is affected by the body (i.e. Absorption, distribution, metabolism, and excretion). Differences in genetic make-up alter a patient’s ability to respond to or metabolize a drug. [More…] See all 2020 Keywords here!
Also known as extravascular hemolysis Generally mild and caused by antibodies to non-D antigens of the Rh system or to foreign alleles in other systems such as the Kell, Duffy, or Kidd antigens [More…] See all 2020 Keywords here!
MOA: central alpha-2 adrenergic agonist, acts on receptors in the brain (locus ceruleus) and spinal cord In the same class as clonidine but dexmedetomidine is more selective for alpha 2 receptors [More…] See all 2020 Keywords here!
Rocuronium: Elimination half-time is increased by 37%; however, due to increased volume of distribution and plasma clearance in CRF, the duration of action is not significantly prolonged. [More…] See all 2020 Keywords here!
Vasoconstrictors, such as epinephrine, can be added to local anesthetics. The addition of epinephrine causes multiple effects. [More…] See all 2020 Keywords here!
Relevant Anatomy Femoral nerve (posterior divisions of L2-4) is formed in the psoas major muscle, runs between psoas and iliacus muscles and enters the thigh under the inguinal ligament lateral to the femoral artery, at which point it divides into multiple terminal branches (usually classified as anterior [mostly cutaneous] and posterior [mostly motor]) [More…] See […]
MOA: central alpha-2 adrenergic agonist, acts on receptors in the brain (locus ceruleus) and spinal cord In the same class as clonidine but dexmedetomidine is more selective for alpha 2 receptors [More…] See all 2020 Keywords here!
Rocuronium: Elimination half-time is increased by 37%; however, due to increased volume of distribution and plasma clearance in CRF, the duration of action is not significantly prolonged. [More…] See all 2020 Keywords here!
Originally introduced for colorectal surgery and subsequently expanded to include other surgical specialties, Enhanced Recovery After Surgery (ERAS) protocols aim to reduce hospital length of stay, cost, and complication rates while increasing patient comfort and satisfaction. [More…] See all 2020 Keywords here!
Vasoconstrictors, such as epinephrine, can be added to local anesthetics. The addition of epinephrine causes multiple effects. [More…] See all 2020 Keywords here!
July 2020: Dr. Kirk Lalwani and OpenAnesthesia Editor Dr. Debnath Chatterjee discuss an update on the SPA.
Anatomy Place the patient supine with head turned to the opposite side to be blocked. [More…] See all 2020 Keywords here!
When placing an internal jugular central line it is essential to confirm intravenous placement of the line. Inadvertent intra-arterial placement can lead to hematoma, stroke, airway compromise and death. [More…] See all 2020 Keywords here!
The ability of the colloid solutions to remain intravascular is due to the oncotic pressure that large molecules, such as albumin, exert. [More…] See all 2020 Keywords here!
Ketamine dissociates the limbic system and cortex from sensory impulses by antagonizing the NMDA receptor from glutamate. [More…] See all 2020 Keywords here!
Local Anesthetic Toxicity (LAST) is a relatively rare complication that results from elevated plasma concentrations of local anesthetics most often after accidental intravascular injection. [More…] See all 2020 Keywords here!
All physicians need a full unrestricted medical license to practice clinical medicine within the US. Medical licensing is controlled by individual states, and the licensing board and statutes can vary from state to state.[More…] See all 2020 Keywords here!
A meta-analysis by Knackstedt et al. in 2019 examined vasopressor usage and risk of complications in microvascular surgery for all recipient sites. [More…] See all 2020 Keywords here!
In healthy patients, renal function is not dependent on prostaglandin formation for optimal function. In patients with pathophysiology such as CHF, hepatic cirrhosis, CKD, or hypovolemia, however, renal function becomes more dependent on the effects of prostaglandin for optimal functioning. [More…] See all 2020 Keywords here!
Hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) are the three bloodborne infectious organisms which pose the greatest percutaneous exposure risk to the anesthesiologist. [More…] See all 2020 Keywords here!
Spinal selectivity: liposolubility is inversely proportional to their spinal selectivity, which is higher for the most water-soluble drug, morphine, than for other more lipophilic drugs, such as fentanyl and sufentanil Lipophilic drugs (Fentanyl) diffuse intravascularly quickly and then reach brainstem via systemic circulation. [More…] See all 2020 Keywords here!
Regulation of office based anesthesia is delegated to individual states. Lack of federal guidance and with few states having published guidelines, the ASA has published Guidelines for Office-Based Anesthesia first adopted in 1994 but most recently amended in Oct. 2018. [More…] See all 2020 Keywords here!
Omphalocele describes the herniation of abdominal viscera into the umbilical cord through a central defect at the base of the cord. [More…] See all 2020 Keywords here!
Standard ASA monitoring – including SpO2, HR, NIBP, temperature, capnography. [More…] See all 2020 Keywords here!
Venous capacitance is increased in pregnancy and myocardial remodeling occurs. The heart is displaced laterally and cephalad which can result in left axis deviation on ECG. Other common ECG findings include sinus tachycardia, LVH, ST depressions and T-wave flattening. [More…] See all 2020 Keywords here!
All drugs cross the placenta to some degree but several factors determine the degree of placental transfer. Major determinants include lipid/water solubility, molecular weight, degree of ionization, and protein binding. [More…] See all 2020 Keywords here!
Fetal supply of blood is facilitated by three factors: Oxygen concentration and partial pressure gradient within the feto-maternal circulatory system Fetal hemoglobin (HbF), which has higher affinity (lower P50 of 19mmHg) for oxygen then adult hemoglobin (HbA) with a P50 of 26.8mmHg. This facilitates transfer oxygen transfer from mother to fetus. Bohr effect [More…] See […]
Postoperative visual loss after non-ocular procedures is a rare but devastating complication after general anesthesia. [More…] See all 2020 Keywords here!
Inulin clearance is the gold standard for measuring GFR. [More…] See all 2020 Keywords here!
Retrobulbar blocks are known to cause a variety of complications including: Retrobulbar hemorrhage – this can lead to central retinal artery occlusion which can result in vision loss if not properly treated. [More…] See all 2020 Keywords here!
The Apnea Hypopnea Index (AHI) stratifies the severity of sleep apnea. [More…] See all 2020 Keywords here!
The term “interval” is used to describe data that is ordered in a way that specifies that the distance between each interval on the scale are equivalent along the scale. [More…] See all 2020 Keywords here!
TCAs have diverse mechanisms of action which accounts for the wide array of symptoms that can present in an overdose situation. [More…] See all 2020 Keywords here!
Tramadol is a centrally acting synthetic opioid medication with monoaminergic actions similar to serotonin norepinephrine reuptake inhibitors (SNRIs). [More…] See all 2020 Keywords here!
Gas Laws: temperature/pressure changes
PV=NRT
where k is the Boltzmann constant [More…]
The 2020 Keywords are here!
ED95 (mg/kg) of Commonly used NMBDs (Adapted from Table 29-4 in Miller) [More…] The 2020 Keywords are here!
Aldrete’s original scoring system has been modified, but originally required a score of 9 or greater to leave the PACU (i.e. you could only miss one point on the following scale) [More…] The 2020 Keywords are here!
A decrease in prostaglandin E2 (PGE2), along with exposure to oxygenated blood, causes the ductus arteriosus to close after birth. [More…] The 2020 Keywords are here!
All organ systems undergo physiologic changes with aging. From a cardiovascular standpoint, elderly patients have prolonged myocardial contraction and relaxation times (diastolic dysfunction), decreased arterial elasticity and compliance … [More] The 2020 Keywords are here!
Anesthesia machines have high, intermediate, and low pressure circuits. These are regulated by safety devices built within the machine to ensure optimal delivery to the patient. [More…] The 2020 Keywords are here!
Nitric Oxide is a colorless, odorless gas that is relatively insoluble in water and is found in naturally atmosphere at concentration range of 10-500 ppb. [More...] The 2020 Keywords are here!
Succinylcholine dosing for optimal intubating conditions should be based on total body weight. Onset of complete neuromuscular blockade largely remains similar despite variability in dosing. [More…]
Goals of Ventricular Function Monitoring In concentrating on TEE’s role in assessing acute coronary ischemia and since active ischemia can be seen on a TEE much earlier than any changes in EKG, interpretation of any wall motion abnormalities and how they correlate to coronary artery distribution can be crucial to intraoperative management for an anesthesiologist. […]
The transmural pressure of an aneurysm is related to the difference between the Mean Arterial Pressure (MAP) and Intracranial Pressure (ICP): Transmural Pressure= CPP= MAP – ICP [More…]
Nerve agents typically refer to a subgroup of drugs in the class of organophosphates (OP). Among these are Tabun (GA), Sarin (GB), Soman (GD, isopropyl methyl phosphonofluoridate), Cyclosarin (GF), VX, and VR. [More…]
Respiratory quotient is the ratio of VCO2 and VO2: RQ = CO2 eliminated/O2 consumed [More…]
Hyperbaric oxygen therapy (HBO) is an adjunctive therapy used to treat a number of specific conditions, including acute venous or arterial gas embolism (to reduce the gas bubble size), severe carbon monoxide or cyanide poisoning, to improve wound healing (non-healing ulcers, skin grafts, etc), decompression sickness, and acute traumatic or ischemic injuries (crush, compartment syndrome, […]
Stellate ganglion block (also called a cervicothoracic sympathetic block) is used primarily to treat Complex Regional Pain Syndrome, but has also been used to treat refractory angina, phantom limb pain and vascular insufficiency (such as Raynaud’s or frostbite),hyperhydrosis and other things. [More…]
As of May 2015, 123,331 people waiting for life-saving organ transplants in the U.S. Of these, almost 100,000 await kidney transplants. [More…]
Alkalemia is the condition of having a higher blood pH. Metabolic alkalosis is the condition of having elevated bicarbonate in the setting of alkalemia; or, an increased strong ion difference (the difference between positively-charged strong ions and negatively-charged strong ions). [More…]
Strong ions are cations and anions that exist as charged particles dissociated from their partner ions at physiologic pH. Thus, these ions are “strong” because their ionization state is independent of pH. [More…]
Hypercapnia, or high PaCO2, can occur in numerous scenarios during anesthetic and post-anesthetic care. In the operating room, hypercapnia is typically detected with capnography.; however, this monitor is not always available outside of the operative environment. [More…]
This keyword refers to the phenomenon of distal pulse amplification. When blood pressure is measured arterially from multiple sites simultaneously, the morphology of the signal changes dependent upon changing characteristics of the vascular tree. [More…]
Prevention of central venous catheter (CVC) infections has become an important patient safety and quality improvement measure over the last decade. In 2011, the CDC amended their guidelines to provide the most up to date, evidence-based practice recommendations for preventing catheter related infections. [More…]
The immediate physiologic response to drowning is breath-holding. After breath-holding, involuntary laryngospasm can occur with entry of fluid into the oropharynx and larynx. [More…]
The National Practitioner Database (NPDB) is an electronic repository of all payments made on behalf of physicians in connection with medical liability settlements or judgments as well as adverse peer review actions against licenses, clinical privileges, and professional society memberships of physicians and other health care practitioners. [More…]
Hypoxic pulmonary vasoconstriction (HPV) is a physiologic mechanism by which lung perfusion is adjusted to match ventilation through the contraction of vascular smooth muscle in the pulmonary circulation in response to low regional partial pressure of oxygen. [More…]
The lung is particularly suited to function as a “chemical filter” as it receives 100% of cardiac output and has the largest capillary endothelial surface in the body. [More…]
Adverse cardiovascular effects of PEEP can include progressive reductions in cardiac output as mean airway pressure and, secondarily, mean intrathoracic pressure rise. [More…]
Increasing partial pressure of oxygen in the blood (hyperoxia) leads to increased reactive oxygen intermediates (ROI) – superoxide anion, hydroxyl radical, and hydrogen peroxide. [More…]
For a volatile anesthetic agent, the time constant (τ) is volume divided by flow. From the standpoint of the anesthesia circuit, the time constant is the volume of the circuit divided by the fresh gas flow rate (units of L divided by L/min results in min). [More…]
During hypothermia, pH-stat (reporting of blood gases at body temperature) corrects for the effects of temperature on pH in order to keep the pH static (7.4). This often results in the addition of CO2 to the CPB circuit. [More…]
Mapelson systems are classified based on the location of the fresh gas flow inflow and overflow valves relative to the patient connection. They all share the benefit of decreased resistance due to the absence of unidirectional valves and canisters. [More…]
Imaging the aortic valve is best accomplished in the mid-esophageal short and long axis views. The ME AV SAX demonstrates the noncoronary cusp superiorly, the right coronary cusp inferiorly, and the left coronary cusp to the right. [More…]
Innervation of the Abdominal Wall The anterior rami of spinal nerves T7-L1 innervate the anterolateral abdominal wall. [More…]
Normal muscle releases enough potassium during succinylcholine-induced depolarization to raise serum potassium by ~ 0.5 mEq/L. [More…]
Succinylcholine’s interaction with nicotinic receptors in the muscle leads to depolarization of skeletal muscle cells that, in turn, causes an efflux of intracellular potassium. [More…]
Strong ions are cations and anions that exist as charged particles dissociated from their partner ions at physiologic pH. Thus, these ions are “strong” because their ionization state is independent of pH. [More…]
- Infectious a. Croup (laryngotracheobronchitis)- most commonly caused by parainfluenza virus as well as influenza and RSV. Inflammation and swelling occurs below the level of the vocal chords. Croup presents as barking cough and breathing difficulty. Subglottic narrowing (steeple sign) is classically on chest x-ray. [More…]
Trendelenburg positioning is often used during abdominal and pelvic operations in order to optimize exposure, as well as during central line placement in order to facilitate cannulation while avoiding air embolism, and during episodes of hypotension in order to increase venous return. [More…]
Most important factors: Baricity of anesthetic solution (relative to CSF) Hyperbaric (glucose added) – follows gravity, greater cephalad spread, normal dependent portion of spine in supine position is T4-T8 [More…]
According to Miller, Figure 59-52, the paramedian approach to the epidural space is now favored by most anesthesiologists at the midthoracic levels. The needle is inserted 1 cm lateral to the superior tip of the spinous process and then advanced perpendicular to all planes to contact the lamina of the vertebral body immediately below. [More…]
The spinal cord receives blood supply from two posterior arteries (25%) and one anterior spinal artery (75%). The posterior arteries supply the sensory tracts in the spinal cord and receive flow from posterior and inferior cerebellar arteries, the vertebral arteries, and the posterior radicular arteries. [More…]
Disease states involving upper motor neuron lesions can cause spasticity and chronic pain. Posturing, muscle spasms, contractures, and loss of mobility all contribute to pain. [More…]
Sodium nitroprusside is a medication that is used to lower blood pressure via continuous infusion. Nitroprusside is metabolized into nitric oxide, which acts as both a potent arteriolar and venous dilator. [More…]
Smoking is a major risk factor associated with perioperative respiratory and cardiovascular complications. Evidence also suggests that cigarette smoking causes imbalance in the prostaglandins and promotes vasoconstriction and excessive platelet aggregation. [More…]
In the first 48-72 hours quitters may have increased secretions and more reactive airways. Acute cessation decreases carboxyhemoglobin and increases oxygenation to tissues (right shift of oxyhemoglobin curve), less carbon monoxide, less nicotine and associated tachycardia, and increased ciliary function. [More…]
The effects of carbon monoxide on oxygen-carrying capacity are short-lived. The elimination half-life of CO is approximately 4-6 hours when breathing room air. The p50 of oxygen increases from 22.9 to 26.4 mm Hg after only 12 hours of smoking cessation. [More…]
Transducer characteristics, such as frequency and shape, determine ultrasound image quality. Ultrasound waves have frequencies that exceed the upper limit for audible human hearing, i.e., greater than 20 kHz. Medical ultrasound devices use sound waves in the range of 1–20 MHz. [More…]
Formally speaking, “Shock is defined as a state of cellular and tissue hypoxia due to reduced oxygen delivery and/or increased oxygen consumption or inadequate oxygen utilization” (Gaieski). [More…]
Septic shock is a hypermetabolic state in which the body responds to the infection with an amplified immune response, which results in fevers and increased protein production. [More…]
Septic shock is typically defined by the combination of sepsis (SIRS criteria with evidence of infectious source) with severe hypotension despite resuscitation. [More…]
Secondary hypothyroidism results from a failure at some point of the hypothalamic-pituitary axis and not as a result of dysfunction in the thyroid itself. In the normal pathway, the hypothalamus secretes TRF (thyrotropin-releasing factor) and TRH (thyrotropin releasing hormone), which prompt the anterior pituitary to produce TSH (thyroid-stimulating hormone). [More…]
Rhabdomyolysis is a syndrome involving widespread muscle breakdown and necrosis following muscle injury with subsequent release of K+, CPK, myoglobin… [More]
April 1, 2020 Hemoglobin structure and function Oxygen-Hemoglobin binding Oxygen-Hemoglobin Dissociation Curve Factors influencing left and rightward shift
Cardioplegia can be delivered using several routes: • Through the aortic root after cross clamping anterograde down the coronary arteries [More…]
Surgery involving the cornea, anterior chamber, and lens can be performed with a retrobulbar or peribulbar block. [More…]
A retrobulbar block is frequently used for various ophthalmologic procedures including surgeries of the cornea, anterior chamber, and lens. [More…]
Administration of 100% FiO2 prior to intubation to extend the “safe apnea time” (until SaO2 drops to ~88-90%) via denitrogenation of the lungs, which results in a large alveolar oxygen reservoir [More…]
Minute ventilation is determined by the product of tidal volume and respiratory rate. However, only a portion of what is inspired participates in gas exchange at the level of the alveoli and respiratory bronchioles and the rest remains as dead space. [More…]
Nerve damage tends to occur via two main mechanisms: pharmacologic toxicity and needle trauma. Both are uncommon and usually self-limited in nature. [More…]
Occupational exposure to radiation can have many consequences, the most common being lens opacities and cataracts. The latency period between irradiation and cataract formation is inversely proportional to dose, and can range from years to decades. [More…]
Congenital Long QT Syndrome: Due to ion channel abnormalities in LQT1 and LQT2 (potassium channels) and LQT3 (sodium channels) that affect cardiac replorization. [More…]
Ventilator Associated Pneumonia (VAP) is one of the most common acquired infections ICUs. Rates of VAP range from 1 to 10 cases per 1,000 ventilator‐days. VAP mortality may exceed 10%. [More…]
In order to reduce the risk of complications from prolonged mechanical ventilation, patients should be weaned from mechanical ventilation as soon as it is clinically appropriate to do so. [More…]
Cardiac output increases throughout gestation, about 35-40% during the first trimester and then to 50% above baseline during the second and third trimesters. [More…]
During pregnancy, the parturient develops a degree of hypercoagulability, likely as a protective mechanism for delivery of the fetus. Most procoagulants are increased such as 2, 7, 9, 10 but especially fibrinogen or factor 1. [More…]
According to Niederman, “The entity of aspiration pneumonia in pregnant patients is a familiar one: in the 1960s as many as 2% of all maternal deaths were the result of aspiration.” [More…]
Preeclampsia – presence of hypertension (sustained SBP ≥140 mmHg or DBP ≥90 mmHg while sitting) and proteinuria after the 20th week of gestation, present in 6-8% of pregnancies. [More…]
Hypokalemia: Earliest change →ST-segment depression, T-wave flattening and inversion, PR interval prolongation along with increase in P-wave amplitude. [More…]
Sepsis is an infection-induced syndrome defined as the presence of two or more manifestations of a systemic inflammatory response syndrome (SIRS). SIRS includes: [More…]
Postoperative jaundice is defined as the elevation of bilirubin that occurs after the completion of surgery and has many possible causes, associated laboratory findings, and implications. It can, but not always, be associated with icterus. [More…]
Herpes zoster is caused by the varicella zoster virus which lies dormant in dorsal root ganglia and becomes active again during immunosuppression or as immunity declines with advancing age. [More…]
Several risk factors for post-operative cardiac complications after major noncardiac surgery have been identified. Goldman et al. in 1977 published a prospective study of 1001 patients over the age of 40 and identified “nine independent significant correlates of life-threatening and fatal cardiac complications.” [More…]
Porphyrias are a set of autosomally inherited metabolic disorders that are the result various defects in heme synthesis. Broadly, they can be classified into inducible, and non-inducible forms. [More…]
Laparoscopic surgery requires the insufflation of the abdominal cavity for visualization and working space. The most common gas used for insufflation is CO2 because it is colorless, non-flammable, and non-toxic. Insufflation is usually maintained at an intra-abdominal pressure (IAP) between 10-15 mmHg (normal <5mmHg). [More…]
by James Lamberg, DO Case Study: Cardiac Arrest After Intubation Paramedic Unit 44 is dispatched to a nursing home for a patient in severe respiratory distress. You, serving as the medic on that unit, gather your equipment and head into the building with EMT Mukherjee. You are directed into the patient’s room and find an […]
Physiologic changes at altitude are primarily related to the decreased partial pressure of oxygen, rapid respiratory compensation, and slower metabolic compensation. [More…]
In utero fetal circulation is different from adult circulation in 4 primary ways: 1) Umbilical venous blood bypasses the liver by way of the ductus venosus 2) Blood is shunted from right atrium to left atrium through the foramen ovale [More...]
Incidence: 60% Shown to be consistent regardless of country, procedure or health care system Who is at greatest risk? Age > 7 years [More…]
Temperature regulation is important in pediatric patients, particularly neonates, as they are prone to greater heat loss in the operating room when compared to adults. This is because of their larger surface area per kilogram, thinner skin and lower fat content. [More…]
Sedation for pediatric procedures may be requested both inside and outside of the operating room and can range from anxiolysis to general anesthesia. [More…]
Sedation is often requested for pediatric patients outside the OR for nonsurgical procedures such as imaging studies, bronchoscopy, endoscopy, cardiac catheterization as well as minor procedures such as casting and bone marrow aspiration. [More…]
The pediatric airway is different than the adult airway. There are typical characteristics of a pediatric airway that make airway management different than the adult. [More…]
In a nutshell, patient-controlled analgesia (PCA) provides superior postoperative analgesia and improved patient satisfaction compared to traditional PRN analgesic regimens because the person feeling the pain is in control, and they FEEL in control. [More…]
Drowning, as a cause of death, involves impairment of the respiratory system via either immersion (upper airway above water) or submersion (upper airway under water). The pathophysiology of drowning is complex and involves both the salinity and temperature of the submersing liquid. [More…]
The PACU is traditionally divided into phases 1 and 2. Phase 1 has monitoring and staffing ratios equivalent to the ICU. Phase 2 is a transitional period between intensive observation and either the surgical ward or home. [More…]
Pacemakers and intra-cardiac defibrillators share a similar nomenclature which was developed as a way to standardize programming across the world. For both devices, the first letter indicates the chamber(s) paced, the second indicates the chamber(s) sensed, and the third letter indicates the response(s) to sensing. [More…]
The main concern is electromagnetic interference (EMI) from electrocautery (especially monopolar), evoked potential monitors, nerve stimulator, external defibrillation, radiofrequency ablation, and extracorporeal shockwave lithotripsy. EMI can be interpreted as intrinsic cardiac signal. [More…]
Paced chamber [O, A, V, D (A+V)] Sensed chamber [O, A, V, D (A+V)] Response to sensed event [O, Inhibited, Triggered, D (I+T)] [More…]
Organophosphate compounds are used as commercial insecticides (isulfoton, phorate, dimethoate, ciodrin, dichlorvos, dioxathion, ruelene, carbophenothion, supona, TEPP, EPN, HETP, parathion, malathion, ronnel, coumaphos, diazinon, trichlorfon, paraoxon, potasan, dimefox, mipafox, schradan, sevin, and dimetonor) in chemical warfare (nerve gases such as tabun and sarin) and are applied as aerosols or dusts. [More…]
The brain dead donor may produce inadequate amounts of antidiuretic hormone (ADH) from the posterior pituitary resulting in urine volumes of over 1000 mL/hour, resulting in diabetes insipidus. [More…]
As of May 2015, 123,331 people waiting for life-saving organ transplants in the U.S. Of these, almost 100,000 await kidney transplants. Over 100,000 Americans are on the waiting list in need of an organ, yet on average there are only 30,000 transplants performed each year. [More…]
Abdominal wall defects are reported to occur in up to 1 in 2000 births. The two most common are gastroschisis and omphalocele . Omphalocele is an abdominal wall defect occurring in approximately 1 in 5000 births. [More…]
The equianalgesic conversion ratio for IV to epidural to intrathecal opioids varies depending upon the meningeal permeability of the opioid in question. How lipophilic the drug is, as well as in part by its molecular weight, and possibly structure, affect meningeal permeability. [More…]
In general, omphaloceles and gastroschisis are abdominal wall defects noted at birth with exposed viscera, which puts neonates at risk for dehydration due to severe fluid loss, the potential to develop partial bowel obstructions, potential for infections, and heat loss from exposed abdominal compartment. [More…]
There are several factors that have been demonstrated to predict hypoxemia during one-lung ventilation during thoracic surgery. These include: A relatively high percentage of ventilation or perfusion to the operative lung as seen on pre-operative ventilation/perfusion scan [More…]
Oliguria is defined as having a urine output of <0.5mL/kg/hour. While urine output does not always correlate with glomerular filtration rate (GFR) and rarely results in acute kidney injury, it does serve a purpose in identifying the level of kidney injury defined by the RIFLE and AKIN (Acute Kidney Injury Network) criteria. [More…]
The ASA has produced a set of guidelines regarding the delivery of office-based anesthesia and the special considerations this brings. It defines the expected medical leadership roles of the practice and the need for compliance with building standards laid out by state and federal bodies. [More…]
Succinylcholine dosing for optimal intubating conditions should be based on total body weight. Onset of complete neuromuscular blockade largely remains similar despite variability in dosing. Duration of action of neuromuscular blockade is increased with more liberal dosing. [More…]
Obese patients develop respiratory disease in a restrictive pattern, with decreased FEV1 and FVC but preserved FEV1/FVC ratio. Fat collections on the chest wall lead to decreased chest wall compliance and possibly lung compliance as well. [More…]
Pharmacodynamics and pharmacokinetics both change with age: ● Smaller initial volume of distribution and lower muscle mass→ increased initial drug [More…]
Neuropathic pain results from damage to an afferent pathway that can be the result of a disease, trauma, or dysfunction. [More…]
Background: Nerve gas agents were originally used as pesticides and thus are similar to organophosphates. They were later developed by the military for use as chemical weapons. Each agent has a chemical name and a military name(two letters). For example: Soman (GD), methylphosphonothioate (VX), Sarin (BG). [More…]
Weakness and hypotonia in newborns can be caused by disorders of the neuromuscular junction. Transient acquired neonatal myasthenia gravis is characterized by abnormal neuromuscular transmission leading to muscle fatigability and weakness. [More…]
From 2-3 weeks of age, all infants (i.e., full-term and premature) in a warm environment respond to hypoxemia with a transient increase in ventilation followed by sustained ventilatory depression, however in infants born at 32 to 37 weeks, hyperpnea does not occur in a cool environment. [More…]
Hepatitis B prophylaxis Current CDC guidelines call for the administration of hepatitis B immune globulin (HBIG) and/or hepatitis B vaccine. While the efficacy of the combination has not been evaluated in the needlestick injury setting, it has been shown to be the most efficacious approach in the perinatal setting. The approach has no contraindications during […]
Myasthenia Gravis is an autoimmune disorder in which antibodies destroy and/or inactivate acetylcholine receptors, preventing the binding of acetylcholine at the neuromuscular junction leading to progressive weakness with repeated muscle use. [More…]
Ensure that the patient is reminded prior to induction of the possibility of a prolonged intubation. Extubation: performed on awake patients and hopefully close to his/her baseline status. Reinstitute anticholinesterase medication, either by IV infusion or by reimplementation of the patient’s oral regimen.[More…]
Pharmacologic management of myasthenia gravis [1] consists of symptom management with anticholinesterase agents, chronic immunosuppression, and in severe cases, rapid intravenous immunotherapy. [More…]
The requirement for post-op mechanical ventilation in myasthenia gravis patients is based on multiple factors including perioperative risk factors as well as pre-operative health. [More…]
One element of anesthesia care which may be extremely important is temperature management – increases as little as 1 C may lead to disease exacerbation. [More…]
Invasive MRSA is typically treated with vancomycin or daptomycin. Vancomycin is a glycopeptide that inhibits cell wall synthesis. Although this is usually the first choice, there is growing concern regarding emerging resistance to Vancomycin and tissue penetration is limited to bone, lung, and CSF. [More…]
It is generally understood that direct electromagnetic induction in looped cables associated with the patient are responsible for the excessive heating, and it is on this theory that present guidelines are based. [More…]
The American College of Radiology uses a four-zone concept to describe the location of patients and personnel in relation to the MRI scanner to provide safe patient care. The zones are listed below: • Zone I: This region includes all areas that are freely accessible to the general public. [More…]
Patients cannot be seen because they are generally enveloped by the MRI machine (although remote visualization should be employed, if available). EKG is confounded by artifactual T and ST wave changes (from aortic blood flow) as well as artifacts from the magnetic field. [More…]
Absolute Contraindications to MRI include: • Pulmonary artery monitoring catheters and temporary transvenous pacing leads • Intra-aortic balloon pumps • Left and right ventricular assist devices [More…]
An additional step in the preoperative and preprocedural evaluation of a patient undergoing an MRI is the determination of any medical implants that the patient might have. [More…]
The overall respiratory problem is one of restrictive lung disease. Chest wall and lung compliance are decreased from the heavy layer of fat. Subsequent decreased pulmonary compliance leads to decreased FRC (primarily a result of lowered ERV), decreased VC, and decreased TLC. [More…]
The predominant cause of worsened oxygenation in obesity is a reduction in functional residual capacity (FRC) and increased airway closure which essentially produces a right-to-left shunt. High FiO2 can contribute to this pathology by promoting atelectasis and further worsening shunting. [More…]
Associated Cardiovascular Disease • Cor pulmonale secondary to pulmonary hypertension • Left ventricular hypertrophy [More…]
Malignant hyperthermia (MH) is a rare complication of anesthesia that typically presents with the sudden onset of hypermetabolism after general anesthesia has been induced, usually as a result of exposure to inhaled, halogenated anesthetics and/or succinylcholine. [More…]
One-lung ventilation is typically utilized for intrathoracic noncardiac surgery, although it has applications in some cardiac surgical procedures. Many of these procedures are performed in the lateral position with an open hemithorax. The goal of these anesthetics is to maximize atelectasis in the surgical lung to maximize surgical access while at the same time avoiding […]
In medicine, methylmethacrylate is used as bone cement when it is polymerized with other compounds. In orthopedics it is used in certain total hip replacements. Cementless procedures have a longer lifespan; however, they require healthier bone and patients must undergo longer recovery periods. [More…]
Alkalemia is the condition of having a higher blood pH. Metabolic alkalosis is the condition of having elevated bicarbonate in the setting of alkalemia; or, an increased strong ion difference (the difference between positively-charged strong ions and negatively-charged strong ions). [More…]
Anatomic changes: Progressive increase in ligamentous laxity peaks at 37 weeks due to the hormone relaxin, which increases the AP and transverse diameters of the lower rib cage while decreasing the height of the chest cavity due to elevation of the diaphragm. [More…]
Nerve agents typically refer to a subgroup of drugs in the class of organophosphates (OP). Among these are Tabun (GA), Sarin (GB), Soman (GD, isopropyl methyl phosphonofluoridate), Cyclosarin (GF), VX, and VR. [More…]
Anesthesiologists are likely to care for a patient with known MH susceptibility or a patient with a personal or family history of what could potentially have been MH. While definitive knowledge of whether a patient is MH susceptible would be extremely valuable when they present for surgery, testing for MH is not nearly as simple […]
- Immediately discontinue anesthetics, including succinylcholine. Life-threatening surgery will be continued, but with the use of a non-triggering anesthetic agent and machine to prevent residual inhalation agent from triggering a second episode. [More…]
Parenteral magnesium sulfate is commonly used in obstetrics for tocolysis to halt preterm labor, and as an anticonvulsant in pre-eclampsia/eclampsia. Magnesium plays an important role in determining the electrical potential across cell membranes. It is a co-factor in the Na/K ATPase system and is required for the generation of cAMP. [More…]
Factors affecting MAC Significant hypoxia (below 40 mm Hg) decreases MAC. Hypothermia decreases MAC. [More…]
Lung ultrasound is a group of point-of-care bedside exams, which has the following potential applications: (1) diagnosis of pneumothorax; (2) diagnosis of interstitial syndrome; [More…]
Deflation of a lower extremity tourniquet causes multiple physiologic effects based on return of blood from the ischemic limb back into systemic circulation as well as the return of blood flow back into the ischemic limb. [More…]
December 2019: Dr. Nicholas Dalesio and OpenAnesthesia Editor Dr. Debnath Chatterjee discuss caring for pediatric patients with difficult airways.
The QT interval is normally < 450 ms in males, < 470 ms in females. Prolongation is associated with a risk of the arrhythmia torsades de pointea (TdP), a potentially life threatening ventricular arrhythmia, when drugs that further prolong the QT are administered. [More…]
Liver transplant surgery may be divided in to three stages: the preanhepatic (or dissection) stage, the anhepatic stage, and the neohepatic stage. Each stage yields specific anesthetic considerations. [More…]
In patients with liver disease the most common cause of hypocalcemia is hypoalbuminemia. However, liver transplantation typically involves transfusion of large quantities of blood products, which contain the calcium-chelating agent sodium citrate. [More…]
Extracorporeal Shockwave Lithotripsy (ESWL) is a procedure that involves targeting renal or ureteral stones with electromagnetic shocks that work to break up the stones into smaller fragments. Ideally, these smaller fragments can then be excreted via urine without additional instrumentation or interventional support. [More…]
Liposuction can be performed under general anesthesia, deep or conscious sedation, or as a purely “tumescent technique.” The tumescent technique uses a “wetting solution” to control intra-operative and post-operative pain as well as bleeding specifically during liposuction procedures, facilitating the procedure. [More…]
Defined as a conversation or exchange of information between two individuals in a “protected (i.e. confidential) relationship,” such as between an attorney and client, husband and wife, priest and penitent, and doctor and patient. [More…]
The safety of lasers depends on the wavelength of the laser as well as the application of the laser. Common hazards of laser use include [Cont’d]
One of the most feared complications of laser surgery of the larynx is fire in the airway. So-called “regular” endotracheal tubes can present some issues when performing microlaryngeal surgery with a laser. [More…]
CO2 Subcutaneous Emphysema • Occurs with insufflation of the extraperitoneal space. May be accidental or intentional. • Signs: Elevated ETCO2 after initial plateau, crepitus [More…]
Numerous studies and meta-analysis have documented an increase in bispectral index (BIS) values on patients who receive ketamine. This increase has been noted in patients maintained on both intravenous and inhalational anesthesia. [More…]
Drug Class: Phencyclidines How it differs from most other induction agents: In addition to being able to induce anesthesia, it also has significant analgesic properties Proposed analgesic benefits: Ketamine has been shown to inhibit nociceptive central hypersensitization. It also has been shown to reduce the incidence of acute tolerance after opioid administration. [More…]
Jet ventilation: forced “inspiration” using high pressure oxygen sent directly into the airway (without an endotracheal tube); “expiration” is passive. Can be performed supraglottic, infraglottic, or transtracheal. [More…]
Ischemic Optic Neuropathy (ION) is the most common cause of postoperative visual loss. This can be seen in various surgeries, most notably cardiac, head and neck, robotic prostatectomies, prone positioned spine surgeries. [More…]
Ionizing radiation is a type of energy released by atoms in the form of electromagnetic waves. Occupational exposure to ionizing radiation can potentially impact first responders during an emergency response (such as during a nuclear power plant emergency), and if radiation doses are high enough first responders may develop skin burns or acute radiation syndrome. […]
Blood passing through areas of absolute shunt receives no oxygen (V/Q = 0), therefore, arterial hypoxemia resulting from intrapulmonary shunt is minimally responsive to supplement oxygen. Shunt effect (venous admixture or low V/Q) is the more common clinical scenario in which areas of lung have poor alveolar ventilation compared to the degree of alveolar perfusion […]
Intraoperative fluid management for infants is complex and often presents challenges to the anesthetic and surgical teams. Typical intraoperative practice involves administration of IV fluids to meet maintenance fluid requirements, replace any fluid deficits as a result of pre-operative fasting and disease-specific loses, in addition to ongoing losses incurred during the surgical procedure. [More…]
Anatomy: The brachial plexus arises from the cervical nerves C5 through C8 as well as T1. It originates from the anterior primary rami of these nerves and after leaving their corresponding intervertebral foramina, these nerves run anterolaterally and inferiorly where they end up between the anterior and middle scalene muscles. [More…]
Complications include: Ipsilateral phrenic nerve block resulting in diaphragmatic paresis occurs in 100% of patients undergoing interscalene blockade, even with dilute solutions of local anesthetics, and is associated with a 25% reduction in pulmonary function. Involvement of the vagus, recurrent laryngeal, and cervical sympathetic nerves is rarely significant, but a patient experiencing symptoms related to […]
An ipsilateral phrenic nerve block occurs in almost 100% and leads to a 25% reduction in pulmonary function. This procedure is therefore contraindicated in anyone with respiratory insufficiency or a contralateral nerve palsy. [More…]
Indications: patients with hemodynamic instability or severe LV systolic dysfunction. Contraindications: Severe peripheral vascular disease (PVD) of the aortoiliac and femoral arteries – due to increased risk of lower extremity ischemia. Severe aortic valve insufficiency (AI), because their AI will be worsened by the balloon pump. [More…]
Chronic hypophosphatemia is associated with short stature, rickets phenotype (bowing of the legs), and bone pain. [More…]
September 2019: Dr. T. Wesley Templeton and OpenAnesthesia Editor Dr. Debnath Chatterjee discuss one-lung ventilation in children.
A reasonable alternative option for postoperative pain relief other than a femoral nerve block. This technique can be used for: Lower leg, foot and ankle surgery in combination with a popliteal-sciatic nerve block Knee procedures (Arthroscopy, Patellar surgery, ACL, MCL Reconstruction) Benefits of adductor canal block (1) Targeted sensory blockade Limited quadriceps weakness to facilitate […]
Resources and References: LGBT-who? Decoding the ever-changing acronym. Washington Post. https://www.washingtonpost.com/news/soloish/wp/2016/06/10/lgbt-who-decoding-the-ever-changing-acronym/?utm_term=.916a98c26a1b The asterisk: Why you actually should(n’t) put the * in the acronym. The Manitoban. http://www.themanitoban.com/2014/04/asterisk/19979/ ‘Latin@’ Offers A Gender-Neutral Choice; But How To Pronounce It?NPR.org https://www.npr.org/sections/thetwo-way/2013/01/07/168818064/latin-offers-a-gender-neutral-choice-but-how-to-pronounce-it Website: It’s Pronounced Metrosexual http://itspronouncedmetrosexual.com Pregnant Man by Trystan Reese, The Moth https://themoth.org/stories/pregnant-man Academies IoMotN. The Health of […]
December 2018 Submit your feedback on this video here: https://goo.gl/forms/v0Wxj8QuZcoELcrB3
November 2018: Dr. David Polaner and OpenAnesthesia Editor Dr. Debnath Chatterjee discuss the Pediatric Regional Anesthesia Network (PRAN).
Mid Esophageal 4 Chamber View: In this view, the lateral wall of LV as well as the septal wall are visualized. The lateral wall is supplied by the left circumflex artery (LCX) and the septal wall is supplied by perforating branches of the left anterior descending artery (LAD) and the posterior descending artery (PDA). You can […]
May 2018: Myron Yaster and OpenAnesthesia Editor Dr. Debnath Chatterjee discuss the opioid epidemic and pediatric anesthesia.
This activity will introduce you to the basics of using electroencephalography (EEG) to recognize the altered states of arousal caused by commonly used anesthetic drugs. See the new IARS CME activity at EEG for Anesthesia!
Supported by an educational grant from Masimo Corporation.
August 2018: Dr. Randall Flick and OpenAnesthesia Editor Dr. Debnath Chatterjee discuss the topic of anesthetic neurotoxicity.
Definition Ankle blocks can be performed for some operations involving the foot and toes. Blocks can be performed on three superficial nerves (superficial peroneal, sural, and saphenous) and two deep nerves (deep peroneal and posterior tibial). The decision to block individual nerves is determined by the location of the surgery and analgesic distribution of these […]
Definition Bronchial hyperreactivity may last as long as 6 weeks following an upper respiratory tract infection, of which up to 95% are of viral etiology. In the acute phase both chemical mediators (bradykinin, prostaglandin, histamine, and interleukin) and neurologic reflexes contribute to morphologic and functional changes in the respiratory epithelium. Patients requiring anesthesia during this […]
Definition Upregulation refers to an increase in the density of beta-adrenoceptors on the surface membranes and is modulated by a multitude of pharmacologic and pathophysiologic factors. Beta-blockers cause subtype-specific upregulation such that nonselective beta-blockers increase the density of both beta1- and beta2-adrenoceptors whereas beta1-selective antagonists upregulate only beta1-adrenoceptors. As a consequence of increased sympathetic tone, […]
Name: Adam W. Amundson, MD Current Institution: Mayo Clinic, Rochester, MN Current Position: Senior Associate Consultant Anesthesiologist Regional Fellowship (where and when): Mayo Clinic, Rochester, MN; 2013-2014 Who would you consider your greatest mentor? Hugh M. Smith, MD, PhD Specific interest in regional anesthesia/acute pain: Ultrasonography, Enhanced Recovery After Surgery (ERAS) Protocols, Outcomes based research, […]
Biochemical Concepts Vascular smooth muscles are affected by both agonists (which induce contraction) and antagonists (which induce relaxation). The classic example of agonists/antagonists is epinephrine, whose actions depend on the binding site (which is dependent on the concentration, with beta agonism predominating at low doses, and alpha agonism taking over at higher doses). Alpha-1 receptors, […]
Name: Adam Niesen, MD Current Institution: Mayo Clinic, Rochester, MN Current Position: Assistant Professor of Anesthesiology; North Division of Anesthesia Education Director Regional Fellowship (where and when): Mayo Clinic, 2008-2009 Who would you consider your greatest mentor? It is difficult to choose just one. There have been a number of folks that have provided excellent […]
Catecholamine surges are thought to be pathogenic in stress (takotsubo) cardiomyopathy (1). This catecholamine induced injury causes ventricular ballooning, dysfunction, and in some cases dysrhythmia and sudden death. The diagnosis is confirmed with echocardiography or cardiac magnetic resonance imaging. Coronary angiography may be necessary to rule out ischemic cardiomyopathy in some cases. Troponin levels are […]
CPP is defined as MAP-ICP (or MAP-CVP, if CVP>ICP). Cerebral perfusion pressure is the major determinant of cerebral blood flow (CBF). At low and high levels of CPP, CBF is linearly related to CPP- illustrated by the well-known plot of CBF vs. CPP published by Lassen in 1959 (see figure). Along the plateau, cerebral autoregulation […]
In a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases. Ptotal= P1+P2+….Pn The partial pressure of a gas is the pressure exerted by that gas on its container independent of other gases. Since each gas in a mixture is at the same […]
Ventilatory strategies in patients with ARDS (Acute Respiratory Distress Syndrome) are based on clinical trial data from numerous large prospective clinical trials. Current strategies focus on: Limiting tidal volume (6ml/kg predicted body weight) to avoid volutrauma Formula for predicted body weight: Males: PBW (kg) = 50 + 2.3 (height (in) – 60); Females: PBW (kg) […]
Brain death is defined as an “Irreversible cessation of all functions of the entire brain, including the brainstem”. Brain death is a relatively new concept originating in the 20th Century with the advent of Mechanical Ventilation & Organ Transplantation. It led to a redefining of death- and this brain death concept was subsequently advanced through […]
The essence of acute CNS injury management is to minimize secondary injury related to hypoxia, hypoperfusion, & further mechanical damage (such as evacuating a subdural hematoma causing mass effect & herniation). Acute spinal cord injury management involves: Spine immobilization. Airway management if necessary. Maintaining spinal cord perfusion (which may be exacerbated by traumatic hemorrhage and/or […]
Diabetes Insipidus (DI) is characterized by the production of copious amounts of dilute urine. Awake patients with intact hypothalamic thirst mechanisms will be thirsty and may be able to compensate for acute or chronic DI. However, anesthetized or critically ill patients cannot and must receive fluid replacement and hormonal therapy (in the case of central […]
There are essentially two roles for cerebrospinal fluid drainage in cerebral aneurysm surgery. First, is the need to reduce brain bulk (by draining the ventricles) in order to limit retraction injury and facilitate access to aneurysms at the base of the brain (usually Circle of Willis). This is typically accomplished with a lumbar CSF drain. […]
An adult has approximately 150ml of cerebrospinal fluid (CSF) and produces about 500ml per day. Therefore the CSF turns over about 3x per day (continually produced and reabsorbed). Interference with the normal reabsorption (for example by clogging of arachnoid granulations with subarachnoid hemorrhage) causes communicating hydrocephalus. Interference with drainage of CSF from any or all […]
Electroconvulsive therapy causes a generalized tonic clonic seizure by electrical stimulation of the brain. Cerebral blood flow and metabolism increase dramatically. From a cardiovascular standpoint, there is an initial parasympathetic surge (primarily during the electrical stimulation) with severe bradycardia or asystole. This is followed by a sympathetic surge causing hypertension and tachycardia. Source Mayo C, […]
Remifentanil is a potent intravenous short-acting synthetic opioid. It acts as a µ-receptor agonist. Remifentanil is rapidly hydrolyzed by plasma and tissue esterases. It is unique in that it displays no context-sensitivity. In other words, it does not accumulate with prolonged infusion. The context-sensitive half-life is ~4 minutes. It is useful for procedures requiring profound […]
Advances in surgical and perioperative care have reduced stroke rates following coronary artery bypass grafting (CABG). Post-CABG stroke rates are now in <5%. Valvular surgery carries a much higher stroke risk than CABG- likely due to increased cerebral embolic events. Perioperative strokes after CPB can be separated into ‘early’- present at extubation; and late- occurring […]
The American College of Cardiology (ACC) and the American Heart Association (AHH) have collaborated to develop a set of clinical practice guidelines using scientific evidence in order to standardize the preoperative cardiac evaluation of patients undergoing non-cardiac surgery. Recommendations are based on a known history of or risk factors for cardiac disease as well as […]
Formally speaking, “Shock is defined as a state of cellular and tissue hypoxia due to reduced oxygen delivery and/or increased oxygen consumption or inadequate oxygen utilization” (Gaieski). Shock is classified into four different categories: distributive, hypovolemic, cardiogenic, and obstructive. There can also be shock with a combination of the aforementioned categories. Distributive shock is characterized […]
The most recent ACC/AHA guidelines for perioperative evaluation and management were updated in 2014. For pre-operative cardiac assessment of coronary artery disease, the decision to delay surgery for additional workup can be made by following the suggested steps: Step 1: If it is an emergency, proceed to surgery. Step 2: If the patient is having […]
Muscular dystrophy is a group of hereditary diseases characterized by painless degeneration and atrophy of skeletal muscles. There is symmetric skeletal muscle weakness/wasting without denervation (sensation and reflexes are intact). X-linked recessive types (Duchenne and Becker muscular dystrophies) are the most prevalent types of muscular dystrophy. Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) […]
Name: Carrie R. Guheen, MD Current Institution: Hospital for Special Surgery, New York, NY Current Position: Assistant Attending Anesthesiologist, Hospital for Special Surgery; Clinical Instructor of Anesthesiology, Weill Cornell Medical College Regional Fellowship (where and when): Hospital for Special Surgery, New York, NY, 2010-2011 Who would you consider your greatest mentor? She probably doesn’t realize […]
Nerve damage tends to occur via two main mechanisms: pharmacologic toxicity and needle trauma. Both are uncommon and usually self-limited in nature. The risk of nerve injury from regional nerve blocks is less than that associated with neuraxial techniques and is often related to pain during needle placement or during injection of local anesthetic. It […]
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The ASA has produced a set of guidelines regarding the delivery of office-based anesthesia and the special considerations this brings. It defines the expected medical leadership roles of the practice and the need for compliance with building standards laid out by state and federal bodies. Regarding clinical care, the document states that the patient (given […]
As of May 2015, 123,331 people waiting for life-saving organ transplants in the U.S. Of these, almost 100,000 await kidney transplants. Over 100,000 Americans are on the waiting list in need of an organ, yet on average there are only 30,000 transplants performed each year. Currently, in the United States organ donation is done only […]
Lateral decubitus position (LDP) is inherently unstable and predisposes patients to compression and stretch injury. Damage to brachial plexus is one of the most frequent positioning injuries when patients are in lateral decubitus position. The brachial plexus is anchored in the neck to the transverse processes of the cervical vertebrae. In upper arm, brachial plexus […]
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Female gender is the strongest patient specific predictor of PONV, followed by history of PONV or motion sickness, non-smoking status, and younger age. Anesthesia related factors include the use of volatile anesthetics, duration of anesthesia, perioperative opioid use, and use of nitrous oxide. Certain types of surgery may be associated with increasing the frequency of […]
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It is generally understood that direct electromagnetic induction in looped cables associated with the patient are responsible for the excessive heating, and it is on this theory that present guidelines are based. In general, magnetic resonance (MR) imaging is considered to be a relatively safe diagnostic modality; however, the use of radiofrequency coils, physiologic monitors, […]
Absolute Contraindications to MRI include: Pulmonary artery monitoring catheters and temporary transvenous pacing leads Intra-aortic balloon pumps Left and right ventricular assist devices Epicardial leads, retained transvenous leads, fractured leads Ferromagnetic vascular clips Metallic foreign body (i.e. shrapnel, metal splinters, welding splinters, bullets, grenade fragments) Spinal cord neurostimulators Claustrophobia Body piercings Vascular access port Implants […]
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Crystalloids and colloids are the primary options for intravenous fluid resuscitation. Crystalloids fluids such as normal saline typically have a balanced electrolyte composition and expand total extracellular volume. Colloid solutions (broadly partitioned into synthetic fluids such as hetastarch and natural such as albumin) exert a high oncotic pressure and thus expand volume via oncotic drag. […]
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Indications for use: The LMA device is appropriate for elective cases, as a rescue device, in expected difficult airway situations or in fasting patients. It can be used in CPR situations if the patient is profoundly unresponsive. Contraindications include morbidly obese individuals, pregnant women > 14 weeks gestation, individuals at increased risk for aspiration, patients […]
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The Health Insurance Portability and Accountability Act of 1996 (HIPAA) includes Standards for Privacy of Individually Identifiable Health Information (“Privacy Rule”). The Privacy Rule established a set of national standards for the protection of certain health information. The Privacy Rule addresses the use and disclosure of individuals’ health information (“protected health information”, PHI) and the […]
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Neuropathic pain results from damage to an afferent pathway that can be the result of a disease, trauma, or dysfunction. Ectopic nerve activity/Peripheral Sensitization This mechanism is responsible for pain sensed in the absence of external stimuli. Spontaneous nerve activity has been shown in both the injured nerve as well as uninjured neighboring nerves. This […]
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Incidence: 60% Shown to be consistent regardless of country, procedure or health care system Who is at greatest risk? Age > 7 years Personality: Children who are shy, inhibited, introverted are at increased risk Children who have anxious parents Prior upsetting hospital experience Only children (children without siblings) Children who did not attend pre-school Why […]
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In utero fetal circulation is different from adult circulation in 4 primary ways: Umbilical venous blood bypasses the liver by way of the ductus venosus Blood is shunted from right atrium to left atrium through the foramen ovale Blood ejected from the right ventricle bypasses the lungs by traveling through the ductus arteriosus and into […]
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Ionizing radiation is a type of energy released by atoms in the form of electromagnetic waves. Occupational exposure to ionizing radiation can potentially impact first responders during an emergency response (such as during a nuclear power plant emergency), and if radiation doses are high enough first responders may develop skin burns or acute radiation syndrome. […]
Pulmonary diffusing capacity is often measured by Diffusion capacity of the Lungs for carbon monoxide (DLCO). In essence, this measures how much CO can pass from the alveoli to the blood in the pulmonary capillaries, thus giving clinicians the broader idea of how much inhaled gas can pass into the blood through the lungs. The […]
Invasive MRSA is typically treated with vancomycin or daptomycin. Vancomycin is a glycopeptide that inhibits cell wall synthesis. Although this is usually the first choice, there is growing concern regarding emerging resistance to Vancomycin and tissue penetration is limited to bone, lung, and CSF. Daptomycin is a cyclic lipopeptide bactericidal antibiotic that ultimately causes depolarization […]
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The immediate physiologic response to drowning is breath-holding. After breath-holding, involuntary laryngospasm can occur with entry of fluid into the oropharynx and larynx. At this point, oxygen stores are depleted quickly leading to hypoxia as well as hypercarbia and acidosis. Alternatively, if laryngospasm does not occur, the drowning individual will quickly begin gasping for air […]
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Strong ions are cations and anions that exist as charged particles dissociated from their partner ions at physiologic pH. Thus, these ions are “strong” because their ionization state is independent of pH. The Strong Ion Difference (SID) is the difference between the positively- and negatively-charged strong ions in plasma. This method of evaluating acid-base disorders […]
Surgical stress may lead to a catabolic state. One consequence of this is lipolysis or the hydrolysis of triglycerides into glyceride and free fatty acids. It is thought that lipolysis is largely a result of stimulating beta-2 adrenergic receptors. The beta-2 agonism results in an increase in intracellular cAMP and downstream activation of triglyceride lipase […]
Cytochrome P450 (CYP) is a membrane bound protein present in most tissues in the body. It is a member of a superfamily of proteins known as hemoproteins – those that contain a heme group that is active in the catalytic mechanism of these various proteins. Other members of this family in humans include hemoglobin, myoglobin, […]
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The effects of insulin, a hormone secreted by pancreatic islet beta-cells, are numerous, leading to biochemical changes in nearly every tissue in the body. Among its many functions, insulin induces glucose uptake by tissues and glycogen synthesis in the liver and muscles. By inhibiting lipase, insulin additionally limits free fatty acid release from adipose tissue […]
Hypercapnia, or high PaCO2, can occur in numerous scenarios during anesthetic and post-anesthetic care. In the operating room, hypercapnia is typically detected with capnography.; however, this monitor is not always available outside of the operative environment. When assessing a patient with known or suspected hypercapnia, one should assess for a number of potential causes: Hypoventilation […]
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Analgesia in patients with renal disease and who require opioids has obvious risks and prescribing their use in this population should be performed with caution. The list below show the common opioids used. Typically Avoided: Codeine: Metabolized by the liver to codeine-6-glucuronide (81%), norcodeine (2%), morphine (0.6%), M3G (2%), M6G (0.8%) and morphine (2.4%). Morphine […]
For skeletal muscle, Na+ mediated depolarization (Phase 1) is quickly followed by repolarization (Phase 3). Repolarization is mediated by closure of the Na+ channels responsible for depolarization, and opening of voltage-gated K+ rectifier channels, which allows for potassium efflux. These K+ channels will remain open and hyperpolarize the cell membrane is restored to its resting […]
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Respiratory quotient is the ratio of VCO2 and VO2: RQ = CO2 eliminated/O2 consumed Under typical metabolic conditions with stable respiratory function, the range of RQ in human metabolism is approximately 0.7 to 1.0. A value of 1.0 is consistent with pure carbohydrate oxidation, whereas a value of 0.7 is consistent with pure fat oxidation. […]
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Normal mixed venous oxygen tension (PvO2) is approximately 40 mmHg, representing the balance between oxygen consumption and oxygen delivery. A true PvO2 measurement must come from a mixed venous blood sample containing venous drainage from the SVC, IVC, and the heart. Thus, the sample should be obtained from a pulmonary artery catheter. There are several […]
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The liver serves several metabolic functions within the body including protein synthesis and metabolism. The liver is responsible for an array of proteins. Endocrine proteins produced by the liver include angiotensinogen, thrombopoietin, and insulin-like growth factor I. In children, the liver is primarily responsible for heme synthesis. In adults, bone marrow supplants heme production. However, […]
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Synthetic function of liver include: Synthesis of plasma proteins Acute phase proteins Albumin Clotting factors Binding proteins Gluconeogenesis Cholesterol / lipoproteins Immunoglobulins Hormones Urea and bile *Almost all plasma proteins synthesized by liver except: Gamma-globulins (RES), factor VIII (Vascular/glomerular endothelium, and sinusoidal cells of the liver), Factor III (tissue endothelial), vWF (endothelial) Measures of synthetic […]
In a nutshell, patient-controlled analgesia (PCA) provides superior postoperative analgesia and improved patient satisfaction compared to traditional PRN analgesic regimens because the person feeling the pain is in control, and they FEEL in control. Every individual is unique when it comes to pain tolerance, analgesic needs, and drug pharmacokinetics and metabolism. This makes it difficult […]
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Em = resting membrane potential of the cell, -90 mV. Maintained by the Na-K ATPase, which pumps K+ INTO the cell and Na+ OUT, as well as the Na-Ca exchanger, which pumps calcium OUT of the cell. Et = threshold potential, -65 mV Phase 0 = resting cell is brought to Et → rapid depolarization […]
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Tramadol and its active metabolite (O-desmethyltramadol) binds to μ-opioid receptors in the CNS causing inhibition of ascending pain pathways and altering the perception of and response to pain. Tramadol also inhibits the reuptake of norepinephrine and serotonin, which are neurotransmitters involved in the descending inhibitory pain pathway responsible for pain relief. Tramadol is indicated for […]
Bi-ventricular (“bi-vent”) pacing falls under the larger category of Cardiac Resynchronization Therapy (CRT) with the primary goal of resynchronizing both ventricles through simultaneous pacing. This can improve myocardial contractile function, reduce functional MR, and reverse cardiac remodeling associated with heart failure. The indications for bi-vent pacing have been changing regularly as more research is being […]
Definition The textbook definition for drug tolerance is as follows “the need for increasing doses to maintain a defined pharmacodynamic effect.” What this means clinically is the development of shortened duration and decreased efficacy of certain opioid effects such as analgesia, central nervous system depression, and euphoria. These patients will also experience an increase in […]
Peripheral nerves have three layers of connective tissue: Epineurium – is the outermost layer of connective tissue that is continuous with the dura mater. It also includes the connective tissue in between any fascicles (bundles) within the nerve. Perineurium – is the connective tissue sheath that surrounds a fascicle of axons. Endoneurium – is the […]
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Awareness results partly from the inability to accurately measure the depth of anesthesia. There is no monitor that can guarantee no intraoperative awareness/recall. It is primarily subjectively judged by observing trends in heart rate, blood pressure, lacrimation, and movement. Level of consciousness monitors (depth of anesthesia monitors) can also be helpful, especially in certain patients […]
Equilibrium: State in which constant amount of molecules jump from the liquid phase to gas phase and visa versa. Vapor pressure: The pressure exerted by the gas phase on the walls of the container at constant temp and equilibrium. Saturated Vapor pressure (SVP): When the gas phase on top of the liquid phase is saturated […]
The Blood Gas Partition Coefficient is also known as Ostwald coefficient for blood–gas. A partition coefficient is the ratio of the concentrations of a compound in one solvent to the concentration in another solvent at equilibrium. The blood/gas partition coefficient describes how the gas will partition itself between the two phases after equilibrium has been […]
Butyrylcholinesterase (pseudocholinesterase) is a serine hydrolase synthesized in the liver and present in the plasma. It is structurally and functionally related to acetylcholinestrase, an enzyme that is that catalyzes the hydrolysis of acetylcholine. Butyrylcholinesterase catalyzes the hydrolysis of esters of choline, including acetylcholine, butyrylcholine, and succinylcholine, as well as the hydrolysis of esters such as […]
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Lorazepam is a benzodiazepine that works through activation of GABAA to increase the activity of GABA which in turn reduces neuronal firing in the brain. The metabolism of lorazepam is different than other benzodiazepines as it is metabolized in the liver by the process of glucuronidation. There are two other benzodiazepines metabolized in this fashion […]
Numerous systems in the body produce signals to induce vomiting. Some of these systems include the cerebral cortex, vestibular system, and GI tract. Additionally, the Chemoreceptor Trigger Zone (CTZ), located in the area postrema on the floor of the fourth ventricle, is not protected by a true blood-brain barrier and is therefore exposed to toxins […]
At the turn of the 20th century, Meyer and Overton independently discovered the correlation between lipid solubility and anesthetic potency. Meyer concluded that all chemically indifferent, fat-soluble agents, would function as anesthetics. The presumed mechanism was related to the notion that the agents were able to act at the lipid bilayer of the cell membrane, […]
Basic pharmacokinetic principles NO has a blood:gas partition ratio of 0.47 and is thus 30 times more soluble in blood than nitrogen, which has a blood:gas partition ratio of 0.015 Thus, NO accumulates in closed gas spaces that contain N2 faster than the N2 can diffuse out. In other words, the highly blood soluble NO […]
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In general, antibiotics as a class potentiate both depolarizing muscular blocking drugs and nondepolarizing neuromuscular blocking drugs to varying degrees. Aminoglycosides have been reported to have a magnesium like effect on the neuromuscular junction. Amphotericin induced hypokalemia has been observed to potentiate. Lincosamides (clindamycin, lincomycin) principal action is direct effect on muscle. Tetracycline administration chelates […]
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Angiotensin Converting Enzyme Inhibitors (ACE-I) prevent the conversion of angiotensin I to angiotensin II, which disrupts the renin-angiotensin-aldosterone system (RAAS). Failure to convert angiotensin I to angiotensin II results in relative vasodilation, as angiotensin II is a potent vasoconstrictor. Angiotensin II also causes vasoconstriction of afferent and efferent arterioles of the renal microvasculature, which preferentially […]
Alpha receptors Alpha-1 Predominantly expressed on vascular smooth muscle. Agonists cause increase in tone resulting in hypertension (and reflex bradycardia). Think phenylephrine. Antagonists have the opposite effect. Alpha-2 Expressed on presynaptic receptors. Agonist activity results in feedback inhibition of sympathetic outflow. Thus, a decrease in BP and bradycardia (dexmedetomidine or clonidine). Alpha Blockers Phenoxybenzamine Irreversible […]
Hypokalemic periodic paralysis is a disorder characterized by episodes of weakness, sparing the respiratory muscles, with a matching fall in serum potassium that lasts anywhere from a few hours to a few days. Hypokalemic periodic paralysis is a “channelopathy” caused by defective sodium, calcium or potassium ion-channels. Episodes of hypokalemia cause weakness by partial depolarization […]
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Antibiotics, particularly penicillins and cephalosporins are a common cause of drug allergy in surgical patients. Allergic reactions occur in 1% to 4% of all β-lactam administrations, but only 0.004% to 0.015% of these reactions result in anaphylaxis. As great as 2% of the population is allergic to penicillin. Among patients with a penicillin allergy, 2-7 […]
Oliguria is defined as having a urine output of <0.5mL/kg/hour. While urine output does not always correlate with glomerular filtration rate (GFR) and rarely results in acute kidney injury, it does serve a purpose in identifying the level of kidney injury defined by the RIFLE and AKIN (Acute Kidney Injury Network) criteria. One should consider […]
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Acetazolamide is a potent inhibitor of carbonic anhydrase, which results in wasting of sodium and bicarbonate in the proximal tubule, which results diuresis and also alkalinizes the urine. Lab finding with chronic use (i.e. for glaucoma treatment): Metabolic acidosis due to decreased H+ secretion into the proximal tubule, and increased bicarbonate excretion into the tubule […]
CO2 Subcutaneous Emphysema Occurs with insufflation of the extraperitoneal space. May be accidental or intentional. Signs: Elevated ETCO2 after initial plateau, crepitus Treatment: Stop peritoneal insufflation. Once hypercapnia has been resolved, laparoscopy may resume with lower insufflation pressures. The presence of cervical crepitus is not a contraindication for extubation. Pneumothorax Occurs when there exists a […]
Liver transplant surgery may be divided in to three stages: the preanhepatic (or dissection) stage, the anhepatic stage, and the neohepatic stage. Each stage yields specific anesthetic considerations. The preanhepatic stage begins with incision and ends with cross-clamping of the portal vein, the hepatic artery, and the inferior vena cava (IVC) or hepatic vein. The […]
Succinylcholine dosing for optimal intubating conditions should be based on total body weight. Onset of complete neuromuscular blockade largely remains similar despite variability in dosing. Duration of action of neuromuscular blockade is increased with more liberal dosing. Optimal succinylcholine dosing for morbidly obese individuals (BMI > 4) was evaluated by randomized controlled trial with outcomes […]
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Amyotrophic lateral sclerosis (ALS) is a degenerative disease process that produces both upper and lower motor neuron degeneration. It most commonly affects men 40 to 60 years of age. Frequent initial manifestations include skeletal muscle atrophy, weakness, and fasciculations. With time, atrophy and weakness involve most of the skeletal muscles, including the tongue, pharynx, larynx, […]
Hyperthyroidism is defined as a hypermetabolic state that is characterized by elevated peripheral thyroid hormones. Subclinical hyperthyroidism: low TSH levels in the setting of normal free peripheral thyroid hormone levels (T3, T4). Overt hyperthyroidism: low TSH is seen in the setting of elevated T3 and/or T4. As always, a thorough medical history and physical exam […]
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Porphyrias are a set of autosomally inherited metabolic disorders that are the result various defects in heme synthesis. Broadly, they can be classified into inducible, and non-inducible forms. Inducible porphyrias (i.e. Acute Intermittent Porphyria) can present with acute neurological and/or GI symptoms. Patients may have anxiety, confusion, autonomic instability (manifested as hypertension or tachycardia), emesis, […]
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Innervation of the Abdominal Wall The anterior rami of spinal nerves T7-L1 innervate the anterolateral abdominal wall. The anterior divisions of the intercostal nerves (T7-11) enter the abdominal wall between the internal oblique and transversus abdominis muscles; they continue in this space anteriorly until they pierce and innervate the rectus abdominis and end as anterior […]
Primary adrenal insufficiency (Addison’s disease) is defined by failure of adrenal glands to provide sufficient quantities of glucocorticoid, mineralocorticoid, and androgen hormones. It is most commonly caused by bilateral adrenal destruction from autoimmune disease. Secondary adrenal insufficiency is defined as an ACTH deficiency due to either a failure of ACTH or CRH production from hypothalamic-pituitary […]
Several risk factors for post-operative cardiac complications after major noncardiac surgery have been identified. Goldman et al. in 1977 published a prospective study of 1001 patients over the age of 40 and identified “nine independent significant correlates of life-threatening and fatal cardiac complications”. The Goldman cardiac risk index emerged this data. Subsequently, several modified risk […]
Carotid endarterectomy is an procedure performed to remove plaque from the endothelium of the common carotid artery in order to improve flow through the internal carotid and thus perfusion of intracranial structures including the brain. Several randomized controlled trials have proven benefit of this procedure in symptomatic patients with 70-99% stenosis. Different sources quote risk […]
Cardiac tamponade is a clinical syndrome resulting from the accumulation of fluid in the pericardial space resulting in reduced ventricular filling and subsequent cardiovascular compromise. The diagnosis of cardiac tamponade is made clinically, not with imaging. Imaging such as echocardiography; however, can help aid in, and confirm, the diagnosis. There are classically 3 phases of […]
The alveolar gas equation estimates alveolar oxygen content given a few readily measurable variables. The pAO2 derived from performing the calculation can then be used to discern the degree of shunt present in a patient. Practical simplification of the complex formula allows for the following equation: pAO2 = FiO2 (Patm – pH20) – (paCO2/RER) Where […]
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The spinal cord receives blood supply from two posterior arteries (25%) and one anterior spinal artery (75%). The posterior arteries supply the sensory tracts in the spinal cord and receive flow from posterior and inferior cerebellar arteries, the vertebral arteries, and the posterior radicular arteries. The anterior artery supplies the motor tracts and is formed […]
Imaging the aortic valve is best accomplished in the mid-esophageal short and long axis views. The ME AV SAX demonstrates the noncoronary cusp superiorly, the right coronary cusp inferiorly, and the left coronary cusp to the right. As the probe is withdrawn cephalad from this view one can evaluate the sinus of Valsalva and by […]
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When interpreting masses on a CXR, it can sometimes be very difficult to discern whether a mass originates in the lung or in the mediastinum. There are a few ways that can greatly help to localize masses to the mediastinum including the following: 1. Mediastinal masses will not contain air bronchograms; and, 2. Mediastinal mass […]
The acetylcholine receptor (AChR) is a membrane protein that binds to the neurotransmitter acetylcholine (Ach). These receptors can be divided into two main types of distinct receptors, nicotinic and muscarinic. Nicotinic acetylcholine receptors (nAChR) are pentameric ligand-gated ion channels, whereas muscarinic acetylcholine receptors (mAChR) are seven-helix G-protein coupled membrane proteins. Nicotinic acetylcholine receptors (nAChR) These […]
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A retrobulbar block is frequently used for various ophthalmologic procedures including surgeries of the cornea, anterior chamber, and lens. A local anesthetic is injected into the cone formed by the four rectus muscles of the eye, thereby providing akinesia and anesthesia to ocular and extraocular muscles, with the exception of the orbicularis oculi of the […]
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Name: Jean-Louis Horn, MD, Professor of Anesthesiology, Perioperative and Pain Medicine at the Stanford University Medical Center Current Institution: Stanford University Medical Center Current Position: Chief, Division of Regional Anesthesia, Stanford University (2013 – Present) Regional Fellowship (where and when): Pain Fellowship at Vanderbilt University, Nashville, Tennessee, 1994-95 Who would you consider your greatest mentor? […]
Definition Overall, standard Basic Life Support (BLS) and Advanced Cardiac Life Support (ACLS) principles apply similarly to pregnant patients as they do to other adult patients. There are some modifications to consider: Left uterine displacement 15 to 30 degrees Consider airway edema associated with pregnancy Decreased functional residual capacity in pregnancy Chest compressions should be […]
Definition GABAb receptor agonists (such as Bacofen) lead to decrease in excitatory neurotransmission and increase in inhibitory signals. Common side effects are drowsiness, dizziness, GI problems. Signs of toxicity mainly include neurologic symptoms such as seizures, delirium, and altered mental status at doses greater than 200mg. At much higher doses, cardiac manifestations such as tachycardia, […]
Definition In a patient with a spinal cord injury (SCI), autonomic hyperreflexia (autonomic dysreflexia) is initiated by noxious stimuli below the level of cord injury. The noxious stimuli elicits a hypertensive response, which is followed immediately by a profound vagal response. In response to the increase in afterload, patient may vasodilate and appear flushed above […]
Definition Vomiting generally leads to a hypochloremic, hypokalemic (not always), metabolic alkalosis. According to Smith, “although hypokalemia is a frequent finding, Schwartz and colleagues (2003) reported in a retrospective chart review that 36% of patients with pyloric stenosis were noted to have hyperkalemia” Importantly, semi-normalization of chloride may be important (and most relevant), as data […]
Definition Enoxaparin, like any LMWH, is derived by depolymerization of unfractionated heparin and retains UFH’s ability to activate antithrombin and thereby provide anticoagulation. Largely secondary to its smaller molecular size, enoxaparin binds less to plasma proteins, macrophages, and endothelial cells, thereby promoting a more reliable dose-response relationship and longer plasma half-life compared to UFH. Compared […]
Definition The average adult liver synthesizes approximately 15 g of albumin per day with a half-life of approximately 20 days, with 4 percent degraded daily. Thus if hepatic protein synthesis came to a halt, it would not be noticeable for several days. Hypoalbuminemia is somewhat nonspecific for liver dysfunction since other conditions may be responsible […]
Definition Diagnosis of myofascial pain is made by palpation of trigger points reproducing pain that is characterized as explicitly tender and narrowly localized, aching and lingering associated with stiffness, muscle spasm or muscle weakness as well as some degree of autonomic dysfunction. Trigger point palpation and reproduction of pain is consistently noted in the masseter, […]
Definition Latex is a naturally occurring compound, derived from tree sap, and used to make rubber products. The first allergic reaction to latex was reported in 1979. Since that time, it has become widely recognized that several populations are at increased risk of latex allergy. These groups include health care workers (who become sensitized by […]
Definition Lusitropy refers to the ability of the myocardium to relax following excitation contraction coupling. The removal of calcium to the endoplasmic reticulum (SR) promotes relaxation. The sarcoplasmic reticulum calcium ATPase (SERCA), NA/CA exchanger (NCX) and sarcolema CA-ATPase account for 90% removal of calcium. In essence, lusitropy is diastolic function as inotropy (or contractility) is […]
Definition The original antidepressants, phenelzine (Nardil), isocarboxazid (Marplan), and tranylcypromine (Parnate) are all irreversible inhibitors of MAO-A and MAO-B, leading to pronounced effects on metabolism of endogenous (5-HT, NE, and DA) and exogenous (tyramine) monoamines. Selegeline is a selective MAO-B inhibitor – serotonin is deaminated by MAO-A (MAO-B primarily breaks down dopamine and phenethylamine), so the risk of serotonin […]
Definition Paired t-test compares study subjects at 2 different times (paired observations of the same subject). Unpaired t-test (aka Student’s test) compares two different subjects. The paired t-test reduces intersubject variability (because it makes comparisons between the same subject), and thus is theoretically more powerful than the unpaired t-test. Subspecialty General Related Media Keyword […]
Definition Compartment syndrome occurs when volume (usually edema and/or blood) accumulates in a confined osseofascial space to the extent that delivery of oxygen to tissues is compromised. It is most common with orthopedic trauma (40% tibial shaft, 18% forearm, also femur and ankle) although 23% are caused by soft tissue trauma with no fracture. Compartment […]
Definition General Caudal epidural block involves injection of medication through the sacral hiatus, which is an arch shaped opening in the dorsal sacral surface. The sacral canal is continuous with the lumbar spinal canal, and contains the cauda equina nerve roots, spinal meninges, epidural fat and epidural venous plexus. The subarachnoid space terminates typically at […]
Definition Muscle pain is most frequently related to tension, overuse, or muscle injury from exercise or physically demanding work. It can be a sign of conditions affecting your whole body, like some infections (including the flu) and disorders that affect connective tissues throughout the body (such as lupus). One common cause of muscle aches and pain […]
Definition One lead of the low-output nerve stimulator is attached to a needle and the other lead is grounded somewhere on the patient. Lower current is required when a negative lead is attached to the needle. The reason for this phenomenon is that when the stimulating electrode is negative, the current flow alters the resting […]
Definition Side effects of anticholinesterases include bradycardia, hypotension, bronchospasm (and hypoxia), increased respiratory secretions,possibly nausea and vomiting (although this is controversial and, according to Miller (1), “Reports on the effect of anticholinesterase administration on postoperative nausea and vomiting are conflicting“), increased GI motility and secretions, miosis, and decreased intraocular pressure. Interestingly, excessive neostigmine may also lead to a depolarizing block, similar to succinylcholine. According to Nair […]
Definition Diagnosis of myofascial pain is made by palpation of trigger points reproducing pain that is characterized as explicitly tender and narrowly localized, aching and lingering associated with stiffness, muscle spasm or muscle weakness as well as some degree of autonomic dysfunction. Trigger point palpation and reproduction of pain is consistently noted in the masseter, […]
Definition A possible complication (<1% incidence cited) of thyroidectomy. Usually is unilateral resulting in paramedian position of ipsilateral vocal cord causing hoarseness and stridor, but possibly bilateral which would cause aphonia and possible airway obstruction. Subspecialty Related Media Keyword history 85%/2008 See Also: Sources PubMed
Definition When placing an IJ central line, many potential complications are similar between the right and left sides. These include inadvertent carotid artery puncture, pneumothorax, and infection. A potential complication unique tot he left IJ is related to the fact that the thoracic duct is the main lymphatic channel of the body that drains into the […]
Definition Organophosphate compounds are used as commercial insecticides (isulfoton, phorate, dimethoate, ciodrin, dichlorvos, dioxathion, ruelene, carbophenothion, supona, TEPP, EPN, HETP, parathion, malathion, ronnel, coumaphos, diazinon, trichlorfon, paraoxon, potasan, dimefox, mipafox, schradan, sevin, and dimetonor) in chemical warfare (nerve gases such as tabun and sarin) and are applied as aerosols or dusts. They can be rapidly […]
Definition TCD uses relies on the Doppler shift of sounds waves reflected off moving RBCs to measure blood flow velocity in the cerebral vessels. The most commonly monitored arteries are the middle cerebral artery and the internal carotid. Velocity increases during systole and decreases during diastole and these velocities are plotted against time, the plot […]
Definition Three-Legged Stool (15-30-40 rule) Cardiopulmonary Reserve (VO2) Patients with a VO2 max < 10 mL/kg/min are at very high risk [Bechard D et al. Ann Thorac Surg 44: 344, 1987; Bollinger CT et al. Chest 108: 341, 1995], and 15 mL/kg/min may be a reasonable cutoff [Miller’s Anesthesia, 7th ed. 2009. p 1821] Stair […]
Definition To understand the potential complications of an ilioinguinal block you must first understand the anatomy. The abdominal wall layers consist of skin, a superficial fatty layer of subcutaneous tissue (Camper fascia), a deep membranous layer of subcutaneous tissue (Scarpa fascia), deep fascia, external oblique muscles, fascia, internal oblique muscles, fascia, transversus abdominus muscles, transversalis […]
Definition The overall respiratory problem is one of restrictive lung disease. Chest wall and lung compliance are decreased from the heavy layer of fat. Subsequent decreased pulmonary compliance leads to decreased FRC (primarily a result of lowered ERV), decreased VC, and decreased TLC. The reduced FRC can result in lung volumes below the closing capacity, […]
Definition Gas Exchange Gas Exchange: improves oxygenation by re-expanding collapsed alveoli (reduced shunt) and redistributing lung water from alveolar to interstitial space, both improve V/Q matching. If too high could hyperinflate impairing blood flow increasing deadspace lowering PaO2 raising PaCO2. Respiratory Mechanics Compliance = tidal volume/(Plateau press – PEEP). CPAP/PEEP can increase, decrease, or not change compliance. Increase indicates alveolar […]
Definition What kind of pharmacologic agent is it? NSAID Mechanism of action? Not completely understood, thought to work by inhibiting prostaglandins USES: pain Pharmacokinetics Liver metabolism Renal excretion Peak: 1 hr Dose: Patients age 17 to 64: 20 mg PO once followed by 10 mg q4-6 hours prn not > 40 mg/day Patients age ≥ 65, renally impaired, and/or […]
Definition Avoiding secondary injury is of paramount importance in managing traumatic brain injury (TBI). Cerebral ischemia and hypoxia should be avoided. Hypotension and oxygen desaturation should be treated. The goal is to maintain adequate oxygen delivery to the brain to meet the rate of oxygen consumption by the brain (CMRO2). The choice of fluid should […]
Definition Doxorubicin is a chemotherapy drug that is administered intravenously. It is used in treatment of leukemia, lymphoma, breast cancer, soft tissue sarcoma, multiple myeloma, and other cancers. Side effects of doxorubicin, similar to other chemotherapy agents, include nausea and vomiting, alopecia, and neutropenia. It can also cause arrhythmias and at high doses carries the […]
Definition Cardiotoxicity is the main one that everyone expects you to know but the list is long. Acute cardiotoxicity: Atrioventricular block, bradycardia, bundle branch block, ECG abnormalities, extrasystoles (atrial or ventricular), sinus tachycardia, ST-T wave changes, supraventricular tachycardia, tachyarrhythmia, ventricular tachycardia Delayed cardiotoxicity: LVEF decreased, CHF (manifestations include ascites, cardiomegaly, dyspnea, edema, gallop rhythm, hepatomegaly, oliguria, pleural effusion, […]
Definition The Doppler shift occurs when a source of wave is moving toward or away from a receiver (or when the receiver is moving toward or away from a wave source). When the distance between a wave source and the receiver is getting smaller, the observed frequency of the wave is greater than the source […]
Definition Normal Levels of CO Normal individuals will have up to 3% CO, and smokers may have up to 9%. Patients are generally asymptomatic if < 10%, with overt signs developing at ~ 15%. Diagnosis The diagnosis of CO poisoning is made by a history of exposure (internal combustion engine exhaust, fire, improperly adjusted gas or oil […]
Definition Phosphorus Hypophosphatemia (defined as phosphate <2.5mg/dL) is reported in 17-28% of critically ill patients. It can result from increased renal excretion of phosphate, decreased absorption by the GI tract, or most commonly, an increase in intracellular movement of phosphate. Phosphate < 1.0 mg/dL may also lead to hemolytic anemia, heart failure, tachypnea, CNS symptoms (including seizures), and […]
Definition Patients with a spinal cord injury at T7 or higher are at risk for autonomic hyperreflexia. Normally, the reflexic response to cutaneous, visceral (bladder), and proprioceptive stimuli are to some extent attenuated by descending, inhibitory impulses. However, in patients with SCI, these impulses may be curtailed, leading to uninhibited spinal cord reflexes and consequent vascular instability – initially […]
Definition The total work of breathing is the sum of the work expended to overcome the resistance to airflow through the airways (Raw) and the work expended to overcome the resistance of the chest wall (Rcw). If minute ventilation is constant, Raw increases with increasing respiratory rate and Rcw increases with decreasing respiratory rate. As […]
Definition Step 1: Pain a. Non-opioid i. Paracetamol ii. ASA iii. NSAID b. Adjuvant i. steroids ii. anxiolytics iii. antidepressants iv. hypnotics v. anticonvulsants vi. antiepileptic-like gabapentinoids (gabapentin and pregabalin) vii. membrane stabilizers viii. sodium channel blockers ix. NMDA receptor antagonists for the treatment of neuropathic pain x. cannabinoids Step 2: Pain persisting or increasing: […]
Definition Pipeline sources are not trouble-free: Consider contamination (particles, bacteria, viral, moisture), inadequate pressure, excessive pressures, and accidental crossover (switch between oxygen and some other gas such as nitrous oxide or nitrogen). The two more frequent problems related to pipeline supply are crossover and inadequate pressure. CROSSOVER This rare situation has been almost reduced to […]
Definition Emphysema is defined by destruction of airways distal to the terminal bronchioloe. Physiology of emphysema involves gradual destruction of alveolar septae and of the pulmonary capillary bed, leading to decreased ability to oxygenate blood. The body compensates with lowered cardiac output and hyperventilation. Thus, V/Q mismatch results in relatively limited blood flow through a […]
Definition Type 1: Quantitative disease dDAVP trial Type 2: Qualitative disease dDAVP trial; unlikely to be effective Type 3: Autosomal recessive d/o with virtually undetectable levels vWF Acquired vWF deficiency Trial of dDAVP, if not responding, use vWF concentrate or cryprecipitate if emergency If antibody mediated acquired vWF deficiency, use IVIG Minor bleeding/Minor surgery dDAVP, […]
Definition Epinephrine in a concentration of 0.02 mg/kg (approximately 1.0 mg in adults) is given for cardiovascular collapse, asystole, ventricular fibrillation, electromechanical dissociation, or anaphylactic shock. The larger dose range is recommended in these critical situations to maintain myocardial and cerebral perfusion through peripheral vasoconstriction. This vascoconstriction increases aortic diastolic blood pressure, which promotes coronary […]
Definition Dantrolene is a hydantoin derivative used as a muscle relaxant that acts by reducing calcium release from the sarcoplasmic reticulum, effectively abolishing excitation-contraction coupling in muscle cells. Due to its ability to reduce intracellular calcium levels, dantrolene is a specific and effective agent in the treatment of malignant hyperthermia. Verapamil, a calcium channel blocker, […]
Definition The quotient of exhaled CO2 (VeCO2) and arterial CO2 (Ve/PaCO2) is a measure of the ventilatory response to hypoxia. The difference between exhaled CO2 (VeCO2) and arterial CO2 (PaCO2-VeCO2) is a measure of physiologic dead space VeCO2 and PaCO2 VeCO2/PaCO2: measure of ventilatory response to hypoxia PaCO2 – VeCO2: measure of dead space […]
Definition Ventricular Pressure Volume Loop This left ventricular pressure volume (P-V) loop shows two loops superimposed on one graph. The grey loop represents the control or normal P-V loop and the pink loop represents a P-V loop with increased inotropy. This image was taken from the wikicommons site. It has been labeled further with numbers […]
Definition Both the right and left ventricles can increase in size when subjected to chronic abnormal stress. When the stress is pressure overload, sarcomeres replicate in parallel, resulting in concentric hypertrophy. This is seen as increased wall thickness. When the stress is volume overload, sarcomeres replicate in series, resulting in eccentric hypertrophy. This is seem […]
Definition General anesthesia causes an increase in intrapulmonary shunt, which may impair oxygenation, and the magnitude of shunt is correlated with the formation of atelectasis. The atelectasis appears within minutes after anesthesia induction in nearly 90% of patients. The degree of atelectasis is larger with obese patients and when a higher fraction of inspired oxygen […]
Definition Ventilator associated pneumonia (VAP), once diagnosed in critically ill patients, should be managed with prompt initiation of broad spectrum antibiotic coverage (this is based on extrapolation of data from septic patients which shows a direct correlation between mortality and time to initiation of appropriate antibiotic coverage (Ref. 1) followed by a reasonable attempt at […]
Definition In volume control modes, the change (slope) of the airway pressure waveform decreases as more volume enters the lungs (an resistance to inflow) decreases. By contrast, in pressure control modes, pressure is constant across each breath (and the slope of the flow waveform changes throughout the ventilatory cycle). Subspecialty General Related Media Keyword history […]
Definition Incidence As high as 76% (by TEE) or 40% by precordial Doppler (less sensitive than TEE) in patients undergoing posterior fossa procedures in the sitting position. Incidence is lower in p-fossa procedures not in the sitting position. Even lower but still possible in cervical laminectomy. Most commonly in tumors near the posterior saggital sinus. […]
Definition Diabetes insipidus is due to either inability to produce ADH or kidney not responding to ADH. DI results in polyuria with increased serum osmolarity. Pre-op treatment includes replacing daily fluid loss, nasal administration of DDAVP (Desmopressin), or IV ADH (Vasopressin) w/ infusion allowing daily break-through polyuria. Measure serum Osms hourly, if > 290 give […]
Definition Hepatic and renal and renal metabolism, renal excretion, elimination half time 10-20 mins. Vasopressin (arginine vasopressin, AVP; antidiuretic hormone, ADH) is a nonapeptide hormone formed in the hypothalamus and released from the posterior pituitary. Its primary function in the body is to regulate extracellular fluid volume by affecting renal handling of water; however, it […]
Definition In calculating vaporizer output, you must consider three flow streams – “vaporizer inflow,” the volume of fresh gas diverted into the vaporizing chamber, per minute, “diluent flow,” the volume of fresh gas diverted around the vaporizing chamber, per minute, and “vapor outflow.” Application of the principle of conservation of mass to these three flow […]
Definition The definition of MAC is the concentration of the vapor (measured as a percentage at 1 atmosphere, i.e the partial pressure) that prevents the reaction to a standard surgical stimulus in 50% of subjects. Since most of us work at about 1 atmosphere, we can still think in terms of % concentration, but what […]
Definition Definition of vapor pressure: In a closed container, molecules from a volatile liquid escape the liquid phase and become vapor. These gaseous molecules strike the wall of the container, exerting what’s known as vapor pressure. Vapor pressure is directly correlated with temperature. Increasing temperature will increase the ratio of gas:liquid molecules, thereby increasing vapor […]
Definition All volatile halogenated agents cause dose-related relaxation of the uterus which may lead to increased blood loss during cesarean section. From induction to delivery of the infant 1.0 MAC is given to avoid maternal awareness. After delivery, volatile anesthetics are decreased to 0.5 – 0.75 MAC and oxytocin is given concurrently to decrease the […]
Definition Rationale: manual removal of a retained placenta breech delivery: obstructed after coming head or shoulders multiple pregnancy: second twin in transverse-lie inadvertent oxytocic overdose prior to delivery uterine constriction ring inverted uterus (some cases of) fetal distress. Agents used: inhalationed agents, nitrates (IV NTG:50mcg/ml. With NTG, uterine relaxation should be achievable in 75 to […]
Definition Most common cause of postpartum hemorrhage. Treated with synthetic oxytocins (ex. oxytocin injection, Pitocin®), which do NOT contain vasopressin – if given rapidly (ex. 10 U Pitocin® rapidly, despite that the manufacture recommends only 5 U slowly), these agents can cause vasodilation/hypotension and tachycardia [Pinder AJ et al. Int J Obstetr Anesth 11: 156, […]
Definition The effect of V/Q mismatching on uptake of volatile anesthetics is dependent on the solubility of the anesthetic agent. Using endobronchial intubation as an example – for relatively insoluble agents (ex. desflurane [blood gas solubility coefficient 0.42, MAC 6-7.3%]), the rate of rise of arterial partial pressure of agent is slower for a given […]
Definition Infant’s Physiology Pediatric intravascular and extracellular fluid compartments are relatively larger than adults Hepatic biotransformation pathways are immature in neonates and young infants Protein binding is decreased Metabolic rate is higher than adults Infants have proportionately higher total body water than adults (70-75% vs. 50-60%) secondary to relatively higher fat content and smaller muscle […]
Definition Theories concerning the etiology of tourniquet trelated pain have identified nerve ischemia and compression as the main sources of noxious stimuli during the maintenance of tourniquet inflation. Unmyelinated C fibers, whose function is preserved during prolonged tourniquet inflation, have been recognized to represent an important nociceptive pain pathway. Increase in C fiber action potential […]
Definition Introduction Orthopedic procedures in the arm may be performed under a variety of brachial plexus blocks, with intravenous regional anesthesia, or by using combinations of individual nerve blocks in the arm. The selection of a particular technique depends on the need for a tourniquet and on the site of anticipated surgery. Shoulder Surgery The […]
Anatomy The brachial plexus derives from nerve roots from C5 to T1 with minor or absent contribution from C4 and T2. These roots emerge from their intervertbral foramina and travel between the anterior and middle scalene muscles where they form 3 trunks (upper, middle and lower). As the trunks pass over the first rib and […]
Definition The upper airway consists of the pharynx and the nasal cavities; however, some authors include the larynx and trachea as well. The pharynx is can be divided into the nasopharynx, oropharynx, and laryngopharynx. The nose is composed of bone and cartilage, which are in turn attached to the facial skeleton. It is a pyramidal […]
Definition Postoperative blindness is a devastating and fortunately rare complication of general anesthesia. The incidence of postoperative blindness is low (Ref. 1). In one retrospective study, only one out of 60965 patients suffered permanent loss of vision. (Ref. 2) Post-operative visual loss typically occurs as an ischemic sequelae of external compression of the globe, hypotension, anemia […]
Definition The ideal leak pressure for an uncuffed ETT is 20-30 cm H2O. Remember that a cuffed ETT should be 1/2 size smaller than an uncuffed ETT. If 40 cm H20 or more must be applied to generate a leak, remove the ETT and replace it with something smaller. Uncuffed ETT are generally used on […]
Definition Echogenicity is a measure of acoustic reflectance, i.e. the ability of a tissue to reflect an ultrasound wave. The source of echogenicity is impedance mismatching between tissues. Impedance can be thought of as resistance to flow of mass or energy from a pulsatile source (unlike resistance, which generally assumes a steady source of mass […]
Definition Acoustic impedance is the resistance to sound wave propogation. The denser the material, the more acoustic impedance it has; the more echogenic it is, the more white it appears on our screen. Subspecialty General Related Media Keyword history 82%/2011 See Also: Sources PubMed
Definition When posing a question to be studied, the null hypothesis is the hypothesis that there is no difference between two populations. Wrongly rejecting the null hypothesis, or stating that there is a statistically significant difference in the data when in fact there is not (false positive), is called type I error or alpha error. […]
Definition The type and screen determines both the ABO-Rh of the patient and screens for the presence of the most commonly found unexpected antibodies. Type ABO-RH testing (the “Type”): The patient’s blood cells are mixed with serum known to have antibodies against A and against B to determine blood type. The patient’s blood cells are […]
Definition Fluid restriction Loop diuretics Hypertonic saline no faster than 100cc/hr for symptomatic hyponatremia Midazolam or phenytoin for seizure activity Intubation for airway protection Subspecialty General Related Media Keyword history 90%/2012 54%/2010 See Also: TURP – Irrigating fluid complications TURP solutions – Neuro complications Sources PubMed
Definition Introduction and Controversy Introduction to Liposuction and Tumescent Fluid Howard Solbel, in an editor’s response to Yoho’s article (see below), state the following – “Let us first understand the difference between the tumescent technique and the tumescent solution. The tumescent technique involves using the tumescent solution (lidocaine 0.05%, epinephrine 1:1,000,000) anywhere from 1:1 up […]
Definition Introduction and Controversy Introduction to Liposuction and Tumescent Fluid Howard Solbel, in an editor’s response to Yoho’s article (see below), state the following – “Let us first understand the difference between the tumescent technique and the tumescent solution. The tumescent technique involves using the tumescent solution (lidocaine 0.05%, epinephrine 1:1,000,000) anywhere from 1:1 up […]
Definition Tumescent anesthesia is a technique commonly used in cosmetic and dermatologic procedures. It involves subcutaneous infiltration of large volumes of tumescent fluid containing lidocaine (0.05% or 0.1%), saline, and epinephrine (1:1,000,000) to produce anesthesia, swelling, and firmness of targeted areas. Maximum safe dosage is estimated to be 35-55mg/kg of lidocaine. This technique is most […]
Definition Trigeminal neuralgia or (tic dolereaux) is characterized by intense, stabbing pain in the distribution of the trigeminal nerve. The trigeminal nerve is mostly a sensory nerve its only motor function being the muscles of masctication. It is divided into the ophthalmic, maxillary and mandibular divisions. The three divisions join and form the Gasserion ganglion […]
Definition Mechanisms of morbidity: vascular injury leading to extradural hematoma (rapid expansion high mortality 20%), cortical bridging veins leading to subdural hematoma (slow expansion). Either mechanism leads to elevated ICP and decreased arterial inflow resulting in reduced cerebral perfusion pressure -> tissue hypoxia and cell death. TBI can result in loss of autoregulation. SAH is […]
Definition TRALI most common cause of transfusion related mortality (Miller, 7th ed). Acute hemolytic reaction Definition: When antibodies to a particular blood antigen already exist. Can be delayed if there is an amnestic response to a transfused RBC antigen to which the recipient is already sensitized. Causes: Usually the result of ABO incompatibility and technical […]
Definition Transfusion transmitted bacterial infection (TTBI) is an important complication of blood product administration. A wide spectrum of organisms has been associated with transfusion transmitted bacterial infection, including skin, enteric, and environmental organisms. Gram-negative rods have been observed more frequently as red blood cell contaminants, while gram-positive organisms have been observed more frequently as platelet […]
Definition Indicated for chronic pain in opioid tolerant patient who is unable to tolerate enteral opioid medications. Often prescribed with something else for breakthrough pain. Not for mild, moderate, or short-term pain relief. Avoid heat which could release more drug than intended. Subspecialty Pain and Regional Anesthesia Related Media Keyword history 93%/2012 93%/2009 See Also: […]
Definition Transcutaneous Pacing (TCP) is a temporary means of pacing a patient’s heart during an emergency and stabilizing the patient until a more permanent means of pacing is achieved. It is accomplished by delivering pulses of electric current through the patient’s chest, stimulating the heart to contract. The most common indication for TCP is symptomatic […]
Definition Transcutaneous Pacing (TCP) is a temporary means of pacing a patient’s heart during an emergency and stabilizing the patient until a more permanent means of pacing is achieved. It is accomplished by delivering pulses of electric current through the patient’s chest, stimulating the heart to contract. The most common indication for TCP is symptomatic […]
Definition What is TRALI? Noncardiogenic pulmonary edema, 5% mortality Plasma containing blood products (Plt and FFP >>> pRBCs) Reaction b/w donor anti-HLA or antileukocyte Ab’s & recipient leukocytes sequestration in microcirculation of lungs capillary endothelial damage/leak. Diagnosis: Acute onset of hypoxemia (within 6 hrs of transfusion) Bilateral CXR infiltrates c/w ALI Normal LA pressures (<18mmHg) […]
Definition TRALI: a inflammatory (non-hydrostatic) pulmonary edema Characterized by: acute respiratory distress hypoxemia hypotension fever widespread pulmonary infiltrates The majority of cases occur within minutes Most are within 1-2 hours, but must be <6 hours after blood product transfusions to qualify as TRALI Happens in 1/5000 blood product transfusions […]
Definition Bilateral pulmonary edema unassociated with heart failure, bilateral patchy infiltrates may proceed to complete white out Indistinguishable from ARDS Subspecialty General Related Media Keyword history 74%/2012 See Also: Sources PubMed
Definition Respiratory quotient is the ratio of VCO2 and VO2 (carbon dioxide production). In other words: RQ = CO2 eliminated/O2 consumed. It is used in calculations of basal metabolic rate (BMR). Under typical metabolic conditions with stable respiratory function, the range of RQ in human metabolism is approximately 0.7 to 1.0. A value of 1.0 […]
Definition TPN is usually slowed or discontinued prior to anesthesia, primarily to avoid complications from excessive (hyperosmolarity) or rapid decrease (hypoglycemia) in infusion rates in the busy operative arena. That said, because abrupt discontinuance may lead to severe hypoglycemia, TPN must be turned down gradually. According to Miller (Chapter 35), Dr. Michael F. Roizen has […]
Definition Paralysis of the joint being operated on is important for placement of a prosthesis and passive ROM, so spinals or epidurals are typical choices for regional anesthestia in total knee arthroplasties. Although both are appropriate techniques, your choice could be based on the patient’s age, as younger patient’s have a higher risk of spinal […]
Definition Centers for Medicare & Medicaid Services: For anesthesia services furnished on or after January 1, 1994, the A/B MAC computes time units by dividing reported anesthesia time by 15 minutes. Subspecialty General Related Media Keyword history 85%/2014 76%/2011 See Also: Sources Medicare Claims Processing Manual (Section 50 G) PubMed
Definition For a volatile anesthetic agent, the time constant (τ) is volume divided by flow. From the standpoint of the anesthesia circuit, the time constant is the volume of the circuit divided by the fresh gas flow rate (units of L divided by L/min results in min). From the standpoint of the lungs, the time […]
Definition Major postoperative complications include wound infection, bleeding, airway obstruction (compressing hematoma, tracheomalacia), hypocalcemia, thyroid storm (uncommon, usually associated with Grave’s disease) and recurrent laryngeal nerve injury. 1) Hypocalcemia Incidence is 3-5%. Surgery can lead to trauma to the parathyroids, devascularization of the glands with resultant ischemia, or inadvertent excision of these small structures. Hypoparathyroidism […]
Definition Hypoxemia during a thoracoscopic procedure with one-lung ventilation (OLV) is a common problem that needs to be dealt with by the anesthesia provider. Hypoxemia is commonly defined as oxygen saturation < 90% (Pao2 > 60 mm Hg). The basic goal during OLV is to maximize pulmonary vascular resistance (PVR) in the nonventilated lung while […]
Definition Barbiturate coma therapy has been used in head injured patients to lower ICP when other therapies such as mannitol and hyperventilation have failed. Barbiturates may also protective during periods of cerebral hypoxia. The mechanism of action of barbiturates is by inhibiting the synaptic transmission thereby decreasing the cerebral metabolic rate of oxygen consumption, reducing […]
Definition The primary mechanism for termination of action of thiopental (Pentothal) and methohexital (Brevital) is redistribution from the brain to other inactive compartments (i.e. skeletal muscle, fat). This mechanism is distinct from metabolism as a means of terminating anesthetic effect. Subspecialty General Related Media Keyword history 95%/2011 See Also: Sources PubMed
Definition Thiopental (or another barbiturate) administration titrated to EEG suppression causes a decrease in the cerebral metabolic rate of O2 (CMRO2) as well as a decrease in cerebral blood flow (CBF) due to flow-metabolism coupling. At general anesthetic doses, the CBF and CMRO2 are reduced by ~ 30%, whereas with EEG suppression they are maximally […]
Definition Tetrology of Fallot usually consists of right ventricular obstruction, right ventricular hypertrophy, and a VSD with an over-riding aorta. The right ventricular obstruction is usually secondary to hypertrophy of the subpulmonic muscle. Up to 25% of patients also have pulmonic stenosis. The infundibular obstruction dynamic and can be increased secondary to sympathetic tone, this […]
Definition The primary physiologic goal when managing a tetralogy spell (cyanosis following a sudden increase in PVR) is reducing the right-to-left shunt (through the VSD), i.e. re-directing blood through the lungs. Pharmacologic management of tetralogy spells include β-blockade, alpha-agonism (increases both PVR and SVR, however if PVR is already elevated, does not have an additional […]
Definition Classic signs include decreased breath sounds, distended neck veins, and non-midline trachea. These are VERY uncommon. More common changes suggestive of tension pneumothorax include hypotension, tachycardia, narrowing pulse pressure, and oxygen desaturation. Under anesthesia, these patients may exhibit a rise in airway pressures. Awake, they may become tachypnic. In the setting of hemodynamic instability, […]
Definition TENS (transcutaneous electrical nerve stimulation) produces analgesia via stimulation of large afferent fibers. This is generally used for mild-moderate acute pain and chronic pain such as low back pain, arthritis, and neuropathic pain. Theories: Gate Theory: afferent input from large epicritic fibers competes out input from small pain fibers. Conduction block theory: high […]
Definition Overview: Thromboelastography and the resulting thromboelastograph (TEG) provide point of care testing of the coagulation cascade, platelet function, platelet-fibrin interaction, and fibrinolysis. Technique: Whole blood is placed in a cuvette and a pin and torsion wire mechanism applied while the cuvette oscillates and the blood clots. A recording of the signal from the torsion […]
Definition Other Congenital anomalies associated with tracheoesophageal fistula (TEF) include VATER and VACTERL associations. VACTREL V – Vertebral anomalies A – Anal atresia C – Cardiovascular anomalies T – Tracheoesophageal fistula E – Esophageal atresia R – Renal (Kidney) and/or radial anomalies L – Limb defects VACTERL – VATER + C, cardiac, L, limb anomalies […]
Definition TEE and Perfusion Distribution TEE is an evaluation of Ventricular functions and has been crucial in the OR – goal of intraoperative ventricular function monitoring provides: Goals of Ventricular Function Monitoring continuous global function assessment volume status information regional function assessment as a reflection of acute coronary ischemia left atrial pressure estimation In concentrating […]
Definition TEE is an evaluation of Ventricular functions and has been crucial in the OR – goal of intraoperative ventricular function monitoring provides: Goals of Ventricular Function Monitoring continuous global function assessment volume status information regional function assessment as a reflection of acute coronary ischemia left atrial pressure estimation In concentrating on TEE’s role in […]
Definition TEE may be the most useful diagnostic modality in sudden, life-threatening hypotension. Hypotension is ALWAYS caused by either decreased cardiac function, decreased afterload, or a combination of both. TEE is capable of helping differentiate the two – hypotension predominantly due to decreased afterload will manifest as a hypercontractile ventricle. Hypotension predominantly due to decreased […]
Definition A tracheo-esophageal fistula (TEF) is a congenital defect that is thought to be a result of a foregut malformation of uncertain etiology around the 4th to 5th week of gestation age. This malformation can be present in various anatomic formations and are categorized as Type A-E. Ninety-percent of TEFs are Type C, which consists […]
Definition Central Nervous System (CNS) Induction doses of ketamine are generally considered to increase cerebral blood flow (CBF), cerebral metabolism (CMRO2), and intracranial pressure (ICP); however, there is evidence that ketamine administered to anesthetized and mechanically ventilated patients does not increase ICP and has little impact on cerebral hemodynamics. For example, ketamine, in doses up […]
Definition Synchronized cardioversion is employed for hemodynamically unstable supraventricular tachycardias (atrial fibrillation / atrial flutter, AV junctional tachycardia, multifocal atrial tachycardia, and paroxysmal reentrant tachycardia). New onset atrial flutter often requires only 50 J (monophasic or biphasic). For atrial fibrillation and PSVT in adults start with 100-120 J for biphasic waveforms (100-200 J with monophasic). […]
Definition The sweat glands are innervated by the sympathetic nervous system and are part of the fight or flight response system. Their innervation consists of two parts, a preganglionic and postganglionic neuron. The preganglionic neuron is short, originates from the thoracolumbar region of the spinal cord, uses acetylcholine as its neurotransmitter, and synapses with the […]
Definition SvO2 monitoring provides information about the overall balance between oxygen supply and demand; however, does not reflect oxygenation in individual organs. Continous monitoring is accomplished via an oximetric pulmonary artery catheter (PAC). SvO2 = SaO2 – Subspecialty Cardiac Anesthesia Related Media Keyword history 85%/2012 80%/2009 See Also: Sources PubMed
Definition After the administration of succinylcholine, an 0.5 – 1.0 mEq/mL increase in serum potassium is normal. Patients with neuromuscular disease such as a stroke have risk of serious hyperkalemia after succinylcholine. This usually peaks 7-10 days after insult, but increased K+ release may occur as soon as 2-4 days after denervation injury, or after […]
Definition As many as 2% of pregnant women undergo anesthesia for non-obstetric surgery. Routine pregnancy testing should be mandatory for all women of child-bearing age. Note that organogenesis occurs from 15-56 days of gestation. Early concerns for the pregnant patient revolve around the potential for altered organogenesis, but as the fetus matures concerns shift towards […]
Definition SLN: a branch of the vagus nerve (CN X), innervates key areas of the airway. Internal branch: Originates lateral to cornu of hyoid bone, pierces thyrohyoid membrane, travels under mucosa in pyriform recess Sensory innervation: base of tongue, epiglottis, aryepiglottic folds, arytenoids External Branch: Motor innervation: cricothyroid muscle (tensor muscle) Blocking SLN: Topical application […]
Definition Normal muscle releases enough potassium during succinylcholine-induced depolarization to raise serum potassium by ~ 0.5 mEq/L. Although this is usually insignificant in patients with normal baseline potassium levels, it can be life-threatening in patients with preexisting hyperkalemia or those with burn injury, massive trauma, neurological disorders/spinal cord injury (as well as in tetanus, prolonged […]
Definition Classic teaching espouses that fasciculations in the abdominal wall muscles cause a transient increase in gastric pressure, which is offset by a concurrent increase in SCh-induced LES tone. More recent animal studies have suggested that the changes in both intragastric and LES pressure are trivial and not statistically significant ramide in premedication for or […]
Definition Should be avoided due to a significant risk of hyperkalemia. Ferguson et al described four patients with chronic/relapsing polyneuropathy who developed life-threatening arrhythmias following succinylcholine administration, although in this instance SCh was presumed, but not documented to be the cause (1). Reilly and Hutchinson described a case (2) in which a 51-year-old man developed […]
Definition The initial metabolite of succinylcholine (SCh), succinylmonocholine, produces a tranisent negative chronotropic effect through its stimulation of sinus node muscarinic receptors. Repeated dosing or infusions of SCh may lead to bradycardia that is appropriately treated with atropine. Subspecialty General Related Media Keyword history 91%/2009 See Also: Sources PubMed I Yasuda, T Hirano, K […]
Definition Classic teaching espouses that fasciculations in the abdominal wall muscles cause a transient increase in gastric pressure, which is offset by a concurrent increase in SCh-induced LES tone. More recent animal studies have suggested that the changes in both intragastric and LES pressure are trivial and not statistically significant ramide in premedication for or […]
Definition Subdurals happen in the potential (or traumatically created, there is no consensus to what truly happens) space between the dura and the arachnoid. Radiologists find this space occasionally under fluoroscopy and note that when fluid is injected here it ascends against gravity. Secondly, once it is found (or created) it probably becomes a permanent […]
Definition SAH: refers to extravasation of blood into the subarachnoid space between the pial and arachnoid membranes. SAH comprises half of spontaneous atraumatic intracranial hemorrhages, the other half consist of bleeding that occurs within the brain parenchyma. Intracranial hemorrhage as a whole comprises 20% of all strokes. High morbidity and mortality, usually associated with head […]
Definition Evidence from a number of studies indicates that patients with SAH are at high risk for malignant ventricular arrhythmias, including ventricular tachycardia, torsades de pointes, and ventricular fibrillation, particularly if the corrected QT (QTc) interval is prolonged. A decrease in cardiac output due to alterations in cardiac rate associated with SAH, such as sinus […]
Definition The sub-ambient pressure alarm is intended to identify a breathing system pressure of <-10 cmH2O. Common causes of negative pressure include spontaneous respiration by the patient with an obstruction in the circuit, scavenging system problems, or application of a suction device into the circuit (suction catheter in the endotracheal tube). This alarm would function […]
Also called masking, it’s a tool to reduce bias by preventing researchers and/or subjects from knowing what is going on. You can be blinded to the hypothesis, the case-control classification, the assignments or treatments. Without blinding, humans tend to inadvertently corrupt studies with asymmetric measurements and assessments. Single-blinded refers to the subject being in the […]
Definition Atrial fibrillation and loss of “atrial kick” leads to a decrease in stroke volume due to decreased in left ventricular end-diastolic volume (preload). This effect is especially severe in diastolic dysfunction, impaired contraction, or in mitral stenosis. The contribution to ventricular filling is about 10% at rest but increases to up to 40% with […]
Definition Also called a cervicothoracic sympathetic block and used primarily to treat Complex Regional Pain Syndrome. It has also been used to treat refractory angina, phantom limb pain and vascular insufficiency (such as Raynaud’s or frostbite), hyperhydrosis and other things. The stellate ganglion is formed by the fusion of the inferior cervical and first thoracic […]
Definition First, it is important to think about what are proportions and what variables are being evaluated with these tests. Proportions include the incidence of something and these tests evaluate categorical variables. These are variables that you cannot put a bell curve through. This is different from tests of means which compares the means of […]
Definition According to Wikipedia, the median is “the numeric value separating the higher half of a sample, a population, or a probability distribution, from the lower half.” Its advantage over the mean is that it is relatively resistant to outliers. Keyword history 89%/2009 Sources Median, Wikipedia.org
Definition ANOVA test is used to compare the means (average) +/- SD for more than two groups (normally distributed). If only two groups then can use a t-test. Paired t-test takes multiple measures and compares the differences. In this test each subject serves as their own control. Used w/ ladder plots, usually in crossover studies. […]
Definition There is a growing body of animal data to suggest that statins may be helpful in treating septic patients. Data in humans, for the most part, are lacking. In a prospective observational cohort study it was found that prior statin therapy is associated with a decreased rate of severe sepsis and ICU admission in […]
Definition Sensory Evoked Potentials (SEPs) Described in terms of site of origin (stimulus), latency, and amplitude. SSEPs Generally originate near the median/ulnar nerves or posterior tibials. Recording electrodes are on the scalp or spinal cord. Note that volatile anesthetics increase SSEP latency and decrease SSEP amplitude – nitrous oxide decreases SSEP amplitude but does not […]
Definition Inhalational anesthetics (halogenated anesthetics and nitrous oxide) decrease the amplitudes and increase the latency of SSEPs in a dose-dependent manner. (1) Midazolam has little effect below 150mcg/kg. Propofol has minimal effects between 120-200mcg/kg/min Ketamine and Etomidate are acceptable as well. (2) Opioids have minimal effects on SSEPs or MEPs. At higher doses: (3) Etomidate increasesboth […]
Definition See Abstract in Barker et al reference below. Subspecialty General Related Media Keyword history 88%/2012 See Also: Sources PubMed Barker SJ, Tremper KK, Hyatt J. Effects of methemoglobinemia on pulse oximetry and mixed venous oximetry. Anesthesiology. 1989 Jan;70(1):112-7.
Definition Etiology: Degeneration of the nucleus pulposis and reduction of disk height over time leading to osteophyte formation which can then cause progressive narrowing of the intervertebral foramina and spinal canal. Definition: When osteophyte formations compress multiple nerve roots and cause bilateral pain and/or encroach on the cauda equina. Symptoms: Back pain that usually radiates […]
Definition A spinal cord stimulator (SCS) is a device used to exert pulsed electrical signals to the spinal cord to control chronic pain. SCS consists of stimulating electrodes, implanted in the epidural space, an electrical pulse generator, implanted in the lower abdominal area or gluteal region, conducting wires connecting the electrodes to the generator, and […]
Definition “The blood supply to the spinal cord depends on a single anterior spinal artery and bilateral posterior spinal arteries. The arteries arise from the circle of Willis and receive reinforcements during their descent in the spinal canal. The posterior spinal arteries receive regular contributions from radicular arteries, but the single anterior spinal artery, which […]
Definition Anatomical Points Conus medullaris terminates at L1 in the adult (L3 in the newborn), after which the SC is referred to as the cauda equina (L2 – sacral) Tracts Ascending Dorsal Column/Medial Lemniscus Tactile, vibration, proprioception. Located dorsally. First order neurons located in DRG. Travel on same side as DRG and cross over in […]
Definition Compared to adults, pediatric patients have very little hemodynamic derangement with spinal anesthetics. This holds true for children from the neonatal period through around age 5 (Lopez, 2012). Position of the dural sac varies in children and adults. It is generally believed that the dural sac extends more caudally in children (S3) than its […]
Definition Lidocaine was first used as a spinal anesthetic in 1948. In 1991, case reports of cauda equina syndrome began to appear following the use of 5% lidocaine through microcatheters. Two years later, in 1993, transient neurologic symptoms (TNS), was described. TNS is a painful condition of the buttocks and thighs with possible radiation to […]
Definition Although a Cochrane Database Review suggests that there is no advantage of spinal over GA for premature or former premature infants undergoing inguinal hernia repair [Craven PD et al. Cochrane Database Syst Rev. CD003669, 2003], spinals are still often used by pediatric anesthesiologists for “high risk” patients. Most neonates who get spinals are either […]
Definition Most important factors: Baricity of anesthetic solution (relative to CSF) Hyperbaric (glucose added) – follows gravity, greater cephalad spread, normal dependent portion of spine in supine position is T4-T8 Hypobaric (dilute with sterile water) – spreads in nondependent fashion Isobaric- behave clinically as slightly hyperbaric Patient positioning (during and immediately after injection) Drug dosage […]
Definition The most common indication for spinal anesthesia in pediatric patients is its use in former preterm infants undergoing bilateral inguinal hernia repairs. Apnea can occur in former preterm patients following a general anesthetic. A number of small studies have confirmed this finding however, there is considerable disagreement regarding the incidence of apnea and the […]
Definition According to Miller, Figure 59-52, the paramedian approach to the epidural space is now favored by most anesthesiologists at the midthoracic levels. The needle is inserted 1 cm lateral to the superior tip of the spinous process and then advanced perpendicular to all planes to contact the lamina of the vertebral body immediately below. […]
Definition Smoking and P50 Smoking is a major risk factor associated with perioperative respiratory and cardiovascular complications. Evidence also suggests that cigarette smoking causes imbalance in the prostaglandins and promotes vasoconstriction and excessive platelet aggregation. Two of the constituents of cigarette smoke, nicotine and carbon monoxide, have adverse cardiovascular effects. Carbon monoxide increases the incidence […]
Definition In the first 48-72 hours quitters may have increased secretions and more reactive airways. Acute cessation decreases carboxyhemoglobin and increases oxygenation to tissues (right shift of oxyhemoglobin curve), less carbon monoxide, less nicotine and associated tachycardia, and increased ciliary function. Other benefits take 2-4 weeks, such as decreased secretions and decreased airway reactivity. 4-6 […]
Definition Perfusion pressure of a tissue in reference to a blood pressure taken at another site is dependent on the elevation difference between the two sites. The conversion from the cm of elevation difference between the two sites and the mm of Hg of pressure is not linear. Instead, 1.36 cm H2O = 1 mm […]
Definition Beta-Adrenergic receptor-agonists (Terbutaline) Ritodrine is the only FDA approved medication in this class, but (ironically) isn’t available in the US. Thus, terbutaline is frequently used for this indication. Beta-agonists relax smooth muscles, including the myometrium. Binding of the receptor increases intracellular levels of cyclic AMP. This increase in intracellular levels of cyclic AMP activates […]
Definition Antidiuretic hormone (ADH) is synthesized in the supraoptic and periventricular nuclei of the hypothalamus and transported to the posterior pituitary by the hypothalamoneurohypophyseal tract. ADH is released by the posterior pituitary and serves to regulate the osmolarity of body fluids. In the kidney, ADH opens aquaporins in the distal and collecting tubules (in a […]
Definition Septic shock is the most common type of vasodilatory shock and leading cause of mortality in the United States. Currently cardiovascular support involves fluid administration, use of catecholamines, and potentially the use of inotropes, corticosteroids, or vasopressin. Vasopressin is an endogenous hormone essential for both osmotic and cardiovascular homeostasis synthesized in the hypothalamus and […]
Definition Toll-like receptors are stimulated by bacteria, viruses, fungi, protozoa, and activate NF-kB and NJK, which begin the transcription and production of cytokines Mediators of Stress Response in Sepsis TNF-alpha (gram negative)IL-1 and IL-6 (gram negative), IL-8 (gram positive) Subspecialty General Related Media Keyword history 55%/2008 See Also: Sources Miller’s Anesthesia, 7th Edition. Chapter 95 […]
Definition Septic Shock = Vasidilatory Shock characterized by a low afterload state in which organ perfusion is impaired. Mechanisms: Systemic venodilation from increased nitric oxide levels Decreased circulating intravascular volume from a diffuse capillary leak and the resulting transudation of fluid into tissues, producing a relative hypovolemia. Myocardial depression There are many mechanisms for diffuse […]
Definition A sentinel event is an unexpected occurrence involving death or serious physical or psychological injury or the risk thereof. Subspecialty General Related Media Keyword History 87%/2015 85%/2012
Definition Oral decontamination (2% gentamicin, 2% colstin, and 2% vancomycin paste) has been shown to reduce pneumonia and mortality in ventilator dependent patients without an increased incidence of antibiotic resistance [Am J Respir Crit Care Med 164: 382, 2001; Crit Care Med 32: 126, 2004]. The CDC still does not recommend oral decontamination routinely [CDC […]
Definition Epidemiology and Risk Factors Secondary generalized seizures are the most common type seen in the ICU [Neurosurg Clin Am 4: 327, 1993]. Post-traumatic seizures are also common, either in or out of the ICU – almost 10% of the 400,000 patients treated for head injury will suffer either an early or late seizure [Neurology […]
Definition Standard deviation (SD) is used to figure out how “spread out” a data set is. Standard error (SE) or Standard Error of the Mean (SEM) is used to estimate a population’s mean. For example if you have a large population, then different samples drawn from that same population would in general have different values […]
Definition The 1997 guidelines were revised in 2008. They are summarized here: http://www.chp.edu/CHP/Antibiotic+Guidelines Subspecialty Cardiac Anesthesia,General Related Media Keyword history 94%/2014 82%/2011 See Also: Sources PubMed Wilson et al. Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on […]
Definition AHA revised guidelines for endocarditis prophylaxis in 2007. Cardiac lesions are classified into low, moderate and high risk for developing endocarditis. Antibiotic prophylaxis is recommended for moderate and high risk lesions. Low risk lesions are considered to be negligible consequence therefore antibiotic prophylaxis is not recommended. Summary of AHA guidelines: Infective endocarditis is an […]
Definition The saphenous nerve is a terminal cutaneous branch of the femoral nerve. It is commonly blocked to complement anesthesia of the lower leg. It is strictly a sensory nerve; it has no motor component. The saphenous innervates the skin over the medial, anteromedial, and posteromedial aspect of the lower leg from knee to ankle. […]
Definition Transducer characteristics, such as frequency and shape, determine ultrasound image quality. Ultrasound waves have frequencies that exceed the upper limit for audible human hearing, i.e., greater than 20 kHz. Medical ultrasound devices use sound waves in the range of 1–20 MHz. Proper selection of transducer frequency is an important concept for providing optimal image […]
Definition Root cause analysis (RCA) is a method of problem solving that is aimed at identifying the root causes of problems or incidents. It is based on the belief that problems are best solved by trying to correct or eliminate root causes and by directing corrective measures at these causes in hopes that the recurrence […]
Definition Previous hernia surgery Previous abdominal surgery Previous prostate surgery Subspecialty General Related Media Keyword history 66%/2009 See Also: Sources Faulkner Hospital In Massachusetts PubMed
Definition Mechamism of Action Ritodrine is a selective beta-2 receptor agonist that developed specifically for use as a uterine relaxant. Ritodrine suppress premature uterine contractions through their effects on increase in intracellular cyclic adenosine monophosphate (cAMP) and relaxes uterine smooth muscles. Intended Use Uterine Relaxant Side Effects Cardiac Effects (Tachycardia) Tachycardia is a common adverse […]
Definition Rheumatoid arthritis (RA) affects ~ 1% of adults. Importantly, RA is is a systemic disease, affecting the skeletal system as well as the cardiac and pulmonary systems and often leading to a vasculitis. Patients on DMDs are at increased risk for infection. Diagnosis is primarily clinical and notable for morning stiffness and metacarpophalangeal involvement […]
Definition Rheumatoid arthritis is the most common chronic inflammatory arthritis affecting roughly 1% of adults with a predilection for females. The disease is characterized by symmetrical polyarthropathy and significant systemic involvement. Signs and Symptoms of RA: Joint Involvement: hands, wrists, knees, temporomandibular joint, cervical spine (atlantoaxial subluxation, odontoid process may compress the spinal cord). Systemic […]
Definition Surgery involving the cornea, anterior chamber, and lens can be performed with a retrobulbar or peribulbar block. Retrobulbar Block Retrobulbar block involves depositing local anesthetic inside the muscle cone. It aims to block the ciliary nerves, the ciliary ganglion, and cranial nerves III, IV, and VI. The ciliary ganglion is a parasympathetic ganglion, which […]
Definition Background Respiratory distress syndrome is caused by a deficiency of surfactant, a phospholipid responsible for stabilizing alveolar surfaces and reducing surface tension. Surfactant is 70% lipid (phosphatidylcholine) combined with proteins. When surfactant is deficient, it is more difficult to generate the inspiratory pressure needed to inflate alveoli, resulting in progressive atelectasis. In addition, surfactant […]
Respiratory alkalosis is due to increased alveolar ventilation relative to carbon dioxide production. Acute hypocapnia causes a reduction of serum levels of potassium and phosphate secondary to increased cellular uptake of these ions. Often, calcium is decreased secondary to increased binding to albumin. During prolonged respiratory alkalosis, bicarbonate ions are actively transported out of CSF, […]
Definition From Miller “Cardiac hormones are polypeptides secreted by cardiac tissues into the circulation in the normal heart. Natriuretic peptides, aldosterone, and adrenomedullin are hormones secreted by cardiomyocytes. Angiotensin II, the effector hormone in the renin-angiotensin system, is also produced by cardiomyocytes. The renin-angiotensin system is one of the most important regulators of cardiovascular physiology. […]
Definition The use of mannitol as a protective agent during renal transplantation stems from its ability to increase renal blood flow. This is thought to be due to the release of intrarenal vasodilating prostaglandins and atrial natriuretic peptide (ANP). A second perceived benefit of mannitol is related to its role as an oxygen free-radical scavenger […]
Definition Generally speaking, renal replacement therapy is necessary to prevent either fluid overload or endogenous poisoning. Indications for starting renal replacement therapy: Oliguria (urine output <200mL/12h) Anuria/extreme oliguria (urine output <50mL/12h) Hyperkalemia ([K]>6.5mEq/L) Severe acidemia (pH<7.1) Azotemia ([urea]>30mg/dL) Clinically significant organ (especially pulmonary) edema Uremic encephalopathy, pericarditis, or neuropathy/myopathy Severe hypo- or hypernatremia ([Na]<115 or […]
Definition Introduction to Potassium K+ outflow is responsible for phase III (repolarization) of the cardiac cycle. Insulin and beta agonists promote the influx of K+. Total body stores include 4200 mEq intracellularly, versus only 12 mEq in the plasma. Potassium excretion of K+ is determined primarily by [K+] and aldosterone levels Causes of Hyperkalemia in […]
Definition Perioperative oliguria is common, is almost always prerenal, and rarely implies acute renal failure. BUN to serum creatinine ratio of greater than 20:1 implies the existence of a prerenal syndrome. A doubling of the serum creatinine implies a halving of the GFR. Ketoacidosis, barbiturates, and cephalosporin antibiotics may artifactually increase the serum creatinine level […]
Definition Mechanism Decreased platelet factor 3 activity, abnormal platelet adhesiveness, and abnormal platelet aggregation all contribute to platelet abnormalities Treatment The simplest acute treatment for the bleeding patient with uremic platelet dysfunction is desmopressin (dDAVP), which is effective in at least 50% of such patients by increasing Factor VIII:von Willebrand Factor multimers from endothelial storage […]
Definition Renal failure is often complicated by elevations in potassium, phosphate, and magnesium and decreases in sodium and calcium. Additionally, chronic renal failure patients often present with an anion gap metabolic acidosis. Urea, creatinine, uric acid, sulfate, phosphate, phosphorus, lipids, cholesterol, neutral fats, and some amino/organic acids may accumulate, while albumin levels fall. Renal Failure: […]
Definition Patients with severe injuries who refuse blood transfusion present complex medical, legal, and moral problems. Objections to blood transfusions may arise for personal, medical, or religious reasons. For example, Jehovah’s Witnesses object to blood transfusion primarily on religious grounds. Methods available for minimizing blood loss: Preoperatively Discussion with the patient regarding which (if any) […]
Definition Typically, hemophilia A and B are treated with replacement of the missing factor (ie, factor VIII or factor IX concentrates). However, patients can develop factor inhibitors, which are IgG antibodies directed against the deficient factor. This usually occurs soon after replacement therapy has been started and is more common in patients with hemophilia A […]
Definition NMBD onset in the larynx and orbicularis oculi precedes the adductor pollicis by 1-2 mins. It appears that differences in regional blood flow may account for differences in NMBD onset and offset – thus, muscles such as the diaphragm, masseter, and laryngeal muscles (which receive relatively high amounts of blood flow) have both a […]
Definition Background Radicular pain is sharp, lancinating, radiating pain, often shooting from the low back down into the lower extremity in a radicular distribution. It is the result of a nerve root lesion or of inflammation. Clinically, it can be associated with pain, dermatomal hypesthesia, weakness of muscle groups innervated by the involved nerve roots, […]
Definition Exposure to radiation is best limited by proper barriers & maximizing the distance from the source of radiation. The amount of radiation varies according to the inverse square law: The amount of radiation varies inversely with the square of the distance. For example, the exposure at 4 feet will be 1/16th that at 1 […]
Definition Review of Documented Cases: Habib et. al. The FDA warning is based on 10 reported cases from 1997-2002 – these 10 cases were all with 1.25 mg or less, but in none of them could a definitive cause-effect relationship be described, and in five of them there were substantial confounding factors. Assuming that droperidol […]
Definition Pyloric stenosis is a medical emergency, not a surgical emergency. The patient should not be operated on until there has been adequate fluid and electrolyte resuscitation. According to Barash, the infant should have normal skin turgor, and the correction of the electrolyte imbalance should produce a sodium level that is >130 mEq/L, a potassium […]
Definition Pulseless ventricular tachycardia (VT) should be treated in the same manner as ventricular fibrillation (VF) and thus defibrillation should be performed immediately. Currently, most defibrillator units feature a biphasic waveform, using lower energies (120-150 Joules depending on the specific waveform employed) as compared to monophasic waveform defibrillation with a series of stacked progressively increasing […]
Definition Pulmonary artery hypertension is defined as having at least ONE of the following: PA systolic pressure > 35mmHg Mean PA pressure > 25mmHg at rest Mean PA pressure > 30mmHg during exercise According to the 2009 Fourth World Symposium on Pulmonary Hypertension, the exercise criteria should be abandoned and only a mean PA of […]
Definition VERY difficult to diagnose, the key is to remain suspicious and vigilant. Can lead to hemodynamic collapse. Intraoperatively, a sudden drop in ETCO2 is suggestive of increased deadspace which has many potential causes, including pulmonary embolism. Symptoms (in awake patients) include dyspnea, tachypnea, chest pain, palpitations. Signs include hemoptysis, rales, wheezing, split heart sounds. […]
Definition VERY difficult to diagnose, the key is to remain suspicious and vigilant. Can lead to hemodynamic collapse. Intraoperatively, a sudden drop in ETCO2 is suggestive of increased deadspace which has many potential causes, including pulmonary embolism. Symptoms (in awake patients) include dyspnea, tachypnea, chest pain, palpitations. Signs include hemoptysis, rales, wheezing, split heart sounds. […]
Definition Most cases of witnessed or otherwise recent aspiration of oropharyngeal or gastric contents associated with a new pulmonary infiltrate represent an acute chemical pneumonitis rather than an infection. These cases usually resolve without antimicrobial therapy, with deep breathing and coughing, or with chest physiotherapy, when required. There is no convincing evidence that early administration […]
Definition Pseudotumor cerebri (aka Idiopathic Intracranial Hypertension) commonly causes headache, papilledema, and visual symptoms (and enlarged blind spot) in the setting of isolated elevations in ICP. Several mechanisms have been considered as possible explanations for the pathophysiology of IIH. These include an increased rate of CSF formation, a sustained increase in intracranial venous pressure, or […]
Definition Plasma cholinesterase (also known as pseudocholinesterase, butyrylcholinesterase, or BuChE) is a serine hydrolase that catalyses the hydrolysis of esters of choline. It is most known for the metabolism of depolarizing neuromuscular blocking agent succinylcholine (also known as suxamethonium chloride, or SCh) by hydrolysis of the two ester links of choline to succinic acid. BuChE […]
Definition One of the hallmark metabolic responses to stress (i.e. injury, sepsis, surgery) is catabolism. Generally speaking, the degree of catabolism is proportional to the degree of stress. Catabolism is caused by increased breakdown of skeletal muscle. The subsequent release of amino acids provides some of the substrate for increased hepatic gluconeogenesis. During periods of […]
Definition A decrease in prostaglandin E2 (PGE2), along with exposure to oxygenated blood, causes the ductus arteriosus to close after birth. PGE1 (0.1 ug/kg/min) maintains ductus patency (and in some cases can reopen a closed duct), by directly acting on vascular smooth muscle. PGE1 is essential in patients with HLHS, AS, interupted arch, in which […]
Definition Patients with hypoplastic left heart syndrome (HLHS) have some combination of aortic and mitral atresia or stenosis, which due to decreases in flow, leads to underdevelopment of the left ventricle. The single right ventricle (RV) provides systemic blood flow from the pulmonary artery (PA) to the aorta via a patent ductus arteriosus. Prostaglandin E1 […]
Hyperkalemic periodic paralysis is an autosomal dominant disease leading to intermittent weakness associated with hyperkalemia and often precipitated by a potassium-rich meal, rest after exercise, or stressful situations. The paralysis lasts up to an hour. Caused (at least partly) by mutations in sodium channel NaV1.4 Cholinesterase inhibitors (ex. neostigmine), depolarizing muscle relaxants (SCh), and potassium can aggravate hyperkalemic periodic […]
Definition ECT requires both general anesthesia and paralysis. Pretreatment with glycopyrrolate may reduce the incidence of bradycardia and decrease oral secretions following the initial parasympathetic response. Induction is intravenous, followed by complete paralysis and placement of a bite block. According to Miller, “Methohexital (0.75 to 1.0 mg/kg) is the most commonly used drug for ECT anesthesia and […]
Definition Rare autoimmune disorder, causes peripheral muscle weakness. Antibodies are directed against calcium channels at the neuromuscular junction. Frequently a complication of malignancy (most commonly small cell lung ca). Cancer treatment relieves symptoms. Strength increases with increased use. May have autonomic abnormalities (gastroparesis, orthostatic hypotension or urinary retention). Subspecialty Neuroanesthesia Related Media Keyword history 86%/2015 […]
Definition Cross-matchinging is performed to determine if donor blood cells will be compatible with an intended recipient. It usually takes about 1 hour to perform. This is not the same as a type and screen which is a process used to determine a patients ABO-RH blood type AND screen for the common antibodies in the […]
Definition Barbiturates (except for the less-soluble phenobarbital) are mainly metabolized by the liver into inactive, water-soluble compounds by oxidation and then are renally excreted or conjugated to glucuronic acid and excreted in bile. The most significant aspect of the metabolism of barbiturates (e.g., phenobarbital, thiopental, methohexital) is their effect on the hepatic microsomal enzyme system […]
Definition ASRA last published guidelines regarding anticoagulation in 2010 (see reference below). What follows is summary of these guidelines. New guidelines will be published in 2014. Thrombolytics: There is insufficient data to support specific recommendations regarding a safe time period for neuraxial puncture to take place after receiving thrombolytics. If patient has indwelling catheter, ASRA […]
Definition In the continuum of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), the lungs are damaged following an insult that may be of pulmonary (e.g., pneumonia, aspiration pneumonitis) or extrapulmonary (e.g., sepsis, trauma, transfusion) origin. Regardless of the source of injury, ARDS is characterized by an acute onset, bilateral airspace infiltrates on […]
Definition Antiphospholipid syndrome describes an acquired autoimmune disorder characterized by venous and/or arterial thromboses as well as recurrent pregnancy loss. This syndrome may occur secondarily to autoimmune disorders such as systemic lupus erythematosus or rheumatoid arthritis, or it may occur in isolation. Characteristically, antiphospholipid syndrome results in mild prolongation of the aPTT and positive testing for […]
Definition Anemia has been observed in vivo to produce a hypercoaguable state. Platelet function, as measured by multiple electrode aggregometry and rotational thrombelastometry (TEG) has been shown to exhibit accelerated platelet aggregation when taken from increasingly anemic blood samples from 13 volunteers. Anemia also affects the coagulation cascade. In a sample of 29 patients with chemotherapy induced […]
Definition 5% albumin is prepared from human venous plasma and the sodium content is 145 ± 15 mEq/L with the usual concentration being 154 mEq/L. This is roughly the same sodium concentration as normal saline secondary to the albumin being mixed with normal saline. 25% albumin is provided in 50ml glass bottles and also contains […]
Definition Structural changes: Loss of neural tissue Thickened leptomeninges in spinal cord Decreased number of serotonin, acetylcholine, and dopamine receptors Functional changes: Reduction in cerebral blood flow (decreases about 10-20%, in proportion to neuronal loss) Decline in memory, reasoning, perception Disturbed sleep/wake cycle Increased threshold for many sensory modalities including touch, temperature, sensation, proprioception, hearing, […]
Definition Virtually all tissues have a requirement for glucose to function normally. Glycolysis is the major pathway of glucose metabolism and occurs in the cytosol of all cells. It can occur aerobically or anaerobically depending on whether oxygen is available. This is clinically significant because oxidation of glucose under aerobic conditions results in 32 mol […]
Definition Acute tubular necrosis (ATN) is a common diagnosis in acute renal failure, which is a rapidly progressing azotemia (increase in BUN/creatinine) that is often reversible. In order to effectively diagnose ATN, understanding the causes is helpful. There are many causes, but the following will be most encountered and associated with the practice of anesthesiology. ATN […]
Definition Once a coding patient is intubated, the provider should still do an assessment of ETT positioning (do not let ongoing CPR get in the way of your assessment). This includes visualizing chest expansion bilaterally, listening over the epigastrum and bilateral lung fields. Continuous waveform capnography in addition to clinical assessment is recommended as the most […]
Definition Type of Local Anesthetic: ester Pharmacokinetics: rapid onset time and short-lived duration of action. Rapid onset time is thought to be secondary NOT to its PKa (remember, PKa is approximately 9 and thus it is more protonated/less likely to cross cell membrane at physiologic pH) but because it can be used in relatively high concentrations due to […]
Definition Propofol has probably the commonly used intravenous anesthetic and is most frequently used for the induction of anesthesia. Like most intravenous anesthetics, Propofol works by increasing GABA-mediated inhibatory tone in the CNS. Propofol decreases the rate of dissociation of the GABA from the receptor, thereby increasing the duration of the GABA-activated opening of the […]
Definition Propofol infusion syndrome is a rare syndrome typically occurring after over 48 hours of propofol infusions at greater rates than 4 mg/kg/hr (67 ucg/kg/min). Features of the syndrome are acute refractory bradycardia leading to asystole in addition to at least one of the following: metabolic acidosis, rhabdomyolysis, hyperlipidemia, and/or enlarged liver. Also seen are […]
Definition Drugs 1. Antibiotics Aminoglycosides: Gentamicin & Tobramycin Tetracyclines Polymixins The following antibiotics do not prolong neuromuscular blockade: Erythromycin, penicillin, and cephalosporins. 2. Anticholinesterases 3. Calcium Channel Blockers 4. Local Anesthetics 5. Volatile Anesthetics Abnormal Physiologic States Hepatic Dysfunction Hypothermia Acidosis or Alkalosis Electrolyte Abnormalities Hypernatremia Hypocalcemia Hypokalemia Lithium Subspecialty General Related Media Keyword […]
Definition No trial has convincingly demonstrated the superiority of any given ventilatory mode over any other. ARDS Network data (NEJM 2000) provides high level evidence for limiting tidal volumes to no more than 6ml/kg in patients with ALI/ARDS. Whether this is accomplished with pressure or volume regulated ventilation is at the discretion of the treating […]
Definition Definition: Oliguria that is caused by hypoperfusion of the kidneys Causes: Most commonly due to hypovolemia (check a CVP); however, must also consider other causes such as cardiogenic shock, sepsis, acute blood loss. Diagonisis: Urinary sodium should be less than 20 as it is the kidney’s response to low perfusion It may also be […]
Definition Tests of renal tubular function used to differentiate pre-renal from tubular injury (acute tubular necrosis) test urinary concentrating ability. The normal tubular response to pre-renal conditions is to concentrate the urine for the perceived dehydration, thus maximizing water reabsorption. Urine osmolality is concentrated to over 450 mOs/kg compared to normal serum levels of 280-300 […]
Definition The preoptic anterior hypothalamus is the portion of the human brain that regulates temperature. The thermosensitive neurons located in the preoptic anterior hypothalamus receive information about peripheral and core temperature from skin thermoreceptors, mucus membrane, spinal receptors, the hypothalamus and endogenous substances like pyrogens, progesterone and glucose. These neurons then process and integrate the […]
Definition Bayes’ theorem (with regards to preoperative testing) states that the post-test probability of a person having a disease is related to both the sensitivity and specificity of said test AND the prevalence of the disease in the population – this can be summarized by the concept of positive predictive value (PPV), the percentage of […]
Definition Preoperative isolated systolic blood pressure hypertension and wide pulse pressure are strong independent predictors of postoperative renal dysfunction. The incidence and severity of ARF usually are greater when the preoperative serum creatinine level is greater than 2 mg/dL. Need for radiocontrast, volume depletion, aminoglycoside use, NSAIDs, septic shock, and pigmenturia are also risks. Note […]
Definition Virtually add sedating / analgesic medications can be used to sedate children prior to anesthesia, the important determinants are 1) available route 2) available agents 3) type/length of procedure 4) medical condition of the patient 5) psychological considerations (both family and patient) and 6) cost. The need for premedication does not begin until ~ […]
Definition There is an increased propensity for tachydysrhythmias (usually SUPRAventricular) during pregnancy – at least 50% of parturients will experience atrial and ventricular ectopy. Sinus tachycardia and SVT are common as well. Why? Hyperdynamic circulation, and increase awareness among some women. The causes of increased arrhythmias are multiple, including a change in Ca ion channel […]
Definition Normal hemoglobin is 12 g/dL. Clotting factors (I, VII, VIII, IX, X, XII) are elevated, protein S (anticoagulant) is decreased, and there is acquired resistance to protein C. Pregnancy is thus a hypercoagulable state. According to Gabbe, “There is increased nitrogen retention in pregnancy in both maternal and fetal compartments. There is an increase […]
Definition Decreased functional residual capacity is seen, typically falling from 1.7 to 1.35 litres, due to the compression of the diaphragm by the uterus. The compression also causes a decreased total lung capacity (TLC) by 5% and decreased expiratory reserve volume. Tidal volume increases with 30-40%, from 0.45 to 0.65 litres,[citation needed] and minute ventilation […]
Definition Pregnancy is known to be a state of “physiologic anemia” due to the disproportionate increase in plasma volume relative to red blood cell volume. This increase in blood volume is necessary to supply the fetus and placenta and begins very early in pregnancy. The plasma volume is already increased by 10-15% at 6 weeks […]
Definition Plasma volume increases 45% at term, RBC volume increases 20%, thus while pregnant patients have increased RBC mass, they appear anemic. Normal hemoglobin is 12 g/dL. During labor, contractions squeeze blood into the systemic circulation, and after delivery, uterine involution autotransfuses 500 cc/blood. Note that clotting factors (I, VII, VIII, IX, X, XII) are […]
Definition Pregnancy is known to be a state of “physiologic anemia” due to the disproportionate increase in plasma volume relative to red blood cell volume. This increase in blood volume is necessary to supply the fetus and placenta and begins very early in pregnancy. The plasma volume is already increased by 10-15% at 6 weeks […]
Definition Plasma volume increases 45% at term, RBC volume increases 20%, thus while pregnant patients have increased RBC mass, they appear anemic. Normal hemoglobin is 12 g/dl. During labor, contractions squeeze blood into the systemic circulation, and after delivery, uterine involution autotransfuses 500 cc/blood. Note that clotting factors (I, VII, VIII, IX, X, XII) are […]
Definition According to Miller, “Progesterone relaxes smooth muscle; consequently, it impairs esophageal and intestinal motility during pregnancy. Whether gastric emptying is delayed during pregnancy is controversial. Wong and coworkers suggest that the ingestion of 300 mL of water may actually enhance gastric emptying in healthy, term, nonobese, nonlaboring parturients. However, the risk of pulmonary aspiration […]
Definition Gastric emptying may be reduced by a cephalad pylorus and a progesterone-mediated decrease in gastric motility (this is controversial, see Miller p 2206). Stoelting recommends treating all pregnant women as though they had a full stomach (RSI?), using a cuffed endotracheal tube, and administering non-particulate antacids prior to induction. Note that Hawkins’ analysis of […]
Definition Postpartum hemorrhage (PPH) is an obstetrical emergency that can follow vaginal or cesarean delivery. It is a major cause of maternal morbidity, one of the top three causes of maternal mortality in both high and low per capita income countries. The incidence of PPH varies widely, depending upon the criteria to define the disorder. […]
Definition According to Niederman, “The entity of aspiration pneumonia in pregnant patients is a familiar one: in the 1960s as many as 2% of all maternal deaths were the result of aspiration. The pregnant woman is physiologically predisposed to aspiration. Factors including elevation of intragastric pressure due to the gravid uterus, a relaxed gastroesophageal sphincter […]
Definition Proteinuria of: >300 mg/24 h (mild preeclampsia) >5 g/24 h (severe preeclampsia) Urine dipstick >1+ Protein/creatinine ratio >0.3 Serum uric acid >5.6 mg/dL Serum creatinine >1.2 mg/dL Low platelets/coagulopathy Platelet count <100,000/mm3 Elevated PT or aPTT Decreased fibrinogen Increased d-dimer HELLP syndrome – a variant of severe preeclampsia and defined by the following: Hemolysis […]
Definition Definition: presence of uterine contractions of sufficient frequency and intensity that causes progressive effacement and dilation of the cervix prior to term gestation (between 20 and 37 wk). The earlier it occurs, the less the odds of survival of the fetus What exactly causes it? Nobody really knows, but there are certain things that […]
Definition Sepsis is an infection-induced syndrome defined as the presence of two or more manifestations of a systemic inflammatory response syndrome (SIRS). SIRS includes: Body temp greater than 38 C or less than 36 C. HR > 90/min. RR> 20/min or PaCO2 < 32mmHg. Leukocytosis (>12×109/L (>12,000/mm³)) or leukopenia (<4×109/L (<4000/mm³)). Mechanical control of ventilation […]
Definition Prerenal Hypovolemia Low renal blood flow (hypotension, low cardiac output, excess renal vascular resistance due to high SVR or renal clot, dissection, etc.) Intraabdominal hypertension (high CVP decreases the pressure gradient across the kidneys) Renal Acute tubular necrosis Contrast dye Tumor lysis Myoglobin Hemoglobin Postrenal Obstruction of the ureters or urethra Catheter dysfunction Subspecialty […]
Definition Postoperative jaundice is defined as the elevation of bilirubin that occurs after the completion of surgery and has many possible causes, associated laboratory findings, and implications. It can, but not always, be associated with icterus. Causes of postoperative jaundice can be divided into several functional categories including: prehepatic, intrahepatic, and posthepatic. Prehepatic causes are […]
Definition Acute tubular necrosis (ATN) is the most common form of renal failure following surgery and is generally classified as either hypotensive (low cardiac output, low map, cross-clamp, cpb) OR nephrotoxic (inflammation [CPB], infection, atheroembolism, rhabdomyolysis, drugs [NSAIDs, aminoglycosides, cyclosporine, tacrolimus], toxins, or contrast-dye). Note that, according to Miller, “Mechanical ventilation and positive end-expiratory pressure […]
Definition The development of postoperative apnea is a major concern with surgery in neonates. Infants at highest risk are those born prematurely, those with multiple congenital anomalies, those with a history of apnea and bradycardia, and those with chronic lung disease. It is thought that the etiology is multifactorial. Decreased ventilatory control and hypo-responsiveness to […]
Definition Most common cause of postpartum hemorrhage. Treated with synthetic oxytocins (ex. oxytocin injection, Pitocin®), which do NOT contain vasopressin – if given rapidly (ex. 10 U Pitocin® rapidly, despite that the manufacture recommends only 5 U slowly), these agents can cause vasodilation/hypotension and tachycardia [Pinder AJ et al. Int J Obstetr Anesth 11: 156, […]
Definition Mild postoperative hepatic dysfunction is not uncommon in healthy individuals. Several proposed mechanisms include decreased blood flow, sympathetic stimulation and the surgical procedure itself, especially if in close proximity to the liver. Moderate increases in LDH and transaminases have been seen in these procedures regardless of anesthetic technique used. When elevations of liver function […]
Definition During the postoperative period, Diabetes insipidus (DI) is most commonly associated with: Pituitary surgery Traumatic brain injury Subarachnoid hemorrhage (especially associated with an anterior communicating artery aneurysm) Most patients with DI do NOT require specific treatment if they have ready access to fluids. Indeed, most DI after pituitary surgery is transient and no permanent. […]
Definition Postobstructive pulmonary edema (POPE) is a noncardiogenic cause of pulmonary edema with an incidence of 0.05-0.1%. Risk factors include male gender, head and neck surgeries, OSA, acromegaly, difficult intubation, and young age (probably associated to the ability to generate a significant pressure change). POPE is categorized as type I (inhalation against an obstruction) or […]
Definition Treatment options for post-herpetic neuralgia include TCAs (amitriptyline, nortriptyline, desipramine and imipramine), serotonin noradrenaline reuptake inhibitors (venlafaxine and duloxetine), selective serotonin reuptake inhibitors (data are conflicting), gabapentin and pregabalin (may improve both pain and quality of life), oxycodone and tramadol, as well as 5% lidocaine patches and topical capsaicin (neither of which should be […]
Definition Herpes zoster is caused by the varicella zoster virus which lies dormant in dorsal root ganglia and becomes active again during immunosuppression or as immunity declines with advancing age. Herpes zoster most commonly involves the thoracic and trigeminal dermatomes with the most common being the thoracic distribution , followed by the ophthalmic division of […]
Definition Tonsillectomy is one of the most common childhood operations. Possible postoperative complications of tonsillectomy include pain, postoperative nausea and vomiting (PONV), delay to oral intake, airway obstruction with respiratory compromise, and primary or secondary postoperative bleeding. IV Dexamethasone has been shown to decrease PONV and increase time to oral intake when given perioperatively. NSAIDs […]
Definition The risk of a headache after accidental dural puncture (i.e., with an epidural needle) is approximately 50%. However, keep in mind that headaches occur in 12% of all parturients who have an epidural (and 15% of parturients who don’t have an epidural). For patients whose dura is violated intentionally (ex. spinal anesthetic, CSE, DPE), […]
Definition Physiologic changes resulting from CPB that are potentially damaging to the kidneys include reduced renal perfusion, loss of the renal blood flow autoregulatory reflexes, and inflammatory responses. Consequently, one of the greatest predictors of post-CPB renal dysfunction is CPB duration. Acute renal failure occurs in approximately 7-8% of adult cardiac patients and is more […]
Definition Preoperative evaluation of heart transplant patients should focus on cardiac functional status and any symptoms or signs of heart failure. All such patients should be evaluated with ECG and TTE prior to surgery. Invasive monitors should be placed if/when warranted by clinical status and surgical procedure.The transplanted heart cannot respond to indirect acting agents […]
Definition Studies in children are often limited to data on vomiting only and not nausea. The incidence of vomiting is twice as high among children as among adults, but it is rare in children younger than 2 years of age. The average incidence of PONV in children greater than 3 yo is 40%. The risk […]
Definition Polymorphic Ventricular Tachycardia (Torsade de Pointes) is a ventricular arrhythmia characterized electrographically by a wide complex tachycardia that appears to twist around a single point, as the amplitude of the waves enlarge and shrink. Torsades usually occurs in a “pause dependent” fashion. There is a run of tachycardia, or an ectopic beat, and then […]
Definition Poiseuille’s Law The flow of fluids through an IV catheter can be described by Poiseuille’s Law. It states that the flow (Q) of fluid is related to a number of factors: the viscosity (n) of the fluid, the pressure gradient across the tubing (P), and the length (L) and diameter(r) of the tubing. Important […]
Definition Tirofiban is a non-peptide reversible antagonist of fibrinogen binding to the GP IIb/IIIa receptor, the major platelet surface receptor involved in platelet aggregation. Subspecialty General Related Media Keyword history 31%/2011 See Also: Sources PubMed
Definition Local anesthetics are weakly basic drugs that are principally bound to 1-acid glycoprotein. Placental transfer depends on three factors: (1) pKa, (2) maternal and fetal pH, and (3) degree of protein binding. Except for chloroprocaine, fetal acidosis produces higher fetal-to-maternal drug ratios because binding of hydrogen ions to the nonionized form causes trapping of […]
Definition According to animal (sheep) studies, peak maternal/fetal levels of atropine are 8x higher than glycopyrrolate after intravenous maternal administration. Note that drugs with a MW > 1000 Dalton do not readily cross the placenta, whereas drugs with a MW < 500 Dalton easily cross the placenta unless their they are highly ionized. Atropine (MW […]
Definition Placental exchange can occur by one of five mechanisms: Bulk Flow (water) Active Transport (Amino acids, vitamins, ions, Ca, Fe) Pinocytosis (large molecules, such as immunoglobulins) Breaks (direct mixing of blood—responsible for Rh sensitization) Diffusion (Respiratory gases and most drugs used in anesthesia) All inhalational agents and most intravenous agents freely cross the placenta; […]
Definition Placenta accreta occurs when all or part of the placenta attaches abnormally to the to the myometrium, rather than being restricted within the decidua basalis. Placenta accreta is different from Placenta increta (invading into the myometrium) and placenta percreta (extending through the myometrium and attaching to surrounding structures). Risk factors: An important risk factor […]
Definition Even a nonfunctioning pituitary adenoma can cause symptoms. Pressure on the optic nerve can cause blurriness or vision loss at the peripheries, classically bitemporal hemianopsia. This is considered a progressive symptom, meaning it will continue to get worse so the patient needs surgery in order to prevent further loss and hopefully improve vision. The […]
Definition The three keys to a successful intervention are a thorough investigation, an experienced intervention team, and rehearsed intervention plan. These factors are well discussed in the review by Silverstein et al. and summarized as follows. The investigation, which may take weeks, is ideally performed confidentially by an experienced team drawn from the human resources, […]
Definition A recent survey of phrenic nerve stimulators from Australia noted a high incidence of revision operations (42%). Complications in this cohort (not necessarily due to the stimulators themselves) included “recurrent respiratory tract infections, urinary tract infections, pressure sores, kyphoscoliosis, neurogenic bladder and muscle spasms“. Phrenic nerve damage may occur at the time of surgery, […]
Definition Preoperative Hypertension Treatment: Adrenergic blockade is THE most helpful in treating hypertension preoperatively.These drugs probably reduce the complications of hypertensive crisis, the wide BP fluctuations during manipulation of the tumor (especially until venous drainage is obliterated), and the myocardial dysfunction that occurs perioperatively. A reduction in mortality associated with resection of pheochromocytoma (from 40% […]
Definition Preoperative Hypertension Treatment: Adrenergic blockade is THE most helpful in treating hypertension preoperatively. These drugs probably reduce the complications of hypertensive crisis, the wide BP fluctuations during manipulation of the tumor (especially until venous drainage is obliterated), and the myocardial dysfunction that occurs perioperatively. A reduction in mortality associated with resection of pheochromocytoma (from […]
Definition Introduction to Pheochromocytoma 25-50% of Pheo patients who die in hospital do so during anesthesia induction or surgery. Can be part of multiple endocrine adenoma IIa or IIb, autosomal dominant. MEN IIa is medullary thyroid, parathyroid adenoma, and pheo. MEN IIb aka pheo in assoc w/ phakomatoses (von Recklinghausen neurofibromatosis, VHL, cerebellar hemangioblastoma). MRI […]
Definition “A few drugs may diminish the effects of a nondepolarizing NMBD, including calcium, corticosteroids, and anticonvulsant (phenytoin) drugs.” – Stoelting (Basics of Anesthesia) p143 Interesting, if phenytoin is acutely administered to a phenytoin-naive patient, phenytoin will potentiate the effect of neuromuscular blockade; however, if the patient is on chronic phenytoin, neuromuscular blockers will have […]
Definition Labor is defined as progressive cervical dilatation in association with uterine contractions. Labor can be divided into the following stages: Stage I: A) Latent phase Variable duration Starts at onset of labor Complete when the rate of cervical dilation increases (~ 3 cm) B) Active phase (contractions every 2-3 mins, last 1 min, up […]
Definition There is considerable variability and unpredictability in the duration of action of non-depolarizing muscle relaxants in the neonate. Continual organ maturation during the neonatal period leads to changes in metabolism and clearance of the non-depolarizing agents. Vecuronium is considered an intermediate-acting muscle relaxant in children and adults; however, in infants younger than 1 year […]
Definition Treatment options are limited and there is no consensus among experts regarding which treatment is optimal. Pharmacologic options include opioids, anticonvulsants, antidepressants (amitriptyline, [TCA] and nortriptyline and desipramine [secondary amines]), pregabalin, and memantine (oral NMDA receptor antagonist). Non-pharmacologic treatment includes transcutaneous electrical nerve stimulation (TENS), deep brain stimulation, spinal cord stimulation, sympathetic blockade, acupuncture, […]
Definition The human body has four native buffer systems – bicarbonate, hemoglobin, protein, and phosphate systems. An ideal buffering system has a pKa of ~ 7.4 (normal physiologic pH). Bicarbonate has a pKa of 10.3, which is NOT ideal in normal physiologic conditions. In fact, the pH range of effectiveness is probably ~ 5.1 – […]
Definition Solutions: Many solutions are commonly used. Electrolytes can be added to meet the patient’s needs. Patients who have renal insufficiency and are not receiving dialysis or who have liver failure require solutions with reduced protein content and a high percentage of essential amino acids. For patients with heart or kidney failure, volume (liquid) intake […]
Definition Components of Oxygen in Blood Oxygen delivery to the periphery depends on the oxygen content of blood and tissue blood flow. The oxygen content of blood has two components: oxygen bound to hemoglobin and oxygen dissolved in plasma. Oxygen bound to hemoglobin is generally the much greater contributor to oxygen content. (One notable exception […]
Definition The peripheral nervous system is divided into somatic and autonomic components. The somatic nervous system includes the sensory and motor nerves that innervate the limbs and body wall. Sensory nerve fibers in the peripheral nerves are the peripheral axonal process of neurons in the dorsal root ganglion. The motor axons are the processes of […]
Definition Cardiac output at term is increased 40%-50% over pre-pregnant values. During labor, further increases in cardiac output take place, with a 10-25% increase over pre-labor values in the first stage and up to 40% in the second stage of labor. Cardiac output is increased by as much as 80% immediately after delivery. By 24 […]
Definition During the perioperative period, major physiologic changes occur that may alter the myocardial oxygen supply/demand balance. Surgery induces a catecholamine surge that increases myocardial oxygen demand and stimulates the release of inflammatory cytokines that increase thrombotic risk. Fluid shifts may contribute to hypotension, or alternatively increased myocardial wall stress. Pain, in conjunction with all […]
Definition Overview Anaphylaxis is a severe, life threatening hypersensitivity reaction with rapid onset that is primarily mediated by IgE. It occurs in 1 in 10,000 to 20,000 anesthetic procedures, though the exact incidence is likely underestimated due to underreporting. The most common causative agents are neuromuscular blocking agents (NMBAs), followed by latex and antibiotics. Other […]
Definition PEEP has a protective effect in acute lung injury, and probably in the prevention of ventilator induced lung injury. The reasons proposed for this effect are: Curtailment of quantitative and qualitative surfactant depletion Reduced shearing stresses within junctional tissues, reduced parenchymal injury and cytokine release. PEEP only prevents derecruitment (it does not recruit lung […]
Definition Adverse cardiovascular effects of PEEP can include progressive reductions in cardiac output as mean airway pressure and, secondarily, mean intrathoracic pressure rise. The principal mechanism appears to be a progressive decrease in venous return to the heart. Other mechanisms may include leftward displacement of the interventricular septum (interfering with left ventricular filling) because of […]
Definition The major effect of PEEP on the lungs is to increase FRC. In patients with decreased lung volume, both PEEP and CPAP increase FRC and tidal ventilation above closing capacity, improve lung compliance, and correct ventilation/perfusion abnormalities. The resulting decrease in intrapulmonary shunting improves arterial oxygenation. Their principal mechanism of action appears to be […]
Definition Positive end-expiratory pressure will increase intrathoracic pressure, leading to: decreased venous return increased RV afterload decreased ventricular compliance decreased ventricular contractility PEEP will decrease cardiac output in hypovolemic and normovolemic patients because of the drop in venous return. If a patient has poor LVEF or CHF, PEEP will reduce LV transmural pressure, reducing afterload, […]
Definition Pediatric obstructive sleep apnea (OSAS) is an example of sleep disordered breathing which refers to a clinical spectrum of repetitive episodes of complete or partial obstruction of the airway during sleep. The prevalence is likely ~2% of the pediatric population. In contrast to adults where redundant soft tissue from obesity is the cause, in […]
Definition Mapelson systems are classified based on the location of the fresh gas flow inflow and overflow valves relative to the patient connection. They all share the benefit of decreased resistance due to the absence of unidirectional valves and canisters. Unfortunately rebreathing and the resulting hypercarbia and respiratory acidosis become a problem (although rebreathing conserves […]
Definition Static compliance is measured in the absence of gas flow, and is based on plateau pressure: Cstat = Vt/(Pplat – PEEP) Dynamic compliance is measure in the presence of gas flow, and is based on peak pressure: Cdyn = Vt/(Ppeak – PEEP) Remember these three scenarios to understand how compliance curves will change: Pulmonary […]
Definition A post-dural puncture headache (PDPH) occurs after intentional (in the case of spinal anesthesia) or accidental (in the case of epidural anesthesia) puncture of the dura mater. The resulting loss in CSF pressure leads to traction on the meninges and a severe headache, which is often positional and accompanied by nausea. Treatment Most patients […]
Definition A Patent ductus arteriosus (PDA) is a vascular communication typically located between the proximal descending aorta and the main pumonary artery. This results in a left to right shunt with increased pulmonary blood flow and pulmonary hypertension if left untreated. Indomethacin can be administered to infants with PDAs to promote closure, but surgical intervention […]
Definition Small PDAs are asymptomatic. Hemodynamically significant PDAs create a left to right shunt and may lead to congestive heart failure. Aortic runoff reduces diastolic pressure and decreases coronary, cerebral, and abdominal perfusion. Echocardiography assists in the diagnosis. Subspecialty Pediatric Anesthesia Related Media Keyword history 36%/2010 See Also: Sources Smith’s Anesthesia for Infants and Children, […]
Definition A number of surveys indicated that most parents prefer to be present during the induction of anesthesia regardless of the child’s age.1,2 A majority of parents believe that they are of some help to their child and to the anesthesiologist during the induction process.(2) Parental presence is associated with increased parental satisfaction not only […]
Definition Parental presence during the induction of anesthesia has been suggested as an alternative to sedative premedication. Potential benefits include reduced need for preoperative sedation, reduced anxiety, and increased compliance during induction of anesthesia. Common objections for parental presence include delays in operating room schedule, crowded operating rooms, adverse parental reactions during induction, and distraction […]
Definition Patients with a spinal cord injury at T7 or higher are at risk for autonomic hyperreflexia. Normally, the reflexic response to cutaneous, visceral (bladder), and proprioceptive stimuli are to some extent attenuated by descending, inhibitory impulses. However, in patients with SCI, these impulses may be curtailed, leading to uninhibited spinal cord reflexes and consequent […]
Definition As the temperature of blood decreases, the solubility of O2 and CO2 increases, which consequently lowers their partial pressures (decreases PaO2 and PaCO2). This especially becomes important during cold cardiopulmonary bypass. PaCO2 decreases by approximately 2 mm Hg and PaO2 decreases by approximately 5 mm Hg per °C below 37°C. Therefore if an ABG […]
Definition Discharge from PACU Aldrete’s original scoring system has been modified, but originally required a score of 9 or greater to leave the PACU (i.e. you could only miss one point on the following scale) Adapted from Table 85-14: Criteria for Determination of Discharge Score for Release from the Postanesthesia Care UnitActivity: Able to move […]
Definition The PACU is traditionally divided into phases 1 and 2. Phase 1 has monitoring and staffing ratios equivalent to the ICU. Phase 2 is a transitional period between intensive observation and either the surgical ward or home. The concept of bypassing or “fast-tracking” phase 1 is becoming more common as fast-offset anesthesia agents and […]
Definition Pacemakers activate depolarizations with electrical impulses and these appear as pacing spikes on the ECG. In ventricular pacing, a pacing spike will be followed by a broad QRS complex (because the depolarization is not conducted via the normal fast conduction pathways.) When the atria are being paced via an atrial lead the pacing spike […]
Definition Paced chamber [O, A, V, D (A+V)] Sensed chamber [O, A, V, D (A+V)] Response to sensed event [O, Inhibited, Triggered, D (I+T)] Rate modulation [O, R] Multisite pacing [O, A, V, D (A+V)] Note that T (Triggered) is only an option for the for 3rd letter of the pacemaker designation and is only […]
Definition Mechanism of Action After parenteral injection, sodium nitroprusside enters red blood cells, where it receives an electron from the iron (Fe2+) of oxyhemoglobin. This nonenzymatic electron transfer results in an unstable nitroprusside radical and methemoglobin (Hgb Fe3+). The former moiety spontaneously decomposes into five cyanide ions and the active nitroso (NO) group. The cyanide ions can […]
Definition Electromagnetic interference (EMI) can cause malfunction of pacemakers and internal cardiac defibrilators (ICDs). The most common cause of EMI is monopolar electrocautery, especially if it is within 6 inches of the pulse generator. It can inhibit pacing, damage pulse generator, and cause inappropriate tachycardia therapy. In the event of surgery above the umbilicus, reprogramming […]
Definition The oxyhemoglobin dissociation curve shows the relationship between the hemoglobin saturation (SO2) at different oxygen tensions (PO2). The P50 is the oxygen tension at which hemoglobin is 50% saturated. The normal P50 is 26.7 mm Hg. Shifting the curve to the left or right has little effect on the SO2 in the normal range […]
Definition Oxytocin is structurally similar to anti-diuretic hormone (ADH, vasopressin) and both are released from the posterior pituitary. Onset is ~1 min when given IV, and t1/2 is ~5 min. The most common side effect is hypotension Prolonged infusions can result in water retention and hyponatremia due to cross reactivity with the vasopressin receptor, giving […]
Definition Mechanism of hypoxia during one lung ventilation In the lateral decubitus position the dependent lung is under ventilated as it is compressed by the compression of the abdominal contents and the weight of the mediastinum. The nondependent lung is relatively over ventilated secondary to increased compliance as the corresponding hemithorax is opened. There is […]
Definition The brain dead donor may produce inadequate amounts of antidiuretic hormone (ADH) from the posterior pituitary resulting in diabetes insipidus (DI) and urine volumes of over 1000 mL/hour, This frequently causes hypernatremia, which can affect the funciton of the transplant in the organ recipient. Diabetes insipidus contributes to hyperosmolarity, hemodynamic instability, and electrolyte abnormalities. […]
Definition The brain dead donor may produce inadequate amounts of antidiuretic hormone (ADH) from the posterior pituitary resulting in urine volumes of over 1000 mL/hour, resulting in diabetes insipidus. This frequently causes hypernatremia, which can affect the funciton of the transplant in the organ recipient. Diabetes insipidus contributes to hyperosmolarity, hemodynamic instability, and electrolyte abnormalities. […]
Definition Bradycardia in donors may be sinus (ex. as part of Cushing’s triad), or non-sinus (ex. if the sinus node fails). Anticholinergics may not be effective if vagal nuclei have been compromised, thus direct-acting agents (ex. isoproterenol, a.k.a. Isuprel, 1.0 μg IV) are preferable. If isoproterenol is not available, consider dobutamine, epinephrine, or dopamine. External, […]
Definition Anesthesia accounts for 5.6% of perioperative costs. The operating room as a whole accounts for 40% of total hospital expenses, and it generates 70% of the revenue.1 As one might expect, there is considerable interest in reducing these costs in order to maximize profitability. Operating room cost can be described in terms of fixed […]
Definition The general “Rule of Thumb” for drug administration in elderly folks is “to start low and go slow.” This is no different for opioids. In general, elderly patients have lower analgesic requirements secondary to increased brain sensitivity to opioids with age. According to Miller, sufentanil, alfentanil, remifentanil, and fentanyl are twice as potent in […]
Definition Opioid Antagonists Naloxone (Narcan) Pure antagonist of μ, κ, and δ receptors. Must be administered with caution – if too aggressive, can elicit extreme pain, HTN, arrhythmias, pulmonary edema, and death (thought to be due to massive catecholamine response to pain), as well as opioid withdrawal symptoms in patients who require opioids. Peak effect […]
Definition Opioid neurotoxicity refers to neuropsychiatric symptoms associated with high dose opioids, including cognitive dysfunction, sedation, hallucinations, myoclonus, seizures, and hyperalgesia. One or all of these symptoms may be present. Neurotoxicity may occur with any opioid but is more likely to occur with those with active metabolites, such as meperidine and morphine. It may also […]
Definition One lung ventilation-Hypoxia treatment FiO2 100 % Recheck positioning of double-lumen tube for correct placement using fiberoptic bronchoscope. Suction both lumens of double-lumen tube for secretions or mucous plugs May need to notify surgeons to stop and return to two-lung ventilation. Or at least ask for periodic reinflation/recruitment maneuvers of the nondependent collapsed lung. […]
Definition For preoperative risk assessment, the age of a myocardial infarction (MI) is important. Acute MI is defined as occurring within the past 7 days. Recent MI is defined as happening between 7 and 30 days ago. Both acute and recent MIs, along with unstable angina, are considered unstable coronary syndromes and place the patient […]
Definition Odds: the ratio of the probability that an event will occur versus the probability that the event will not occur, or probability / (1-probability). For example, if you are normally on call 2 out of 7 days in a week, then the odds of you being on call on a certain day of the […]
Definition History In 1908, Aschner described a decrease in heart rate as a consequence of applying pressure directly to the eyeball. This phenomenon would eventually be termed “the oculocardiac reflex” and is defined clinically as a decrease in heart rate by 10% following pressure to the globe or traction of the ocular muscles. The reported […]
Definition Obstructive Sleep Apnea (OSA) is defined as complete apnea for 10 seconds, five times per hour, associated with a 4% decrease in SaO2 (while sleeping). Hypopnea is a less-severe form of obstruction (50% reduction in airflow, also accompanied by a 4% fall in SaO2). Both OSA and hypopnea require a sleep study for diagnosis. […]
Definition While obesity has been associated with difficult pre-hospital intubation (1-3), in the operating room setting, it appears that OSA, and not obesity per se, may be the important risk factor. As with all patients, the airway of obese patients deserves a thorough physical exam (Mallampati score/mouth opening, cervical spine mobility, temporomandibular joint mobility, teeth […]
Definition Total O2 content is expressed by the following equation: O2 content (CaO2) = ([SaO2 x Hgb x 1.31 ml/dl blood]) + ([0.003 ml/dl blood per mmHg x PO2) where Hgb is hemoglobin concentration and SaO2 is hemoglobin saturation at the given PO2. Oxygen transport is dependent on both respiratory and circulatory function. Total O2 […]
Definition The purpose of the E-cylinder is to provide backup oxygen in case the pipeline supply fails. They are attached to the anesthesia machine using a hanger yoke assembly and a pin index safety system (PISS). They MUST BE CHECKED prior to administering anesthesia, but always remember to close them after the check (unless you […]
Definition Oxygen delivery is defined as the amount of oxygen delivered to the capillaries per minute. It is calculated by the following formula: DO2=CO x CaO2 (mL/min/m2) So oxygen delivery is dependent on cardiac output as well as the arterial oxygen content. The arterial oxygen content is based on the amount of hemoglobin (Hb), the […]
Definition Oxygen delivery is defined as the amount of oxygen delivered to the capillaries per minute. It is calculated by the following formula: DO2=CO x CaO2 (mL/min/m2) So oxygen delivery is dependent on cardiac output as well as the arterial oxygen content. The arterial oxygen content is based on the amount of hemoglobin (Hb), the […]
Definition O2 delivery to the fetus (DO2) is dependent on blood flow to the uterus, the amount of hemoglobin present in maternal blood, and percent of oxyhemoglobin (as with other organs). All three of these factors are modifiable, particularly uterine blood flow – maximize cardiac output (volume, beta agonists/increase contractility, reduction in afterload), and avoid […]
Definition Norepinephrine (NE) is an endogenous catecholamine and a direct acting adrenergic agonist. It is synthesized from dopamine by dopamine-beta-hydroxylase. NE is the body’s primary adrenergic neurotransmitter. It’s effects are mediated primarily through interaction at α-1 and β-1 receptors. It also has α-2 activity, though this primarily serves as a negative feedback system. NE is […]
Definition According to Miller, “In conditions associated with insulin resistance, there seems to be a proliferation of AChRs beyond the junctional area… the extrajunctional immature receptors can reappear soon after upper and lower motor denervation and in certain pathologic states (e.g., burns, immobilization, chronic muscle relaxant therapy, loss of electrical activity).” Upregulation of Extrajunctional AChR […]
Keyword history 5%/asked 2013 See also ABA:Cardiac vascular anatomy – TEE ABA:TEE – Ventricular wall anatomy OpenAnesthesia.org:Course in Basic TEE
Definition Halogenated volatile anesthetics have a potentiating effect on nondepolarizing muscle relaxants. The mechanism appears to be incompletely understood, but is likely a combination of: effect on central motor neurons augmentation of the NMB’s affinity for the receptor site inhibition of post-synaptic nicotinic acetylcholine receptors Clinically, the presence of inhaled anesthetics will decrease the ED50, […]
Definition According to Miller, potency of a NMBD is best described as the effective dose – “The dose of a neuromuscular blocking drug required to produce an effect (e.g., 50%, 90%, or 95% depression of twitch height, commonly expressed as ED50, ED90, and ED95, respectively“. Thus, the ED95 is the amount of NMBD required to […]
Definition General Comments Peripheral nerve stimulators are theoretically the most reliable monitoring method, although visual estimates of TOF are unreliable. Most commonly, electrodes are placed over the ulnar nerve (elbow or wrist, recovers relatively late) or facial nerve (lateral face, recovers relatively early) – the orbicularis oculi (CN VII) more closely reflects blockade of the […]
Definition Lambert-Eaton syndrome is a paraneoplastic syndrome characterized by proximal muscle weakness that typically begins in the lower extremities but may spread to involve upper limb, bulbar, and respiratory muscles. It is usually associated with small cell carcinoma of the lung but may also be seen with other occult malignancies or as an idiopathic autoimmune […]
Definition The neuromuscular junction (NMJ) is the synapse (junction) between the axon terminal of a motor neuron and the motor end-plate. The motor end-plate is the excitable portion of the muscle cell membrane responsible for initiating the action potential (the cascade of ion shift which produces the electrical current across the cell and ultimately muscle […]
Definition N2O increases CBF, CMR, and ICP. Mostly due to cerebral vasodilation, although partly due to sympathoadrenal stimulation. This effect is lessened by co-administration of IV anesthetics, but may be worsened by addition of volatile. CBF response to CO2 is preserved w/ N2O administration. According to Miller, “There is no uniform agreement about the effect of N2O on CMR… […]
Definition Nitrous oxide will move into air-filled cavities in the body that normally contain nitrogen; so as nitrous oxide transfers from the blood into the space, nitrogen transfers out. However, nitrous oxide is 34 times more soluble than nitrogen in blood. Thus, substantial quantities of nitrous oxide leave the blood and enter the bowel, but […]
Definition Mechanism of Action of Sodium Nitroprusside: After parenteral injection, sodium nitroprusside enters red blood cells, where it receives an electron from the iron (Fe2+) of oxyhemoglobin. This nonenzymatic electron transfer results in an unstable nitroprusside radical and methemoglobin (Hgb Fe3+). The former moiety spontaneously decomposes into five cyanide ions and the active nitroso (NO) […]
Definition Uterine relaxants may be required to assist in the removal of retained placental products or correction of a uterine inversion. Several pharmacologic agents can be used, and should likely be selected based on the cardiopulmonary status of the patient (hypotensive vs. normotensive, spontaneously breathing versus intubated, etc.) Uterine Relaxants β-agonists Magnesium Nitroglycerin Volatile anesthetics Subspecialty Related Media […]
Definition Nitric Oxide is a colorless, odorless gas that is relatively insoluble in water and is found in naturally atmosphere at concentration range of 10-500 ppb. The concentration has been reported as high as 1500ppb or (1.5ppm) in areas of high traffic or lightning. NO is potent dilator of the pulmonary circulation and has been […]
Definition Hypotension is a late finding in pediatric patients (children may maintain a normal blood pressure until 35% of blood volume is lost).Tachycardia is sensitive but not specific indicator. Prolonged capillary refill (> 2 seconds), especially when combined with tachycardia, is more specific, although it may be difficult to measure. Cold skin and decreased urine output may be present.Weak pulses, mottling, cyanosis, and impaired consciousness may […]
Definition In addition to abuse of IV agents, including propofol, [Wischmeyer et al], abuse of volatile agents has also been documents [Zacny and Galinkin]. It is estimated that the incidence of substance abuse among physicians is 2.1% annually (or 7.9% over one’s lifetime) [Hughes]. Drug abuse in anesthesiologists is estimated to be between 1 […]
Definition Neutral thermal environments (34-35°C or 93.2-95°F) are generally recommended in the context of neonatal resuscitation. (Source 1) There are four basic mechanisms through which heat is transferred from the newborn to the environment: radiation, conduction, convection and evaporation. (Ref. 1) Nonshivering thermogenesis is the main mechanism of heat production in neonates. A newborn infant […]
Definition Succinylcholine (SCh) is a depolarizing neuromuscular-blocking agent, which produce sustained opening of the nicotinic cholinergic receptor channel. Under normal conditions, post-junctional membrane depolarization results in leakage of potassium that produces an increase of 0.5 – 1.0 mEq/L in serum K+ concentration. When SCh depolarizes muscle that has been traumatized (crush injury) or denervated (upper […]
Definition Rocuronium: elimination half-time increased by 37%. Both volume of distribution and plasma clearance are increased. That said,according to Miller, “the duration of action of single and repeated doses, though, is not significantly affected. Vecuronium: elimination half-time increased by 24-56%. Vecuronium is primarily eliminated via hepatic mechanisms, however, its elimination half-life is still increased in […]
Definition Vecuronium is an intermediate acting nondepolarizing neuromuscular blocking agent of the steroidal compound variety. The initial intubating dose is 0.1-0.2 mg/kg followed by supplemantal doses of 0.02 mg/kg after intubation. Vecuronium undergoes approximately30-40% metabolism by the liver and is eliminated by the liver (50-60%) and kidney (40-50%). Roughly 12% gets converted to an active metabolite 3-desacetylvecuronium that has approximately 80% of the potency of […]
Definition The four common side effects/complications include respiratory depression, urinary retention, nausea/vomiting, and pruritus, the most serious being a dose-dependent, delayed respiratory depression. Early respiratory depression occurs within 2 hours and is likely due to systemic absorption. Delayed respiratory depression can occur between 6-24 hours after administration. It results from cephalad migration to the ventral […]
Definition According to Miller, “the analgesic effects of opioids arise from their ability to directly inhibit ascending transmission of nociceptive information from the spinal cord dorsal horn and to activate pain control circuits that descend from the midbrain, via the rostral ventromedial medulla (RVM), to the spinal cord dorsal horn…In the spinal cord, opioids act […]
Lower Extremity Femoral Below inguinal ligament 1 cm lateral to femoral artery At level of femoral crease Sciatic Classic posterior approach Line drawn between greater trochanter and PSIS Needle insertion 4 cm distal to midpoint of these landmarks Parasacral approach Line drawn between ischial tuberosity and PSIS Needle insertion 6 cm caudal to PSIS on […]
Definition Sodium and Potassium in the resting cell: The resting cell has an electrical potential-resting membrane potential- approximately -60 to -70mV in neurons (0 is convention for extracellular potential). Neurons at rest are more permeable to K+ ions than Na+ ions because of K+ leak channels; thus, membrane potential is closer to equilibrium potential of K+ […]
Definition For Neostigmine a maximum dosage is in the range of 60 to 80 mcg/kg. Although large doses of the drug will result in more rapid antagonism, there seems to be a “ceiling effect”. The maximum effective dose, beyond which further amounts of anticholinesterase will not produce any greater antagonism. Also, be mindful excessive neostigmine […]
Definition The development of postoperative apnea is a major concern with surgery in neonates. Infants at highest risk are those born prematurely, those with multiple congenital anomalies, those with a history of apnea and bradycardia, and those with chronic lung disease. It is thought that the etiology is multifactorial. Decreased ventilatory control and hypo-responsiveness to hypoxia and […]
Definition Neonatal cardiac physiology differs from that of the adult in several ways. At birth, the neonatal myocyte is not fully developed; making the heart less able to respond to volume loading with an increased cardiac output. This is due to the higher proportion of fibrous tissue to contractile tissue, as compared to that of […]
Definition CPAP (Continous Positive Airway Pressure) provides continuous positive pressure which helps minimize atalectasis and maintain recruitment. In neonates, FRC is lower and closing volume (volume at which terminal airways are no longer open) is higher than in adults. Therefore CPAP is quite effective. Why nasal? Neonates are obligate nasal breathers (until 5 months of […]
Definition Neonatal hypoxemia is an inadequate oxygen level in the neonate to meet its metabolic demands. This may be different levels of oxygen depending on the age of the neonate. In utero, a normal partial pressure of oxygen from the umbilical artery is 20 mmhg (O2 saturation 40%) and the umbilical vein is 31 mmhg […]
Definition Neonatal bradycardia is defined as a decrease in heart by 30 bpm from baseline. Regarding neonatal resuscitation, bradycardia is concerning when the heart rate is less than 100 bpm. The primary cause of neonatal bradycardia is hypoxia. Other causes of bradycardia in this age group include hypothermia, hypovolemia, and pneumothorax, head injury, and medications. […]
Definition From 2-3 weeks of age, all infants (i.e., full-term and premature) in a warm environment respond to hypoxemia with a transient increase in ventilation followed by sustained ventilatory depression, however in infants born at 32 to 37 weeks, hyperpnea does not occur in a cool environment. By contrast, when pure oxygen is administered, ventilation initially decreases, followed by […]
Definition Negative pressure pulmonary edema (NPPE) is an uncommon complication of anesthesia usually resulting from laryngospasm during extubation (approximately 0.1%). The most common risk factors are young age, male sex, and head or neck surgery. NPPE is an example of a noncardiogenic pulmonary edema. In other words, pulmonary edema develops despite the fact that the […]
Definition Hepatitis B prophylaxis Current CDC guidelines call for the administration of hepatitis B immune globulin (HBIG) and/or hepatitis B vaccine. While the efficacy of the combination has not been evaluated in the needlestick injury setting, it has been shown to be the most efficacious approach in the perinatal setting. The approach has no contraindications during […]
Definition There is an FDA Black Box Warning on methadone which states, “In addition, cases of QT interval prolongation and serious arrhythmia (torsades de points) have been observed during treatment with methadone. Most cases involve patents being treated for pain with large, multiple daily doses of methadone, although cases have been reported in patients receiving doses commonly used for […]
Definition Together, can cause lactic acidosis However, this rare complication occurs only if the contrast medium causes renal failure, and the patient continues to take metformin in the presence of renal failure. Because metformin is excreted primarily by the kidneys, continued intake of metformin after the onset of renal failure results in a toxic accumulation of this […]
Definition Metabolic alkalosis is a very common primary acid–base disturbance associated with increased plasma HCO3. Increased extracellular HCO3 is due to net loss of H+ and/or addition of HCO3. The most common cause of metabolic alkalosis is gastrointestinal acid loss because of vomiting or nasogastric suctioning; the resulting hypovolemia leads to secretion of renin and aldosterone […]
Definition Arnold Chiari Malformation or Chiari II (CMII) is uniquely associated with myelomeningocele. Chiari II malformation is defined as the caudal herniation of the vermis, brainstem, and fourth ventricle through the foramen magnum[1] . The CM II was later found to be also associated with other abnormalities throughout the brain, skull, and spine. Hans Chiari […]
Definition Mediastinoscopy provides access to the mediastinal lymph nodes and is used to establish either the diagnosis or the resectability of intrathoracic malignancies. Anesthesia for mediastinoscopy involves multiple considerations. One frequent complication involves compression of the innominate artery by the scope. This can produce “apparent cardiac arrest” as subclavian flow is prevented. Because the innominate […]
Definition Mediastinal masses present special anesthetic considerations, as they can be associated with hemodynamic compromise from pulmonary artery and cardiac compression, neurologic problems (increased ICP, headache, and altered mental status) from obstructed venous drainage in the upper thorax (i.e. superior vena cava syndrome), or respiratory compromise from airway obstruction and loss of lung volumes. The most common masses […]
Definition EBV calculation: body wt (kg) x average blood volume (ml/kg) ABL= [EBV x (Hi-Hf)]/Hi Where: EBV=Estimated Blood Volume Hi= initial hemoglobin Hf= final hemoglobin Average blood volumes Premature Neonates 95 mL/kg Full Term Neonates 85 mL/kg Infants 80 mL/kg Adult Men 75 mL/kg Adult Women 65 mL/kg Normal Hct Values Men 42-52% Women 37-47% […]
Definition Maternal mortality is higher for women >35 years old, black patients, and patients without prenatal care. * Medical conditions exacerbated by pregnancy were primarily cardiovascular, pulmonary, and neurological diseases. Most deaths due to anesthesia occur during or after cesarean section with increased risk during emergency sections. Subspecialty Obstetric Anesthesia Related Media Keyword history […]
Definition General: Mannitol is an Osmotic diuretic 6 carbon sugar Dose: 0.25-1.0 g/kg Filtered at the glomerulus, but does not get significant reabsorption in the proximal tubule. This osmotically prevents passive water reabsorption that would occur with the active Na+ reabsorption in the proximal tubule Rapidly acting, therefore this acutely raises plasma/extracellular osmolarity Leads to […]
Definition Pre-Hospital Management of Acute Heart Failure EKG, spot BNP. Non-Invasive Positive Pressure Ventilation (NIPPV) for any patient in acute pulmonary edema. Pharmacology is based on systolic blood pressure Pharmacologic Management of Acute Heart Failure (in addition to NIPPV) SBP > 140 mm Hg: nitrates SBP 100-140 mm Hg: nitrates + furosemide SBP < 100 mm […]
Definition Central Core Disease is most associated w/ MH. More than Duchenne Muscular Dystrophy. Central Core Disease comes from a disorder on the same gene, RYR1 on chromosome 19. MD is x-linked recessive, risk for hyperK w/ sux leading to fatal Rhabdomolysis. Subspecialty General Related Media Keyword history 00%/0000 See Also: Sources PubMed
Definition Magnesium sulfate is used as a tocolytic and anticonvulsant in parturient patients with preeclampsa/eclampsia. Although it is a very effective medication in this setting it has severe adverse effects at supratherapeutic levels requiring regular monitoring of the patient for sign/symptoms of magnesium toxicity. Some minor side effects of magnesium are feeling warm/flushed, nausea or […]
Definition In vascular smooth muscle cells magnesium acts intracellularly and extracellularly as a calcium antagonist to inhibit contractility. In animal models it blocks calcium entry into these cells via voltage-and receptor-mediated channels. Inhibition of calcium entry into cells decreases the contractile actions of vasoactive agents. Intracellulary, calcium antagonism is related to the decreased influx and […]
Definition • Cardiac arrest • Pulmonary edema (lungs fill with fluid; can be fatal) • Chest pain • Cardiac conduction defects • Low blood pressure • Low calcium • Increased urinary calcium • Visual disturbances • Decreased bone density • Respiratory depression (difficulty breathing) • Muscular hyperexcitability Subspecialty General Related Media Keyword history 76%/2009 See […]
Definition Factors affecting MAC Significant hypoxia (below 40 mm Hg) decreases MAC. Hypothermia decreases MAC. Hyperthermia increases MAC. Hyperthyroidism slightly raises MAC (about 15%) Increasing age decreases MAC: Neonatal Halothane MAC: 1.1 70 y.o. MAC: 0.63 Circadian rhythms alter MAC + 10% Opioids reduce MAC, but there is a ceiling effect beyond which additional opioid […]
Definition LV filling occurs during diastole, which has 4 phases: (1) isovolumic relaxation; (2) rapid filling phase; (3) slow filling, or diastasis; and (4) final filling during atrial systole (atrial kick.) Cardiac Cycle Isovolumic relaxation – this phase occurs after the aortic valve closes and the mitral valve is still closed. LV relaxation is energy […]
Definition Diagnosis: Low cardiac output in the context of adequate filling pressures Treatment: Usually, LV dysfunction is amenable to inotropic therapy or combination therapy with positive inotropic and vasodilator agents to optimize cardiac output. Sympathomimetic amines (i.e., catecholamines such as epinephrine, norepinephrine, dopamine, and dobutamine) and phosphodiesterase inhibitors (e.g., milrinone) are commonly used as first-line therapy. Milrinone, […]
Definition ARDSNET Patients with ARDS (PaO2/FiO2 < 300, bilateral pulmonary infiltrates on a CXR, no clinical evidence of left atrial hypertension or if measured a wedge < 18 mm Hg, excluding all patients with elevated ICP, neuromuscular, sickle cell, or severe chronic respiratory disease, obesity > 1 kg/cm height, or burns > 30% of BSA) […]
Definition Conservative treatment is appropriate for most patients. This may include anti-inflammatory medications, physical therapy or chiropractic treatment, and avoiding activity that strains the neck or back. The majority of radiculopathy patients respond well to this conservative treatment, and symptoms often improve within 6 weeks to 3 months. Oxycodone, or oxycodeone with acetaminophen (Percocet) are often […]
Definition Stellate ganglion block (also called a cervicothoracic sympathetic block) is used primarily to treat Complex Regional Pain Syndrome, but has also been used to treat refractory angina, phantom limb pain and vascular insufficiency (such as Raynaud’s or frostbite),hyperhydrosis and other things. The stellate ganglion is formed by the fusion of the inferior cervical and first thoracic sympathetic ganglia anterior to the vertebral […]
Definition The lower extremity sensation is provided mainly by two major nerves: the sciatic (posterior) and femoral (anterior) nerves. The lumbar plexus consists of the ventral rami of L1-L4 with occasional contribution from T12. The lumbar plexus forms the lateral femoral cutaneous (L2-L3) which innervates the lateral thigh, femoral (L2-L4) innervating the anteromedial thigh and […]
Definition Definition: Tidal Volume (Vt) 4-7 cc/kg predicted body weight, i.e., [50 (male) OR 45 (female) +0.91(ht in cm – 152.4)] NHLBI: ARDS Network: Vt 6-8 cc/kg PBW AND Pplat <30 cm H20. PaO2 goal: 55-80mmHg. SpO2 goal: 88-95%. pH: 7.3-7.45. Rationale: Decreases incidence of Ventilator-Induced Lung Injury (VILI) – barotrauma, atelectato-trauma and volu-trauma secondary […]
Definition Local anesthetic toxicity can be seen in organs of the body that depend upon sodium channels for proper functioning. These include the central nervous system and heart. The CNS is more sensitive to the effects of local anesthetics than the cardiac system and will generally manifest signs/symptoms of toxicity first. Pharmacologic Data Effects on […]
Definition Lidocaine was first used as a spinal anesthetic in 1948. In 1991, case reports of cauda equina syndrome began to appear following the use of 5% lidocaine through microcatheters. Two years later, in 1993, transient neurologic symptoms (TNS), was described. TNS is a painful condition of the buttocks and thighs with possible radiation to the lower […]
Definition Methemoglobinemia can occur following use or prilocaine in adults. In adults, the toxic dose is ~ 600 mg IV. Prilocaine is metabolized by the liver to O-toluidine, which oxidizes hemoglobin (Fe2+) to methemoglobin (Fe3+). This can also occur with EMLA cream, especially in neonates 3 months or younger (although still safe in the vast majority of neonates). Treatment […]
Definition LMWH binds to anti-thrombin, a serine protease inhibitor, and creates a conformational change. This change accelerates its inhibition of activated factor X in conversion of prothrombin to thrombin. Thus,thrombin cannot convert fibrinogen to fibrin strands and clot formation. Once this change occurs LMWH is freed and can bind to another anti-thrombin molecules. LMWH also directly inhibits […]
Definition According to Miller, “Abnormalities in sodium electrolyte levels are frequently observed and are often related to volume status and sodium retention; these abnormalities can result in either hyponatremia or hypernatremia“. Other common abnormalities in ESLD include hyperkalemia, hypokalemia, and hypomagnesemia. During the liver transplant itself, hypocalecmia is extremely common during dissection and the anhepatic phases, but also due to chelation […]
Definition Most commonly injured lower extremity nerve in patients undergoing surgery in lithotomy position was the common peroneal nerve(L4-S2, represented 78% of nerve injuries in a study which looked retrospectively at 198,461 patients undergoing surgery in the lithotomy position). Etiology: Is thought to be secondary to compression of the nerve between the lateral head of the […]
Definition Introduction and Controversy Introduction to Liposuction and Tumescent Fluid Howard Solbel, in an editor’s response to Yoho’s article (see below), state the following – “Let us first understand the difference between the tumescent technique and the tumescent solution. The tumescent technique involves using the tumescent solution (lidocaine 0.05%, epinephrine 1:1,000,000) anywhere from 1:1 up […]
Definition Intro: Electrocution To receive a shock, persons need body contact with two separate conductive materials at different voltage potentials to complete a circuit. The most common scenario in which a shock occurs is where a grounded (“neutral voltage”) patient touches a “hot” wire which exists at a non-zero voltage potential – the electrical current […]
Definition Donor leukocytes (from pRBCs or platelets) are associated with potential adverse reactions. First of all, their HLA surface antigens are main targets of the recipient’s immune system and can cause febrile transfusion reactions in the recipients. Furthermore, some viruses such as CMV, HTLV 1, and EBV are transmitted in donor leukocytes. To prevent or at […]
Definition There are particular foods and fruits that are known to produce a type of substance that is similar to the rubber latex. This is known as the latex-fruit syndrome. Fruits (and seeds) involved in this syndrome include banana, pineapple, avocado, chestnut, kiwi fruit, mango, passionfruit, strawberry, and soy, as well as potato and bell pepper. […]
Definition Incidence of airway fire during laser surgery is traditionally quoted to be ~ 1%, although a large retrospective series of CO2 laser suggested that it may be closer to 0.1%. The data on PVC (clear) vs. red rubber tubes is conflicting. PVC absorbs CO2 lasers (and heats up), which are in the near infrared range, […]
Definition Laryngospasm treatment mandates immediate removal of the offending stimululs (suctioning) as well as the near-simultaneous application of 100% oxygen and positive pressure ventilation (to stent open the airway). Larson’s maneuver, a jaw thrust with bilateral pressure on the body of the mandible anterior to the mastoid process. If these fail, quickly deepend the anesthetic (using intravenous agents), followed […]
Definition Laryngospasm: Stimulation of vagus nerve during light anesthesia (Superior Laryngeal n, pharyngeal br of vagus, recurrent laryngeal below cords). Muscles involved: lateral cricoarytenoid, thyroarytenoids (both from recurrent laryngeal), crycrothyroid (from external branch of superior laryngeal). Causes: hypocalcemia, painful stimuli, vagal hypertonicity, foreign body. Airway Innvervation: The larynx is composed of nine cartilages, three paired and three unpaired and […]
Definition Laryngospasm is most commonly caused by anything that irritates the larynx, including secretions, blood, or debris. Nasal irritation, abdominal, buccal, pharyngeal stimulation, and even smell have been implicated. More likely when anesthesia is “light.” By definition lasts longer than the actual stimulus (this is a spasm). Common after upper airway procedures, particularly in children. Subspecialty Related […]
Definition The recurrent laryngeal nerve (RLN) and the superior laryngeal nerve (SLN) are branches of the vagus nerve (CN X). Injury to them may occur during thyroid surgeries. The SLN (external branch) innervates the cricothyroid muscle, which tenses and adducts the vocal cords. Injury to the nerve can produce changes in voice quality, but is […]
Definition Numerous conditions (i.e., infection, pregnancy, vestibular dysfunction, increased intracranial pressure) and exposures to various pharmaceuticals agents – including inhalational anesthetics – can cause nausea and vomiting. This complex series of reflexes is coordinated by the brainstem vomiting center, located in the lateral medullary reticular formation, and propagated chiefly via cranial nerves VIII and X […]
Definition Fick’s law of diffusion There are a number of factors that influence the rate of diffusion of gas through the alveolar/capillary interface, governed by Fick’s law of diffusion, which states that the volume of gas per unit time moving across the alveolar-capillary barrier is directly proportional to the surface area of the barrier, the […]
Definition Citrate is added to stored blood products, which prevents “in the bag” clotting by functioning as a calcium chelating agent. Citrate has the potential to cause two problems: metabolic alkalosis and hypocalcemia. Hypocalcemia due to citrate toxicity is more likely if 1) infusion of >50cc/min of blood products, 2) liver disease (unable to metabolize […]
Definition Lasers are devices that emit a single, coherent wavelength of electromagnetic radiation that is used to cut, coagulate or ablate tissue for a variety of clinical applications. The word LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. Lasers are comprised of an energy source, a resonant chamber, and an active medium, which can be in the gas, […]
Definition Nasal FOI can be done both awake and under general anesthesia. Awake Nasal FOI As with oral FOI, the key to success in an awake nasal fiberoptic intubation is adequate topical anesthesia. (And, as with anything in anesthesia, there is more than one way to do this procedure.) The nasal mucosa can be anesthetized […]
Definition Nalbuphine, 10 mg IM, produces analgesia with an onset of effect and duration similar to morphine. Depression of ventilation is similar to morphine until 30 mg IM of nalbuphine is exceeded, after which no further depression of ventilation occurs (ceiling effect). The plateau (ceiling) effect mechanism is due to nalbuphine’s partial agonist/antagonist properties and […]
Definition Entrance of nitrous oxide into cavities filled with gas (ex. bowel) can lead to an increase in pressure. After intravitreal injection of sulfur hexafluoride (colorless, odorless, non-flammable gas) or perfluoropropane (C3F8), nitrous oxide may increase intraocular pressure. This can be dangerous because ocular perfusion pressure (difference between arterial blood pressure and IOP) may be critically decreased. Regarding sulfur […]
Definition Myotonic dystrophy (MD) is a muscular disorder characterized by prolonged contraction and delay of relaxation of muscles, progressive muscle weakness, and wasting. Incidence is 1 in 8000 Signs and symptoms of MD1 include muscle weakness and wasting (especially in the cranial and distal limb musculature), myopathy, periodic myotonia, cardiac conduction abnormalities, insulin resistance, neuropsychiatric impairment, and cataracts (as well as […]
Definition The amount of oxygen consumed is determined by the basal O2 consumption, wall tension, contractility and heart rate. Wall tension =(pressureradius)/2wall thickness pressure = afterload; radius = preload Pressure alone is not a good measure for myocardial O2 consumption unless the other factors above are considered. The greater the contractility, the more oxygen the […]
Definition Caused by papillary rupture, acute MR can present itself with the following symptoms and signs. Symptoms/Signs: acute CHF, hypotension, increased pulmonary congestion. Increased Left atrium pressures because no time for left atrial compensatory mechanisms to occur and a V wave seen on the LAP, PAP, or PCWP tracing. On echocardiography, the LV and LA size […]
Definition Myasthenic syndrome and myasthenia gravis are two disorders of neuromuscular transmission that result in muscle weakness and fatigue. They differ in pathophysiology and their symptoms. Myasthenia gravis (MG) is an autoimmune disorder caused by circulating antibodies that block acetylcholine receptors at the postsynaptic neuromuscular junction (NMJ). MG has early signs of ocular and bulbar nerve involvement […]
Definition Myasthenia includes three groups of autoimmune disorders (myasthenia gravis, congenital myasthenic syndromes, Lambert-Eaton myasthenic syndromes) that affect the transmission of signals at the neuromuscular junctions that results in weakness and muscle fatiguability. With myasthenia gravis, ptosis, diplopia, dysphagia, and respiratory failure are often the initial symptoms. As the disease progresses, neck and limb-girdle muscle weakness […]
Definition Myasthenia gravis is caused by IgG antibodies to nicotinic ACh receptors. Most patients are on anticholinesterases, but may progress to steroids, thymectomy, immunosuppression, and plasmapheresis depending on the severity of the disease. IV immunoglobulin can be used for acute exacerbations. Because there are functionally fewer nicotinic receptors, patients with MG are less susceptible to succinylcholine and more susceptible to nondepolarizing […]
Definition Myasthenia gravis is an autoimmune disease that attacks post-synaptic nicotinic acetylcholine receptors at the NMJ. This leads to varying degrees of muscle weakness and fatigue and can affect ocular, bulbar (muscles involved in speech, chewing and swallowing), respiratory, and proximal skeletal muscles. Symptoms seem to be worse at the end of the day or […]
Definition Ensure that the patient is reminded prior to induction of the possibility of a prolonged intubation. Extubation: performed on awake patients and hopefully close to his/her baseline status. Reinstitute anticholinesterase medication, either by IV infusion or by reimplementation of the patient’s oral regimen. Leventhal criteria: Predictive scoring system for the need for postoperative ventilation 1) duration […]
Definition In the resting state, the electrical potential of the inside of a nerve cell is negative with respect with the outside. When the action potential depolarizes the nerve terminal, an influx of calcium diffuse into the cell via channels. The entry of calcium facilitates the release of acetylcholine (ACh). These ACh molecules then diffuse across […]
Definition Multiple Sclerosis is an autoimmune disease of inflammation, demyelination, and axonal damage to the central nervous system (Pasternak, 2008; Dorotta, 2002). The disease progression may be subacute with relapses and remissions or chronic and progressive. Treatments include corticosteroids, Interferon-beta, glatiramer acetate, azathioprine, and low-dose mexthotrexate. Although exacerbations can be triggered by physical and emotional stress, […]
According to Miller, “It has been speculated that general anesthesia and surgery may increase the risk for aggravation of MS. At present, there is no general consensus on this matter, and patients should therefore be informed of the potential for aggravated symptoms in the postoperative period” (p 1172), and “There has been no documented association […]
Definition Several factors contribute to the fact that morbidly obese patients are more prone to rapidly desaturate when apneic. Morbidly obese patients have increased oxygen demand, CO2 production, and alveolar ventilation, all because metabolic rate is proportional to body weight. Minute ventilation increases to maintain a normal CO2 level. Also, excessive adipose tissue over the chest decreases […]
Definition The predominant cause of worsened oxygenation in obesity is a reduction in functional residual capacity (FRC) and increased airway closure which essentially produces a right-to-left shunt. High FiO2 can contribute to this pathology by promoting atelectasis and further worsening shunting. BMI is correlated to the degree of both atelectasis and shunting. Anesthesia providers should endeavor to […]
Definition Barbiturate coma therapy has been used in head injured patients to lower ICP when other therapies such as mannitol and hyperventilation have failed. Barbiturates may also be protective during periods of cerebral hypoxia. The mechanism of action of barbiturates is by inhibiting the synaptic transmission thereby decreasing the cerebral metabolic rate of oxygen consumption, […]
Definition The ASA has produced guidelines that define levels of sedation. Minimal Sedation (Anxiolysis) is a drug-induced state during which patients respond normally to verbal commands.Example: Small amount of fentanyl or midazolam Moderate Sedation/Analgesia (“Conscious Sedation”) is a drug-induced depression of consciousness during which patients respond purposefully to verbal commands, either alone or accompanied by light tactile […]
Definition The general hemodynamic goal in treating mitral insufficiency is to preserve forward flow (and reduce regurgitant flow). Regurgitant flow decreases with decreasing size of regurgitant orifice, small pressure difference between LA and LV and duration of systole. This can be accomplished by maintenance of sinus rhythm, preload, inotropic state, afterload reduction, avoidance of bradycardia. […]
Definition Bypyridine derivative, isoenzyme fraction PDE III inhibitor. This inhibition decreases the hydrolysis of cAMP, leading to increased intracellular concentration of cAMP in the myocardium and vascular smooth muscle. Increased intracellular concentration of cAMP (little effect on cGMP) results in stimulation of protein kinases that phosphorylate substances responsible for uptake, storage, and release of Ca from sarcoplasmic reticulum during […]
Definition Drug Category: PDE inhibitor Mechanism: Causes direct stimulation of myocardial contractility and acceleration of myocardial relaxation. In addition, it causes balanced arterial and venous dilation with a consequent fall in systemic and pulmonary vascular resistances, and left and right heart filling pressures. Cardiac output increases due to the stimulation of myocardial contractility and the decrease […]
Definition Pediatric oral dose is 0.5 mg/kg. ACCORDING TO SMITH’S ANESTHESIA (CHAPTER 7), “times for peak serum concentrations after intramuscular, rectal, and oral administration were 15, 30, and 53 minutes, respectively, whereas the drug clearance and bioavailability via these three different routes were 10.4, 50.8, and 33.4 mL/kg per minute and 87%, 18%, and 27%, […]
Definition Bioavailability of IM, rectal, and PO routes are 87, 18, and 27%, respectively. According to Smith’s Anesthesia (Chapter 7), “times for peak serum concentrations after intramuscular, rectal, and oral administration were 15, 30, and 53 minutes, respectively, whereas the drug clearance and bioavailability via these three different routes were 10.4, 50.8, and 33.4 mL/kg […]
Definition Signs of malignant hyperthermia include increased CO2 production or minute ventilation, increased O2 consumption, increased cardiac output, increased HR, increased BP, arrhythmias, rigidity, and temperature elevation. MH is commonly associated with a mixed metabolic and respiratory acidosis on arterial blood gas. This is caused by increased lactic acid production coupled with inability to increase […]
Definition Methemoglobin (MetHb) is altered state of hemoglobin (Hb) in which the ferrous (Fe2+) irons of heme are oxidized to the ferric (Fe3+) state. The ferric hemes of MetHb are UNABLE to bind oxygen (O2). Thus, oxygen dissociation curve is left-shifted, making it more difficult to release O2. Methemoglobinemia types: Congenital – diminished enzymatic reduction […]
Definition Methemoglobin (MetHb) is altered state of hemoglobin (Hb) in which the ferrous (Fe2+) irons of heme are oxidized to the ferric (Fe3+) state. The ferric hemes of MetHb are UNABLE to bind oxygen (O2). Thus, oxygen dissociation curve is left-shifted, making it more difficult to release O2. Methemoglobinemia types: Congenital – diminished enzymatic reduction […]
Definition Myasthenic Syndrome (Lambert-Eaton) is caused by IgG antibodies to voltage-gated Ca++ channels in the musculature, which leads to increased sensitivity to both SCh and nondepolarizing muscle relaxants. Different from myasthenia gravis in both the type of muscles (proximal) and response to exercise (improvement with repetition, as opposed to increasing weakness in MG). Associated with […]
Definition Muscle Metabolism Muscle metabolism –> creatine –> creatinine (nonenzymatically converted). Creatinine production is constant, related to muscle mass (20-25 mg/kg males, 15-20 mg/kg females). Filtered but not reabsorbed in kidneys. Therefore, directly related to muscle mass, inversely related to glomerular filtration. More reliable than BUN because body muscle mass is fairly constant for a […]
Definition Most intravenous anesthetic agents increasing inhibatory through direct stimulation or potentiation GABA-mediated inhibatory tone. Ketanmine does NOT interact directly with the GABA recepror. Ketamine dose interacts with multiple other targets, including NMDA and non-NMDA glutamate receptors, nicotinic and muscarinic cholinergic, monoaminergic, and opioid receptors. In addition, interactions with voltage-dependent ion channels such as Na and L-type […]
Definition Ketamine is an NMDA-receptor antagonist that possesses intrinsic sympathomimetic activity. This effect is probably central in origin, although the precise mechanism is poorly understood. This sympathomimetic effect could increase myocardial oxygen demand and consumption. In a patient with pheochromocytoma this is especially undesirable, and could exacerbate pre-existing hypertension, precipitate congestive heart failure, cause myocardial […]
Definition Ketamine analgesic mechanism Drug Class: Phencyclidines How it differs from most other induction agents: In addition to being able to induce anesthesia, it also has significant analgesic properties Proposed analgesic benefits: Ketamine has been shown to inhibit nociceptive central hypersensitization. It also has been shown to reduce the incidence of acute tolerance after opioid […]
Definition Standards For Basic Anesthesic Monitoring (Last Amended October 25, 2005) Standard 1 Qualified anesthesia personnel should remain in the presence of the patient at all times during the administration of general anesthesia, regional anesthetics or monitored anesthesia care. Standard 2 During all anesthetics, the patient’s oxygenation, ventilation, circulation and temperature should be continually evaluated. […]
Definition Intravenous regional anesthesia involves the intravenous injection of local anesthetic distal to an occlusive tourniquet. It is often referred to as a Bier block since the first documented use was by August Bier in 1908. Although it is most commonly employed for surgery on the upper extremity, it has been done on the lower […]
Definition The body responds to acute blood loss with four basic compensatory mechanisms. Knowledge of these mechanisms allows physicians to adequately assess for the need for blood transfusion. The first response is increased cardiac output. Stroke volume increases due to decreased systemic vascular resistance (SVR). SVR decreases due to the diminished viscosity of the blood. […]
Definition All inhalational agents, including isoflurane, decrease cerebral metabolic rate of oxygen (CMRO2). It is known that isoflurane can cause burst-suppression as well. The CMRO2-decreasing effect does not seem to be significantly different between isoflurane, sevoflurane, and desflurane. All intravenous induction agents, except ketamine, decrease CMRO2 but preserve CMRO2 – cerebral blood flow (CBF) coupling […]
Definition Pierre Robin Sequence (PRS) is a collection of physical characteristics of a newborn that includes micrognathia (small jaw), glossoptosis (tongue falls to back of throat), and airway obstruction. The incidence of PRS varies from 1:5000-1:85,000. Although most patients with PRS have a cleft palate, it is not a requirement for the diagnosis. Pierre Robin […]
Definition Hyperventilation by positive pressure ventilation can lead to oliguria through a number of different mechanisms: 1) Decreased cardiac output secondary to the increased intrathoracic pressure and an increase in right ventricular afterload – the decrease of cardiac output and BP caused by PPV results in a baroreceptor mediated increase in SNS with subsequent renal […]
Definition Key Points Some patients develop the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) after SAH and are appropriately managed with fluid restriction. SIADH, which is characterized by normovolemia or mild hypervolemia, is treated by volume restriction. However, hyponatremia after SAH is more likely to be the result of the cerebral salt-wasting syndrome, which […]
Definition This keyword refers to the phenomenon of distal pulse amplification. When blood pressure is measured arterially from multiple sites simultaneously, the morphology of the signal changes dependent upon changing characteristics of the vascular tree. As the waveform is measured further from the aorta, the systolic peak becomes higher, the end-diastolic pressure becomes lower, and […]
Definition Nitrous oxide is 34 times more soluble than nitrogen. Therefore, nitrous dissolves into an air pocket much faster than nitrogen dissolves out leading to an expansion of the air pocket. This is bad in some cases: cases in which the air space is closed off, such as the following: Clinical Scenarios in Which Nitrous […]
Definition An ipsilateral phrenic nerve block occurs in almost 100% and leads to a 25% reduction in pulmonary function. This procedure is therefore contraindicated in anyone with respiratory insufficiency or a contralateral nerve palsy. Risk of pneumothorax is remote but real. Recurrent laryngeal nerve is occasionally blocked as well, and this can lead to hoarseness […]
Definition Complications include: Ipsilateral phrenic nerve block resulting in diaphragmatic paresis occurs in 100% of patients undergoing interscalene blockade, even with dilute solutions of local anesthetics, and is associated with a 25% reduction in pulmonary function. Involvement of the vagus, recurrent laryngeal, and cervical sympathetic nerves is rarely significant, but a patient experiencing symptoms related […]
Definition Anatomy The interscalene nerve block is performed at the C6 level (level of the cricoid cartilage) between the anterior and middle scalene muscles. 1) Place the patient supine with head turned to the opposite side to be blocked. 2) Identify the sternocleidomastoid. By having the patient slightly raise his head, the scalene muscles behind […]
Definition Vapor Pressure of Inhaled Anesthetic Agents (at 20 C) Desflurane: 669 mm Hg Halothane: 243 mm Hg Isoflurane: 238 mm Hg Sevoflurane: 157 mm Hg Blood:Gas Partition Coefficient of Inhaled Anesthetic Agents (at 20 C) Halothane: 2.50 (MAC 0.75%) Isoflurane: 1.46 (MAC 1.2%) Sevoflurane: 0.65 (MAC 1.8-2.4%) Desflurane: 0.42 (MAC 6-7.2%) Subspecialty General Related […]
Definition All volatile halogenated agents cause dose-related relaxation of the uterus which may lead to increased blood loss during cesarean section. From induction to delivery of the infant 1.0 MAC is given to avoid maternal awareness. After delivery, volatile anesthetics are decreased to 0.5 – 0.75 MAC and oxytocin is given concurrently to decrease the […]
Definition Inhaled anesthetics are delivered and eliminated via pulmonary ventilation. The most useful definition of “dose” for these drugs is the partial pressure in alveolar gases, which is readily monitored in end-tidal expired gases. Volatile anesthetics tend to increase respiratory rate, decrease tidal volume, and blunt ventilatory responses to hypercapnia and hypoxia. Volatile anesthetics depress […]
Definition There is agreement among most institutions that ingestion of clear fluids 2–3 h prior to general anesthesia is acceptable. Most also accept a 4 hour restriction for breast milk and a 6 hour restriction for nonhuman formula. There is great diversity among institutions regarding fasting for solids in children, with many restricting intake after […]
Definition The utmost concern in managing patients with increased intracranial pressure (ICP) is to maintain cerebral perfusion and oxygenation. Therefore, emphasis should be placed upon the avoidance of cerebral ischemia and hypoxia when choosing anesthetic induction agents. Understanding the pathophysiology of cerebral hypertension and the systemic/cerebral physiological effects of induction agents is far more important […]
Definition Any obstruction to outflow can potentially lead to increased airway pressure, reduced minute ventilation, lung hyperinflation, and subsequent cardiopulmonary effects (ex. hypotension due to decreased venous return, lung injury due to volutrauma/barotrauma). The capnograph may show a prolonged expiratory upstroke (similar to in COPD) An expiratory valve stuck in the open position may be […]
Definition Placed in patients with VF or VT, long QT, HOCM (if VT or VF), post-MI (if EF < 30%), dilated cardiomyopathy. When a magnet is placed some will beep or emit continuous tone signifying anti-tachycardia function is disabled. Magnets usually do not effect anti-bradicardia functions. Different manufacturers’ devices respond slightly differently to magnet (hence […]
Definition According to Barash, IHSS (HoCM) treatments include : alcohol ablation of the interventricular septum Pacing, using mode DDD with a short AV delay. This pre-excites the LV apex, resulting in paradoxical septal motion. The result is decreased ejection velocity, no SAM, and reduced LVOT gradient. septal myomectomy Goals include : myocardial depression, often with volatiles preload […]
Definition Prognosis If the LV wall is > 30mm, the incidence of Sudden Cardiac Death is 2% per year. Diastolic dysfunction is more common than systolic outflow obstruction. Medical Treatment Consider treating with beta-blockers, calcium antagonists, or disopyramide (Class IA antiarrhythmic, i.e. sodium channel blocker) to reduce dynamic LVOT obstruction. Intraoperative Considerations Anesthetic goals should […]
Definition Anti-IgA antibodies have been identified in severely IgA deficient patients who experienced infusion reactions to blood products containing small amounts of IgA, typically in plasma, including the following: whole blood, RBCs, plts, FFP, cryoprecipitate, granulocytes, IVIG It is suggested that screening for anti-IgA antibodies in all patients with severe IgA deficiency and for patients […]
Definition While the mantra “if the gut works, use it” is still widely held to be true, data do not fully support any of the purported advantages of enteral over parenteral nutrition with the exception of lower cost. The concept of bacterial translocation and its minimization by using the intestinal tract is based almost entirely […]
Definition The process by which intracranial tumors produce cerebral compression was initially described over one hundred years ago. (Source 1) In the normal adult, intracranial contents (i.e. cellular mass, blood, and CSF) have a combined volume of 1200-1500 cm^3. (Source 2). The presence of a tumor (or other mass lesion, e.g. hematoma) increases intracranial volume. […]
Definition Indications: patients with hemodynamic instability or severe LV systolic dysfunction. Contraindications: Severe peripheral vascular disease (PVD) of the aortoiliac and femoral arteries – due to increased risk of lower extremity ischemia. Severe aortic valve insufficiency (AI), because their AI will be worsened by the balloon pump. Keyword history 86%/2010 92%/2017 See Also: Keys to […]
Definition For information on Hypoxic Pulmonic Vasoconstriction, see Hypoxic Pulmonary Vasoconstriction While Hypoxic Pulmonary Vasoconstriction is a well-described phenomena, mammalian lungs may be capable of vasodilating following a hypoxemic challenge (pO2 < 25 mm Hg). It is thought that this response is mediated by adenosine [Gottlieb JE et al. Am J Physiol 247: H541, 1984]. […]
Definition Adapted from Miller, Table 59-19, treatment for gradual desaturation during one lung ventilation: Increase FiO2 to 100% PEEP to ventilated lung CPAP to nonventilated lung Restrict blood flow to nonventilated lung (clamp pulmonary artery) Subspecialty General Related Media Keyword history 90%/2010 See Also: Sources Slinger PD, Campos JH. Anesthesia for Thoracic Surgery. Chapter 59. […]
Definition Etiology Causes of Hypoxia Inadequate Oxygen Delivery: inadequate minute ventilation or FiO2; mechanical failure, disconnect R-L Shunt: intracardiac shunting V/Q Mismatch: mainstem, pulmonary edema, aspiration, atelectasis, pulmonary embolus Impaired Diffusion: pulmonary edema, pneumonia Note that despite the separate classifications above, most cardiopulmonary pathology contributes to hypoxemia via multiple mechanisms (ex. emphysema causes hypoventilation, diffusion […]
Definition Hypotension is a late finding in pediatric patients (children may maintain a normal blood pressure until 35% of blood volume is lost). Tachycardia is sensitive but not specific indicator. Prolonged capillary refill (> 2 seconds), especially when combined with tachycardia, is more specific, although it may be difficult to measure. Cold skin and decreased […]
Definition pH-Stat During pH-stat acid-base management, the patient’s pH is maintained at a constant level by managing pH at the patient’s temperature. pH-stat pH management is temperature-corrected. Compared to alpha-stat, pH stat (which aims for a pCO2 of 40 and pH of 7.40 at the patient’s actual temperature) leads to higher pCO2 (respiratory acidosis), and […]
Definition In humans, heat (or “thermal energy”) is more concentrated in the core than it is in the extremities. This is why your hands or feet may be cold even though you core is normothermic. Thus, the core temperature may be 37 but the mean body temperature might be 36 or 35.5. General anesthesia (and […]
Definition Hypocalcemia typically prolongs the Q-T interval on electrocardiograms and may lead to complete heart block. Other signs and symptoms include mental status changes, tetany, laryngospasm, Chvostek (facial nerve) and Trousseau (brachial artery occlusion) signs, hypotension, and arrhythmias. Hypercalcemia (increased serum calcium) produces a quicker ventricular repolarization and therefore shorter Q-T interval. Hypocalemia Cardiac: prolonged […]
Definition Hyperthyroidism results from excess synthesis and release of thyroid hormone SYMPTOMS Nervousness Anxiety Increased perspiration Heat intolerance Tremor Hyperactivity Palpitations Weight loss despite increased appetite Reduction in menstrual flow or oligomenorrhea SIGNS Hyperactivity Tachycardia or atrial arrhythmia Systolic hypertension Warm, moist, and smooth skin Lid lag Stare Tremor Muscle weakness Subspecialty General Keyword history […]
Definition Irritation of the pons, medulla, or 5th cranial nerve can lead to bradycardia or tachycardia, hypotension or hypertension, and arrhythmia. During brainstem surgery close monitoring of EKG and arterial pressure is necessary. Subspecialty Neuroanesthesia Related Media Keyword history 73%/2008 See Also: Sources Irritation of the pons, medulla, or 5th cranial nerve can lead to […]
Definition Irritation of the pons, medulla, or 5th cranial nerve can lead to bradycardia or tachycardia, hypotension or hypertension, and arrhythmia. During brainstem surgery close monitoring of EKG and arterial pressure is necessary. Subspecialty Neuroanesthesia Related Media Keyword history 73%/2008 See Also: Sources Miller’s Anesthesia, 7th Edition. Chapter 63 PubMed
Definition Epidemiology: Primary hyperparathyroidism occurs in about 0.1% of the population, most commonly begins in the third to fifth decades of life, and occurs two to three times more frequently in women than men. Etiology: Primary hyperparathyroidism usually results from enlargement of a single gland, commonly an adenoma and very rarely a carcinoma. Hypercalcemia almost […]
Definition Increases in plasma magnesium are often due to excessive intake (magnesium-containing antacids or laxatives) and/or renal impairment. Iatrogenic hypermagnesemia can also occur during magnesium sulfate therapy for gestational hypertension in the mother as well as the fetus. Less common causes include adrenal insufficiency, hypothyroidism, rhabdomyolysis, and lithium administration. Clinical manifestations typically are hyporeflexia, sedation, […]
Definition Physiologic antagonists: 500 mg calcium chloride, or 1 gm calcium gluconate is enough to temporarily stabilize the heart from the effects of hyperkalemia Shift K+ from plasma back into the cell: intravenous glucose (25 to 50 g dextrose, or 1-2 amps D50) plus 5-10 U regular insulin will reduce serum potassium levels within 10 […]
Definition Physiologic antagonists: 500 mg calcium chloride, or 1 gm calcium gluconate is enough to temporarily stabilize the heart from the effects of hyperkalemia Shift K+ from plasma back into the cell: intravenous glucose (25 to 50 g dextrose, or 1-2 amps D50) plus 5-10 U regular insulin will reduce serum potassium levels within 10 […]
Definition Normal p50 is 27 mm Hg. Several factors can cause a right shift (increased unloading) in the oxyhemoglobin dissociation curve – acidemia, hypercarbia, increased temperature, and increased 2,3-DPG (all of which are more effective during hypoxemia, ex. at tissue levels). Changes in pH and pCO2 generally go hand-in-hand. This is know as the Bohr […]
Definition Alveolar Gas Equation pAO2 = FiO2 (Patm – pH20) – paCO2/RQ It is important to note than any increase in CO2 must result in a decrease in the pAO2. As an example, if FiO2 is 0.21 at sea level (pH2O is 47 mm Hg and RQ is 0.8), as PaCO2 rises from 40 to […]
Definition Symptoms: mild to moderate hypercalcemia (11 to 14 mg/100 mL) often has no symptoms, but when levels > 15 mg/100 mL, clinical changes become more common Hypercalcemia produces changes primarily in the central nervous system (e.g., mental status changes), the gastrointestinal tract (e.g., vomiting), the kidneys (e.g., polyuria, renal calculi, oliguric renal failure), and […]
Definition Hyperbaric oxygen (HBO) is when oxygen is delivered in an environment where the barometric pressure is more than 1 atmosphere. This is common therapy for arterial air embolism, decompression sickness, severe profound anemia or hypoperfusion, severe CO poisoning, and gas gangrene from C. perfringens. There are some fundamental gas laws to be aware of […]
Definition Hydrochlorothiazide is a thiazide class diuretic that works by inhibiting the kidney’s ability to retain water. It is also thought to directly decrease peripheral vascular resistance via another mechanism. Specifically, thiazides inhibit sodium reabsorption at the distal convoluted tubule, promoting naturesis and water loss. Like loop diuretics (which block reabsorption in the ascending tubule) […]
Definition Epinephrine (adrenal medulla) and norepinephrine (nerve endings) are released by the sympathetic nerve system and result in gluconeogenesis, glycogenolysis, lipolysis, and glucagon release (in addition to their hemodynamic effects). Cortisol (release from the adrenal cortex) also leads to gluconeogenesis, adipocyte sensitization (to growth hormone and catecholamines), blocks the anti-proteolytic actions of insulin, and also […]
Definition Key Points In patients with HOCM, systolic septal bulging into the LVOT, malposition of the anterior papillary muscle, drag forces, and hyperdynamic LV contraction (causing a Venturi effect) may contribute to creation of a LVOT gradient. This type of obstruction is dynamic and is accentuated by any intervention that reduces ventricular size. Therefore, increases […]
Definition Incidence/Mortality Estimated to occur in 3-10% of orthopedic trauma patients. Mortality is 10-20% Pathophysiology Theory #1 (mechanical): large fat droplets are released into the venous system. These droplets are deposited in the pulmonary capillary beds and travel through arteriovenous shunts to the brain. Microvascular lodging of droplets produces local ischemia and inflammation, with concomitant […]
Definition Hydroxyethyl starch (hetastarch) is a colloid solution available in the United States as a 6% solution in 0.9% NaCl (Hespan), as well as Hextend. The larger molecules (the range is from 10,000 to 2 million daltons) of Hespan are degraded by amylase. Hydroxyethyl starch is stored in the reticuloendothelial system for hours and is […]
Definition Maternal primary infection with HSV before pregnancy does not usually impact the intrauterine development of the fetus. Increased rates of miscarriage and IUGR following primary HSV infection during pregnancy have been reported. Intrauterine HSV infections are rare (1 in 200,000 deliveries). Manifestations in such cases include skin vesicles, eye disease, microcephaly or hydranencephaly. The […]
Definition Garlic lowers blood pressure, lipid levels, and thrombus formation, in addition to inhibiting platelet aggregation through a variety of mechanisms (important components include alliin, allicin, and ajoene, the latter of which may potentiate other platelet inhibitors). Effects of Garlic Potentially irreversible platelet inhibition Reduced blood pressure Decreased lipid levels Reduced thrombus formation Subspecialty General […]
Definition Garlic is used for its potential to prevent atherosclerosis by reducing blood pressure, thrombus formation, and serum lipid and cholesterol levels. The development of concentrated garlic preparations has made it possible for patients to take otherwise unachievable high doses, which may increase the risk of adverse effects. The pharmacologic effects of garlic are primarily […]
Definition Heparin is a highly sulfated glycosaminoglycan which is widely used as an injectable anticoagulant. Heparin binds to antithrombin III causing a conformational change that results in its activation through an increase in the flexibility of its reactive site loop. The activated antithrombin III then inactivates thrombin and other proteases involved in blood clotting, most […]
Definition 3000 mg of bilirubin is formed daily, 75% of which is from heme metabolism and 25% of which is from other proteins (ex. cytochrome P450) Normal Bilirubin Levels Total: 0.1-1.9 mg/dL (depending on the source) Conjugated: 0-0.4 mg/dL (also depending on the source) What is bilirubin? – bile pigment, a physiological product of heme […]
Definition Direct laryngoscopy and tracheal intubation in patients with normal protective airway reflexes results in stimulation of the sympathetic nervous system. This, in turn, may lead to hemodynamic changes such as increased HR, elevated systolic BP, and cardiac arrhythmias (especially ventricular bigeminy). In the study below [image and citation needed], a comparison in healthy normotensive […]
Definition The process of HD involves a dialyzer which contains semipermeable membrane with microscopic holes that allow only some substances to cross. Dialysate, also called dialysis fluid, is a solution of pure water, electrolytes and salts, such as bicarbonate and sodium, passes through one side of the membrane while blood from patients circulate through the […]
Definition Acute effects: hypotension (too much fluid removed), “dialysis disequilibrium” (rapid fluid/urea shifts resulting in cerebral edema – headache, nausea, can progress to convulsions and coma) hypercalcemia, fever, arrhythmias (due to hypokalemia, especially in patients on digoxin,) bleeding (due to heparinization.) Chronic effects: hepatitis (B more common than C, due to frequent blood transfusions), anemia, […]
Definition Gas flow through a tube is either laminar (parabolic velocity profile) or turbulent (flat velocity profile). The nature of flow is dependent on several physical properties of the gas (density, viscosity) as well as of the flow itself (velocity, length of tubing), all of which can be combined mathematically into the Reynold’s number, Re […]
Definition Heliox (70% helium, 30% oxygen) therefore affects gas flow in two ways – first, the Reynold’s number is lower (because density is lower), and thus flow is more likely to be laminar, and second, if flow IS turbulent, resistance to flow will be lower, becuase Heliox is less dense (~ 0.5 g/L versus 1.2 […]
Definition The transplanted heart will not be able to respond to drugs that act by blocking the parasympathetic system because these connections were severed during the transplant. Therefore, treating bradycardia would have to be done with agents such as isoproterenol, glucagon, epinephrine, norepinephrine (drugs that have a direct effect on the heart). Isoproterenol is most […]
Definition Complete heart block is most commonly caused by myocardial infarction. An inferior wall MI (RCA in 85% of population) can damage the AV node, leading to complete heart block. An anterior wall MI (LAD) can damage the distal conducting system, also preventing atrial-ventricular communication. Note that the sinus node artery is from the RCA […]
Definition Respiratory Effects a. Increases Atelectasis: leads to decreases in FRC, causing 1)cephalad displacemnent of diaphragm, 2)weight of abdominal contents on diaphragm, 3)increased central blood volume b. Increased work of breathing secondary to increased impedance to stretching of chest wall and diaphragm c. Movement of the ETT: cephalad movement of diaphragm can shift carina carina […]
Definition Hydrochlorothiazide is a sulfonamide derivative. It blocks the Na/Cl co-transporter in the early segment of the distal convoluted tubule. Thiazides INCREASE calcium levels in the blood. Other side effects include : hypokalemia, hypochloremic metabolic alkalosis, hyperuricemia, hyperglycemia, hyponatremia. Subspecialty General Related Media Keyword history 52%/2008 See Also: ABA:Hydrochlorothiazide – Blood chemistry effects Sources PubMed
Definition Deoxygenated blood can carry increasing amounts of carbon dioxide, whereas oxygenated blood has a reduced carbon dioxide capacity. The Haldane Effect describes the effect of oxygen on CO2 transport. The Haldane Effect (along with the Bohr Effect) facilitates the release of O2 at the tissues and the uptake of O2 at the lungs. This is […]
Definition There are two known histamine receptors, designated H1 and H2. H1 receptor antagonists are typically utilized to suppress the body’s histamine-mediated effects in anaphylactoid or anaphylactic reactions. H2 antagonists are competitive antagonists at the parietal cell H2 receptor, and are typically used to suppress gastric acid secretion. H2 blockers begin working within an hour, […]
Definition The GCS is the summation of scores for eye, verbal, and motor responses. The minimum score is a 3 which indicates deep coma or a brain-dead state. The maximum is 15 which indicates a fully awake patient (the original maximum was 14, but the score has since been modified). For best eye responses, there […]
Definition Ventilatory responses to hypoxia, hypercapnia, and stress are reduced, while the depressant effects of both intravenous agents (benzodiazepines, opioids) and volatile anesthetics are more pronounced. Elastic recoil is lost and surfactant is reduced, leading to an increase in lung compliance. These, combined with a loss of alveolar surface area leads to increased anatomic dead […]
Definition According to Miller, “age does not significantly affect the pharmacodynamics of muscle relaxants… Duration of action may be prolonged, however, if the drug depends on liver or renal metabolism.” There is approximately a 1% per year reduction in cardiac output after 30 years of age, and a reduction in cardiac output would result in […]
Definition Elderly lungs lose tissue elasticity and demonstrate increases in lung compliance (much like emphysema), however, chest wall compliance decreases, so the net pulmonary compliance is virtually unchanged. Breakdown of alveolar septae increases anatomic and alveolar dead space and increases ventilation- perfusion mismatch. Shunting and physiologic dead space also increase. Closing capacity becomes greater than […]
Definition Classically it has been taught that patients who are at a higher risk of aspiration include those who have a “full stomach,” diabetic patients, patients with hiatal hernia or GERD, patients with cirrhosis, patients with significant ESRD, and pregnant patients. Warner’s landmark study noted that emergency surgery and higher ASA score were independent predictors, […]
Definition Gas Laws: temperature/pressure changes PV=NRT where k is the Boltzmann constant. N is the number of molecules. These equations are exact only for an ideal gas, which neglects various intermolecular effects.However, the ideal gas law is a good approximation for most gases under moderate pressure and temperature. This law has the following important consequences: […]
Definition Subspecialty General Related Media Ask the Experts (March 2011) with Dr. Peter Slinger on thoracic anesthesia, one-lung ventilation, anterior mediastinal masses Keyword history 66%/2008 See Also: ABA:Mediastinal tumor – Airway obstruction Sources PubMed
Definition The lung volume at the end of a normal exhalation is called functional residual capacity (FRC). At this volume, the inward elastic recoil of the lung approximates the outward elastic recoil of the chest (including resting diaphragmatic tone). Thus, the elastic properties of both chest and lung define the point from which normal breathing […]
Functional Residual Capacity is the amount of volume remaining in the lung after a normal exhalation. Lung Volumes: TLC = Total Lung Capacity VC = Vital Capacity IC = Inspiratory Capacity FRC = Functional Residual Capacity Vt = Tidal Volume RV = Residual Volume ERV = Expiratory Reserve Volume IRV = Inspiratory Reserve Volume Dependent […]
Definition Foot and toe surgery can be successfully performed with an ankle block. There are five peripheral nerves that innervate the foot: Tibial, Deep peroneal, superficial peroneal, sural, and saphenous. They all derived from the sciatic nerve with the exception of the saphenous which is derived from the femoral nerve. At the ankle, the 2 […]
Definition Flow through a tube can be described by the modified Bernoulli Equation, which states: Po = P + 1/2 ρ*U^2 Where Po is a constant called the “stagnation pressure,” P is pressure, ρ is density, U and is equal to fluid velocity. Pressure does not always decrease in the direction of flow – if […]
Definition Common Hypothyroidism Polymyalgia rheumatica Autoimmune disorders (Rheumatoid arthritis, SLE) Sjogren’s syndrome Less common Hepatitis C Sleep apnea Chiari malformation Celiac sprue Subspecialty Pain and Regional Anesthesia Related Media Keyword history 86%/2011 See Also: Sources Clauw DJ. Fibromyalgia. In: Fishman, S. & Ballantyne, J. & Rathmell, J. (2010). BONICA’S MANAGEMENT OF PAIN (4th). Philadelphia, PA; […]
Definition Replacement of Isolated Factor Deficiencies FFP is efficacious for treatment of deficiencies of factors II, V, VII, IX, X, and XI when specific component therapy is neither available nor appropriate. Requirements for FFP vary with the specific factor being replaced. For example, hemostatic levels of factor IX in a patient with severe deficiency are […]
Definition 90% of the citrate found in whole blood products is found in FFP and platelets (not PRBCs). Citrate chelates calcium (and magensium) (that is why it is used, to prevent clotting of store blood products) and this is the mechanism of citrate intoxication. Signs and symptoms of hypocalcemia (whether or not caused by citrate) […]
Definition Fetal heart rate monitoring is done either externally by a Doppler ultrasound monitor attached to the mother’s abdomen, or internally by elecrocardiography monitor attached to the fetus’ presenting part. Internal, or direct monitoring, requires rupture of membranes and cervical dilation of at least 1.5 cm. A normal fetal heart rate tracing is characterized by: […]
Definition Maternal hypotension has been associated with fetal bradycardia in multiple settings. Subspecialty Obstetric Anesthesia Related Media Keyword history 76%/2010 See Also: Sources PubMed M Ron, H Yaffe, W Z Polishuk Fetal heart rate response to maternal hypotension during amniocentesis. Int J Gynaecol Obstet: 1976, 14(6);503-4 [PubMed:20348] H S DOWNS, P H MORRISON THE EFFECTS […]
Definition Oxygen travels in the blood as a soluble gas or bound to hemoglobin. A significantly larger portion of oxygen is bound to hemoglobin and a relatively smaller portion is dissolved in blood. This is characterized best by examining the formula for oxygen content in arterial blood [CaO2=(1.34 x hb x O2 sat) + 0.003 […]
Definition pH 7.34-7.40, PaO2 65-85, PaCO2 30-36, RR 35 Note that tidal volume is the same for all ages (including adults) at 6 ml/kg. Alveolar ventilation, however drops from 130 ml/kg/min to 60 ml/kg/min in an adult. Subspecialty Obstetric Anesthesia Related Media Keyword history 78%/2009 See Also: Sources Stoelting Basics of Anesthesia, ed 5 pp […]
Definition Fenoldopam is a selective DA1-receptor agonist that has many of the benefits of DA but with little or no alpha or beta adrenoceptor or DA2-receptor agonist activity. Fenoldopam has been shown to exert hypotensive effects characterized by a decrease in peripheral vascular resistance, along with an increase in renal blood flow, diuresis, and natriuresis. […]
Definition The fractional excretion of sodium, or FENA, is a calculated value used in the assessment of acute renal failure. It is an assessment of how much sodium is being excreted in the urine in comparison to how much total sodium the kidneys are “seeing” in the plasma. It is essentially a measure of how […]
Definition Relevant Anatomy Femoral nerve (posterior divisions of L2-4) is formed in the psoas major muscle, runs between psoas and iliacus muscles and enters the thigh under the inguinal ligament lateral to the femoral artery, at which point it divides into multiple terminal branches (usually classified as anterior [mostly cutaneous] and posterior [mostly motor]). Landmarks […]
Definition Occur in 0.5% of RBC transfusions and 30% of platelet transfusions. Febrile reaction may occur without hemolysis. Recipient antibodies directed against HLA antigens on donor WBCs or platelets are the most common cause, although cytokines released from WBCs of stored products (particularly platelets) may also be a cause. Relatively common in multitransfused or multiparous […]
Definition Occur in 0.5% of RBC transfusions and 30% of platelet transfusions. Febrile reaction may occur without hemolysis. Recipient antibodies directed against HLA antigens on donor WBCs or platelets are the most common cause, although cytokines released from WBCs of stored products (particularly platelets) may also be a cause. Relatively common in multitransfused or multiparous […]
Definition Incidence/Mortality Estimated to occur in 3-10% of orthopedic trauma patients. Mortality is 10-20% Pathophysiology Theory #1 (mechanical): large fat droplets are released into the venous system. These droplets are deposited in the pulmonary capillary beds and travel through arteriovenous shunts to the brain. Microvascular lodging of droplets produces local ischemia and inflammation, with concomitant […]
Definition Incidence/Mortality Estimated to occur in 3-10% of orthopedic trauma patients. Mortality is 10-20% Pathophysiology Theory #1 (mechanical): large fat droplets are released into the venous system. These droplets are deposited in the pulmonary capillary beds and travel through arteriovenous shunts to the brain. Microvascular lodging of droplets produces local ischemia and inflammation, with concomitant […]
Definition Drugs 1. Antibiotics Aminoglycosides: Gentamicin & Tobramycin Tetracyclines Polymixins The following antibiotics do not prolong neuromuscular blockade: Erythromycin, penicillin, and cephalosporins. 2. Anticholinesterases 3. Calcium Channel Blockers 4. Local Anesthetics 5. Volatile Anesthetics Abnormal Physiologic States Hepatic Dysfunction Hypothermia Acidosis or Alkalosis Electrolyte Abnormalities Hypernatremia Hypocalcemia Hypokalemia Lithium User: Bassam Kadry, 19:19, 11 July […]
Definition Turbulent gas flow increases with increasing gas density and gas flow rate. Decreasing gas density with heliox (molecular weight 9.6) instead of air (molecular weight 29) to ventilate patients helps to relieve airway obstruction e.g. in tracheal stenosis. Decreasing gas flow rate, as in taking slower deep breaths, also helps to ventilate patients with […]
Definition Massive Blood Loss/Transfusion 30% of factor VIII are needed for adequate hemostasis during surgery. Packed RBCs have very few coagulation factors. That said, factor VIII (and factor V) rarely decreases below levels required for hemostasis, even after massive transfusion. According to Miller, “low factors V and VIII appear to be an unlikely primary cause […]
Definition Also known as acquired Hemophillia A Treat bleeding and its complications If titer < 5 BU, try human FVIII infusions, aiming for plasma levels of 30– 50% If titer > 5 BU, begin with rVIIa at a dose of 90–120 μg/kg IV q 3 hours. Follow clinical response. If still bleeding, should use activated […]
Definition Most common hereditary hypercoagulable state: 4-8% population Gene causes change in Factor V protein making it resistant to inactivation by protein C –> increased propensity to clot by increased Factor V concentrations in blood Long term homozygotes for Factor V Leiden will receive anticoagulation Must weigh risks of anticoagulation vs risk thrombosis Treatment length […]
Definition The ex utero intrapartum treatment (EXIT procedure) involves partial delivery of the infant and maintenance of uteroplacental circulation long enough to secure the airway and provide potentially lifesaving interventions (bronchoscopy, tracheostomy, cannulation for ECMO) based on the condition of the neonate. It was initially used for patients diagnosed with congenital diaphragmatic hernias in utero, […]
Definition Common problems associated with prematurity include respiratory distress syndrome, apnea, hypoglycemia, hypocalcemia, hypomagnesemia, hyperbilirubinemia. The major pulmonary complication found in former-premature infants is post-operative apnea– post-operative apnea is a serious concern in the neonate, particularly if there is a history of prematurity, prior apneic episodes, bradycardia, congenital defects, anemia, or chronic lung disease (ex. […]
Definition The purpose of intraoperative evoked potentials is to monitor neural pathways in hopes of avoiding iatrogenic injury to the nervous system. Sensory evoked potentials (SEPs) evaluate the integrity of ascending sensory tracts while motor evoked potentials (MEPs) deal with the functionality of descending motor pathways. SENSORY EVOKED POTENTIALS Three SEP modalities are used clinically: […]
Definition Nonbarbiturate hypnotic, no analgesic activity, used for induction & sup of anesthesia. Decreases cerebral metabolism, cerebral blood flow, and intracranial pressure. (superior to propofol in maintaining cerebral perfusion pressure) Effects on EEG: initial increase α amplitude followed by progressive decrease in activity Periods of burst suppression occur at higher doses. Use with caution in […]
Definition Hypomagnesemia Hypokalemia Respiratory alkalosis Subspecialty General Related Media Keyword history 63%/2011 67%/2014 See Also: Sources PubMed
Definition Drugs that decrease Lower Esophageal Sphincter (LES) tone Nitroglycerins (Isosorbide dinitrate, glycerylnitrate, itramintosylate, trolnitrate) Nitroprusside Anticholinergics (not when given with anticholinesterases) Beta-adrenergic agonists Aminophyllines (Theophyline, caffeine,cholintheophyline, glyphylin, oxitriphyline) Benzodiazepines (diazepam, flunitraqepam, nitrazepam, oxazepam, triazolam) Inhalational agents Tricyclic antidepressants Morphine (not when given with propofol) Meperdine ?nitrous oxide Propofol (high doses only) Dexmedetomindine (high doses […]
Definition Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. They may also have obstructive sleep apnea and lax cervical ligaments as well as other cervical abnormalities (ex. odontoid) leading to cervical instability (atlantooccipital instability in 9%). Children and adults may need down-sized endotracheal tubes. […]
Definition Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. They may also have obstructive sleep apnea and lax cervical ligaments as well as other cervical abnormalities (ex. odontoid) leading to cervical instability (atlantooccipital instability in 9%). Children and adults may need down-sized endotracheal tubes. […]
Definition Acute epiglottitis (supraglottitis) in the pediatric population is a potentially life threatening bacterial infection involving the supraglottic structures (lingular surface epiglottis, arytenoids, aryepiglottic folds). This infection is generally caused by Haemophilus influenzae type B (Hib) or Group A beta-hemolytic streptococci. Due to the advent of the Hib vaccine in the 1980’s, the presentation of […]
Definition Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. They may also have obstructive sleep apnea and lax cervical ligaments as well as other cervical abnormalities (ex. odontoid) leading to cervical instability (atlantooccipital instability in 9%). Children and adults may need down-sized endotracheal tubes. […]
Definition Some argue against doing a “test dose” because it lacks specificity and sensitivity for picking up an IT/IV epidural catheter placement. ideal test: safe for mom and fetus test dose is important if large volumes of concentrated local anesthetics are given traditional test dose: lidocaine: 1.5% w/ epinephrine bupivacaine 0.25% w/ epi 2-chloroprocaine w/ […]
Definition Postoperative ileus is almost universal following major abdominal surgery. Nearly 100 years ago, Cannon and Murphy demonstrated that opening the peritoneal cavity and manipulating the intestines resulted in significant inhibition of GI tract contractile function in dogs. It has been suggested that epidural analgesia can shorten the duration of postoperative ileus and thereby decrease […]
Definition Clonidine functions as a sympatholytic by stimulating presynaptic α2-receptors leading to decreased release of norepinephrine at both central and peripheral adrenergic terminals. In addition to its influence on the autonomic nervous system, it is well established that clonidine is an effective analgesic, and this is also attributable to its α2-agonist activity. Remember that a […]
Definition Dyspnea may occur due to proprioceptive blockade of afferent fibers from abdominal and chest wall muscles. Need to assess adequacy of ventilation then reassure the patient. Apnea may occur due to reduced medullary blood flow accompanying severe hypotension or from direct C3-C5 blockade, inhibiting phrenic nerve output. Immediate ventilator support required. Similar respiratory effects […]
Definition North American guidelines have recommended early enteral nutrition WITHOUT parenteral nutrition for caloric deficiency in the first seven days of critical illness. However, European guidelines have recommend parenteral nutrition as soon as possible to reach caloric & nutritional goals early after admission to the intensive care unit. There has been no high level evidence […]
Definition Indications Endobronchial intubation to achieve one lung ventillation has absolute and relative indications. Absolute Lung isolation to prevent spillage of pus or blood from an infected or bleeding source is an absolute indication for OLV. Massive atelectasis, sepsis, and pneumonia can result from contralateral contamination, which may be life-threatening. Bronchopleural or bronchocutaneous fistulae are […]
Definition EMLA (Eutectic Mixture of Local Anesthetics) is a eutectic mixture of lidocaine 2.5% and prilocaine 2.5% formulated as an oil in water emulsion developed to anesthetise intact skin. This eutectic mixture has a melting point below room temperature and therefore both local anesthetics exist as a liquid oil rather than as crystals. EMLA Cream […]
Definition Factor treatment: 1. Prothrombin complex concentrate Prothrombin Complex Concentrate (PCC) (trade name Octaplex or Ocplex[1]) is a combination of blood clotting factors II, VII, IX and X, as well as protein C and S.[1] It reverses the effect of warfarin (a coumarin anti-coagulant) and is used in cases of significant bleeding in patients with […]
Definition Intracranial pressure (ICP) is determined by the volume of brain parenchyma (80%), blood (12%), and CSF (8%) within a rigid cranial vault. Normal ICP ranges from 5-15mmHg. Because the cranial compartment is enclosed by a rigid skull, it has a limited ability to accommodate additional volume. When intracranial contents increase in volume (e.g., secondary […]
Definition FRC = residual volume + expiratory reserve volume = volume of gas in the lungs after normal expiration = lung volume where elastic recoil of chest and lung are in equilibrium (but in opposite directions) Increased FRC (in general) results from: Decreased inward lung recoil Increased outward chest recoil Bronchoconstriction/airway obstruction Lung hyperinflation Differential […]
Definition Sodium levels are affected by ADH (hypothalamus), aldosterone (renin-angiotensin-aldosterone axis), glucocorticoids and mineralocorticoids (pituitary axis). Potassium is affected by aldosterone, steroids, and insulin. Calcium levels are increased as PTH is released. Electrolytes and Related Hormones Sodium: ADH (retains fluid), glucocorticoids (cortisol) and mineralocorticoids (aldosterone) both retain Na Potassium: aldosterone (excretes K), gluco- and mineralocorticoids […]
Definition Vasopressin, also known as antidiuretic hormone (ADH), is a peptide hormone made in the hypothalamus and has both an immediate and long term effect on hemodynamics. The immediate effect is as a direct peripheral vasoconstrictor. A slower acting mechanism is the process of increasing collecting duct permeability and retaining water. Possibly increasing intravascular volume, […]
Definition Opioids produce a dose related decrease in the frequency and amplitude of the EEG. Low dose opioids show a loss of beta waves and a slowing of alpha waves. Moderate dose opioids show diffuse theta waves and some delta waves. High dose opioids show delta waves (high amplitude, 0-4 Hz). See Delta Waves on […]
Definition The stimulus leads to increases in cerebral blood flow and increased ICP. Initially, the seizure activity causes a large parasympathetic discharge with bradycardia, atrial or ventricular premature beats, and occasional asystole. This is followed by sympathetic discharge causing tachycardia (maximal at two minutes), hypertension, ST-segment depression and T-wave inversion not associated with myocardial enzyme […]
Definition ECT requires both general anesthesia and paralysis. Pretreatment with glycopyrrolate may reduce the incidence of bradycardia and decrease oral secretions following the initial parasympathetic response. Induction is intravenous, followed by complete paralysis and placement of a bite block. According to Miller, “Methohexital (0.75 to 1.0 mg/kg) is the most commonly used drug for ECT […]
Definition Before discussing contraindications, it is important to first understand the physiologic effects of ECT. These include : Large increases in cerebral blood flow and intracranial pressure Initial parasympathetic discharge manifested by bradycardia, occasional asystole, premature atrial and ventricular contraction, hypotension and salivation Following parasympathetic reaction is a sympathetic discharge associated with tachycardia, hypertension, premature ventricular […]
Definition External cardiac pacemaker function should not be affected by ECT because the current path is far from the heart. Patients with a history of CAD, CHF, and valvular heart disease may benefit from invasive monitoring to assess myocardial function and permit aggressive hemodynamic control. Routine blunting of sympathetic nervous system responses by B-blockers is […]
Definition If a lead becomes loose, you can get baseline wander TO REDUCE BASELINE WANDER: A) Use muscle relaxation B) Arrange patient cable so there is no pull on the lead wires to prevent electrodes from moving C) Check for secure application of electrodes. Loose electrodes may accentuate wandering caused by movement of the limbs […]
Definition Definition: full-thickness separation of the uterine wall and the overlying serosa Incidence of ~ 1% during VBAC, with a maternal/fetal morbidity rate of 10% or higher. Induction of labor increaes the risk 10-fold. ACOG therefore recommends that an anesthesiologist be immediately available for any VBAC. Fetal bradycardia is the most sensitive sign. Other signs […]
Definition In an adult the dural sac terminates caudally at S2. The termination of the adult spinal cord, on the other hand, is at L1-2 and is called the conus medullaris. In newborns the dura mater ends at S3, and the conus medullaris at L3. This changes over the first year of life. Spinal Anatomy […]
Definition The dura mater is the outermost of the spinal meninges. It is a thick, fibroelastic membrane composed of collagen and elastin fibers that is a continuation of the cranial dura. At its cephalad origin, it fuses with the periosteum of the skull at the foramen magnum, and it continues caudally in a circumferential manner […]
Definition Phosphorus Hypophosphatemia (defined as phosphate <2.5mg/dL) is reported in 17-28% of critically ill patients. It can result from increased renal excretion of phosphate, decreased absorption by the GI tract, or most commonly, an increase in intracellular movement of phosphate. Phosphate < 1.0 mg/dL may also lead to hemolytic anemia, heart failure, tachypnea, CNS symptoms (including seizures), and […]
Definition Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. They may also have obstructive sleep apnea and lax cervical ligaments as well as other cervical abnormalities (ex. odontoid) leading to cervical instability (atlantooccipital instability in 9%). Children and adults may need down-sized endotracheal tubes. […]
Definition Patients with Down’s syndrome may have an airway complicated by both macroglossia, tonsillar/adenoidal hypertrophy, micrognathia, and a short neck. They may also have obstructive sleep apnea and lax cervical ligaments as well as other cervical abnormalities (ex. odontoid) leading to cervical instability (atlantooccipital instability in 9%). Children and adults may need down-sized endotracheal tubes. […]
Definition Most common is the Robertshaw tube, available as both a L and R-sided tube. Sizes include a 28F (pediatric) as well as 35F, 37F, 39F, and 41F. All are PVC with D-shaped lumens, disposable. Blue represents the endobronchial lumen/cuff. Note that R-sided tubes have a donut-shaped endobronchial cuff, which allows separate access to the […]
Definition The liver is responsible for synthesis of clotting factors and other important proteins involved with regulating the coagulation cascade. Therefore, even in patients with a normal preoperative coagulation profile, alterations in bleeding and thrombosis have been observed following donor hepatectomy. This becomes important when considering perioperative pain management in these patients in regards to […]
Definition Anesthesiologists in particular need to be aware that studies indicate that many patients with DNR orders in their charts (up to 46%) may be unaware that the order exists, even when they are competent. Documentation of discussion of DNR orders with the patient or appropriate surrogates must take place; anesthesiologists and surgeons should nevertheless […]
Definition GA for C-section is most often done in an emergency situation (fetal distress, failed regional technique, high spinal, aspiration, cardiac arrest) and is associated with a higher mortality rate than regional techniques. mortality during GA is most often from hypoxemia, i.e. failed intubation, failure to recognize esophageal intubation, or failure to ventilate […]
Definition Difficult airway algorithm Subspecialty General Related Media Keyword history 93%/2008 95%/2011 See Also: Sources PubMed Jeffrey L Apfelbaum, Carin A Hagberg, Robert A Caplan, Casey D Blitt, Richard T Connis, David G Nickinovich, Carin A Hagberg, Robert A Caplan, Jonathan L Benumof, Frederic A Berry, Casey D Blitt, Robert H Bode, Frederick W […]
Definition A differential block refers to the clinical phenomenon that nerve fibers with different functions have different sensitivities to local anesthetic blockade. This is well proven in both neuraxial and peripheral nerve blocks. Classically, it was taught that small diameter axons (ex. C-fibers) are more susceptible than larger diameters, but this is not true – […]
Definition Croup, also known as laryngotracheobronchitis, is primarily subglottic. Viral etiology. History: Age typically 3 months to 3 years Physical exam: Inspiratory stridor, barking cough, and hoarseness. Airway obstruction is rare with croup. Diagnostic imaging: X-ray – “steeple sign” or narrowing of subglottic region. Subspecialty General Related Media Keyword history 99%/2008 See Also: Sources PubMed
Definition I. What is DI? A. Central DI – decreased secretion of antidiuretic hormone (ADH, aka AVP) – results in polyuria and polydipsia by diminishing the patient’s ability to concentrate urine – defect in one or more sites involving the hypothalamic osmoreceptors, supraoptic or paraventricular nuclei, or the supraopticohypophyseal trac B. Nephrogenic DI – decrease […]
Definition Clinical Signs of Diabetic Autonomic Neuropathy: Hypertension Painless myocardial ischemia Orthostatic hypotension Lack of heart rate variability (normal HR variability during voluntary deep breathing of 6 breaths/min is >10 beats/min) Reduced heart rate response to atropine and propranolol Resting tachycardia Early satiety Neurogenic bladder Lack of sweating Impotence Diabetic patients with hypertension have a […]
Definition von Willebrand’s disease is a hereditary deficiency of von Willebrand’s factor (VWF), causing platelet dysfunction. Bleeding tendency is usually mild. Screening tests show a normal platelet count and, possibly, a slightly prolonged PTT. Diagnosis is based on low levels of VWF antigen and abnormal ristocetin cofactor activity. Treatment involves control of bleeding with replacement […]
Definition Donor heart, which is completely denervated, does not respond to manipulations of the parasympathetic nervous system (including reductions in parasympathetic outflow, ex. anticholinergics, anticholinesterases, or increases on PNS outflow, ex. phenylephrine), or neuronal SNS outflow (ex. cardioaccelerator fibers, although systemic epinephrine may still affect the heart). Furthermore, denervation impairs the response to changes in […]
Respiratory muscle weakness is common among patients who have neuromuscular disease. It can be acute (e.g., guillain-barré syndrome), chronic and relapsing (e.g., multiple sclerosis, myasthenia gravis), or relentlessly progressive (e.g., amyotrophic lateral sclerosis [als]). It is estimated that 15-28% of patients with myasthenia gravis and 20-30% of patients with Guillain-Barré syndrome will require invasive mechanical […]
Definition Differential diagnosis of delayed emergence can be classified into one of three causes: drug effects, metabolic disorders, or neurologic disorders. If a patient doesn’t “wake” after an anesthetic you have to go down these three in that particular order. Delayed Emergence Rapid Panel Vital signs (including temperature) Twitch monitor Neurologic Exam (pupils, cranial nerves, […]
Definition The variance is the average difference of each value in the sample from the mean. As, by definition, the sum of the difference of each value from the mean would equal 0, the difference of each value from the mean is squared. The standard deviation is simply the square root of the variance. It […]
Definition In medical terms, sensitivity is the percentage of people who test positive for a disease that have that disease. A highly sensitive test will essentially rule out those who do not have disease. Highly sensitive tests are often used as “screening tests.” Specificity is the percentage of people without the disease who test negative […]
Definition Detection of a paced (VP) or sensed ventricular (VS) resets its clock an also initiates the ventricular refractory period (VRP) to prevent T-wave oversensing and initiates the post-ventricular atrial refractory period (PVARP) which helps prevent oversensing of retrograde P waves. VA interval (time from VP/VS to atrial firing) plus AVI (atrioventricular interval, roughly ~ […]
Definition Cylinders stored on the back of anesthesia machines are E cylinders. The height of an E cylinder is 24.9 inches, the diameter of the base is 4.38 inches, and the empty weight is 5.90 kg. Both air and oxygen are stored as compressed gasses, and therefore the volume can be calculated if the pressure […]
Definition Cyanide toxicity causes uncoupling of oxidative phosphorylation, interrupting aerobic metabolism and forcing a shift to anaerobic metabolism, leading to decreased O2 consumption, elevated lactate and severe metabolic acidosis. Cyanide enters the body as gaseous HCN, water-soluble K-CN and Na-CN, and poorly soluble salts with Hg, Cu, Au, and Ag. Cyanogens, such as cyanogen-Br or […]
Definition CVP is generally measured at the junction of the superior vena cava and the right atrium. This is most commonly this is done via a central venous catheter placed through the right internal jugular vein. A normal CVP waveform contains five components. These components include three peaks (a, c, v) and two descents (x, […]
Definition Mixed venous saturation can help assess tissue oxygen delivery. By using the derivation of the Fick equation, the mixed venous saturation can be determined by: SvO2 = SaO2 – [(VO2) / (Hb x 1.36 x Q)] SvO2: mixed venous saturation SaO2: arterial oxygen saturation VO2: oxygen consumption Hg: hemoglobin Q: cardiac output From […]
Definition A pressure-volume (PV) loop for the left ventricle is generated as left ventricular pressure is plotted against left ventricular volume at multiple time points during a complete cardiac cycle. The cycle can be divided into several basic phases: ventricular filling (diastole), isovolumetric contraction, ejection phase (the top of the curve), and isovolumetric relaxation. The […]
Definition Administration of large volumes of fluid deficient in platelets and clotting factors will predictably lead to the development of a coagulopathy as a consequence of dilution. There has been much research into whether patients first become deficient in platelets of clotting factors during massive volume resuscitation. In the end, this question is not likely […]
Definition One unit of Cryoprecipitate contains approximately 250 mg of Fibrinogen. Also, it is a VERY concentrated source of Factor 8 How is it prepared? by slowly thawing a unit of FFP at temperatures just above freezing (1-6 °C), typically in a water bath or a refrigerator. The product is then centrifuged to remove the […]
Complex regional pain syndrome (CRPS), is a regional, posttraumatic, neuropathic pain problem that most often affects one or more limbs. Like most medical conditions, early diagnosis and treatment increase the likelihood of a successful outcome. Accordingly, patients with clinical signs and symptoms of CRPS after an injury should be referred immediately to a physician with […]
Definition Positioning injuries associated with craniotomy are best considered by the position the patient will be in for the surgery. The risks of injury associated with each of the following patient positions are not necessarily exclusive to neurosurgical procedures. Sitting Position The sitting position for cranial surgery is associated with a high incidence of air […]
Definition Anitfibrinolytics are frequently used in patients placed on CPB. The two available lysine analogs, ε-aminocaproic acid and tranexamic acid, bind to lysine binding sites on plasminogen and fibrinogen and thereby inhibit plasminogen activator and plasmin release. When administered before CPB, these agents clearly inhibit fibrinolysis, decrease mediastinal bleeding, and depending on the study, may […]
Definition Coronary perfusion pressure is defined as the difference between systemic arterial pressure and intraventricular pressure. Because LV pressures equal or exceed systemic arterial pressures (as the LV is the source of systemic pressure some pressure drop occurs through the LVOT and aortic valve), left ventricular coronary perfusion is intermittent and only occurs during diastole. […]
Definition Left ventricular coronary perfusion pressure is the pressure gradient that drives LV coronary perfusion (supplied primarily by the LAD and circumflex territories). It is defined as the aortic diastolic pressure (DP) minus the left ventricular end-diastolic pressure (LVEDP). This can be abbreviated by: CorPP = DP – LVEDP Subspecialty Cardiac Anesthesia Related Media Keyword […]
Definition Anatomy of Coronary Artery System According to Barash chapter 10 “The left main and right coronary arteries arise from the aorta behind the left and right aortic valve leaflets. The coronary ostia remain patent throughout systole because eddy currents prevent the valve leaflets from contacting the aortic walls. The left main coronary artery divides […]
Definition Prevention is key to function preservation, should focus on limiting risk factors which include : Creatinine greater than 1.5 mg/dL GFR < 60 ml/min Diabetic nephropathy Hypovolemia High doses of contrast media Multiple myeloma Treatments that appear to be effective contrast nephropathy include : Periprocedural continuous hemofiltration Oral N-acetylcysteine Bicarconate infusion Subspecialty […]
Definition The context-sensitive half-time is the time required for blood or plasma concentrations of a drug to decrease by 50% after discontinuation of drug administration. The context-sensitive half-time often cannot be predicted by the elimination half-life (a measure of the time needed for actual drug metabolism or elimination) because it also depends on drug distribution. […]
Definition Stoelting’s Anesthesia and Co-existing Disease 5/e says: “A prominent y-descent of the jugular venous pressure (Friedreich’s sign) reflects the predominance of right ventricular filling in early diastole that is seen with constrictive pericarditis.” The pressure tracing during diastole of the RV, LV, and RA will equalize. See Figure 7-3 B for the CVP tracing […]
Definition Background Congenital Long QT Syndrome (LQTS) may occur with (Jervell and Lange-Nielsen syndrome) or without (Romano-Ward syndrome) deafness. Presents as lightheadedness, syncope, torsades, and cardiac arrest. May be triggered by adrenergic stimulation or even auditory stimulation (LQT1 and 2). Three ion channel abnormalities have been identified – LQT1 and LQT2 (K+), and LQT3 (Na+). […]
Definition Pulmonary hypertension (PHT) in Congenital Heart Disease (CHD) is a common problem. It can occur secondaary to volume or pressure overload secondary to CHD or can develop after vascular injury related with cardiopulmonary bypass and lung injury. Depending on the severity of pulmonary hypertension, patients may develop right ventricle overload, ischemia and dysfunction. Perioperative […]
Definition A decrease in prostaglandin E2 (PGE2), along with exposure to oxygenated blood, causes the ductus arteriosus to close after birth. PGE1 (0.1 ug/kg/min) maintains ductus patency (and in some cases can reopen a closed duct), by directly acting on vascular smooth muscle. PGE1 is essential in patients with HLHS, AS, interrupted arch, in which […]
Definition Congenital lobar emphysema is a disorder of lung parenchyma that results in hyperinflation of the lung and respiratory distress in infants from newborn to six months of age. It is a rare event with an incidence of 1 in 20,000-30,000. The left lung is more commonly involved and specifically the left upper lobe is […]
Definition These can include: A complication seen with early versions of the Univent occurred when a fracture of the blocker cap connector was found. Failure to achieve lung separation because of abnormal anatomy or lack of a seal within the bronchus also has been reported. Inclusion of the bronchial blocker or the distal wire loop […]
Definition Also known as third-degree AV block, complete heart block is a condition where there is dissociation between the electrical activity of the atria and ventricles. As a result, the two chambers contract independently with the ventricle in its own rhythm. The ventricular escape rhythm is typically bradycardic, with heart rates usually less than 40 […]
Definition Compartment syndrome occurs when volume (usually edema and/or blood) accumulates in a confined osseofascial space to the extent that delivery of oxygen to tissues is compromised. It is most common with orthopedic trauma (40% tibial shaft, 18% forearm, also femur and ankle) although 23% are caused by soft tissue trauma with no fracture. Compartment […]
Definition Considerations in the perioperative period: FFP 10-20 ml/Kg should correct PT to near normal for 12-24h Cryoprecipitate also used: higher conc of FVIII and fibrinogen Platelet transfusion indicated if <60.000 Vitamin K 10mg SC x3d, only effective if cholestatic disease RBC transfusion can precipitate encephalopathy due to nitrogen load rFVII only for bleeding not […]
Definition Issue: Desiccated (or dry) CO2 absorbers such as soda lime and Baralyme can degrade inhaled anesthetics to carbon monoxide, and my produce carboxyhemoglobin concentrations in excess of 30%. Mechanism: These CO2 absorbers contain strong bases (sodium hydroxide and potassium hydroxide) that can extract labile protons from anesthetic molecules, resulting in the production of CO. […]
Definition Issue: Desiccated (or dry) CO2 absorbers such as soda lime and Baralyme can degrade inhaled anesthetics to carbon monoxide, and my produce carboxyhemoglobin concentrations in excess of 30%. Mechanism: These CO2 absorbers contain strong bases (sodium hydroxide and potassium hydroxide) that can extract labile protons from anesthetic molecules, resulting in the production of CO. […]
Definition Issue: Desiccated (or dry) CO2 absorbers such as soda lime and Baralyme can degrade inhaled anesthetics to carbon monoxide, and my produce carboxyhemoglobin concentrations in excess of 30%. Mechanism: These CO2 absorbers contain strong bases (sodium hydroxide and potassium hydroxide) that can extract labile protons from anesthetic molecules, resulting in the production of CO. […]
Definition Issue: Desiccated (or dry) CO2 absorbers such as soda lime and Baralyme can degrade inhaled anesthetics to carbon monoxide, and my produce carboxyhemoglobin concentrations in excess of 30%. Mechanism: These CO2 absorbers contain strong bases (sodium hydroxide and potassium hydroxide) that can extract labile protons from anesthetic molecules, resulting in the production of CO. […]
Definition Carbon dioxide is transported in blood in three forms: dissolved in plasma, as bicarbonate, and coupled to proteins in the form of carbamino compounds. Bicarbonate represents the largest fraction of the CO2 in blood (~88%). On the venous side of systemic capillaries CO2 enters red blood cells (RBC) where it combines with water to […]
Definition The chemical control of breathing is based on a negative feedback loop and chemoreflex. Thus, when the central and peripheral chemoreceptors sense an increase in [H+], breathing is stimulated by a chemoreflex that includes the central nervous system, respiratory muscles, and changes in alveolar ventilation, resulting in correction of the [H+], hence the negative […]
Definition ASA closed malpractice claims data to identify areas of morbidity, mortality and prevention thereof started in 1985. It is overseen by the Committee on Professional Liability of the ASA. The database includes 8954 cases. 42% of claims in the 1980s involved death and permanent brain injury, this dropped to 32% of claims in the […]
The power of a statistical test is the probability that the test will reject a false null hypothesis (that it will not make a Type II error). As power increases, the chances of a Type II error decrease. The probability of a Type II error is referred to as the false negative rate (β). Therefore […]
Definition During hypothermia, pH-stat (reporting of blood gases at body temperature) corrects for the effects of temperature on pH in order to keep the pH static (7.4). This often results in the addition of CO2 to the CPB circuit. In contrast, alpha-stat (reporting of blood gases at 37 degrees) attempts to preserve electrical neutrality especially […]
Definition Morphine and methadone are both opioids used in pediatric pain management. Morphine is more protein bound in adulthood than during the neonatal period (30% vs 20%). Morphine is metabolized to morphine 3-glucoronide and morphine 6-glucoronide. This occurs through sulfation and gluronidation. The enzymes guiding gluronidation are relatively immature in the neonate so preferentially more […]
Unlike benign pain, usage of opioids in chronic pain management elicits little controversy. Nevertheless, there is significant disagreement in drug choice, timing, and dosage leading to significant practice variance. In one large series, 95% of patients with advanced cancer have pain, only 50% report that it is well treated and 25% were rated as having […]
Methadone is roughly equianalgesic with morphine, but has a long and variable half-time (13-100 hours). It is an NMDA antagonist in addition to an opioid agonist. It appears to reduce post-operative opioid consumption in patients on chronic opioid therapy. A recent Cochrane Database Systematic Review supports the assertion that methadone offers equal analgesic potency with […]
Definition Local anesthetics are weakly basic drugs that are principally bound to 1-acid glycoprotein. Placental transfer depends on three factors: (1) pKa, (2) maternal and fetal pH, and (3) degree of protein binding. Except for chloroprocaine, fetal acidosis produces higher fetal-to-maternal drug ratios because binding of hydrogen ions to the nonionized form causes trapping of […]
Definition What type of Local? Ester Mechanism of Action Blocks the generation and the conduction of nerve impulses, presumably by increasing the threshold for electrical excitation in the nerve, by slowing the propagation of the nerve impulse and by reducing the rate of rise of the action potential. Metabolism Plasma cholinesterases (just like succinylcholine), also […]
Definition The Child-Pugh score was the first attempt to provide an objective measure of preoperative morbidity and mortality in patients with chronic liver disease. The score measures five favors with each factor scored from 1 – 3. Factor 1 point 2 points 3 points Bilirubin (mg/dl) < 2 2 – 3 < 3 Albumin (g/dl) […]
This is a test used to evaluate an hypothesis by comparing measured results to theoretically expected results (i.e. the Null hypothesis). This test is designed to convert the differences between “expected” and “measured” results into the probability of their occurring by chance. After using the conversion calculations, it basically compares a calculated value X2 with […]
Chi-square test for categorical variables determines whether there is a difference in the population proportions between two or more groups. In the medical literature, the Chi-square is used most commonly to compare the incidence (or proportion) of a characteristic in one group to the incidence (or proportion) of a characteristic in other group(s). For example, […]
Definition The Frank-Starling Curve The most common type of heart failure is systolic dysfunction. With systolic dysfunction, the Frank-Starling curves shifts down and to the right because of the loss of contractility. Stroke volume can be increased by increasing inotropy, decreasing the afterload, or increasing the preload. Increasing preload will not necessarily increase stroke volume […]
Definition The intrinsic property of myocardium to increase the force of contraction in relationship to the stretch of cardiac muscle is the Frank-Starling relationship. This relationship is commonly used to describe the influence of ventricular end-diastolic volume (LVEDV or preload) on stroke volume (SV) and is illustrated to the left. Increasing preload will increase the […]
Definition Video depiction of the effect of CHF on the Frank-Starling curve. Accessed 2/28/15. Subspecialty Cardiac Anesthesia Related Media Keyword history 73%/2015 71%/2012 Similar Keyword: Frank-Starling law: Ventric failure Sources PubMed
Definition Chest wall compliance is the opposite of elasticity, and elasticity is the tendency of lung tissue to return to its original (or relaxed) position after an applied force has been removed. Compliance is essentially the ability of the lung tissue to “absorb” the same applied force, which generally results from a change in intrathoracic […]
Cervical Precaution According to Barash, chapter 36, “Maintenance of immobilization of the injured spine is of paramount importance. If a cervical spine fracture is suspected, immobilization or manual inline stabilization of the neck is necessary before the patient is moved. If the patient has a thoracic or lumbar injury, a careful log-rolling maneuver should be […]
Definition Cerclage, or surgical reinforcement of the cervix, is primarily used to prevent preterm birth in patients with cervical insufficiency. Cerclage is most often performed transvaginally, either the McDonald or the more invasive Shirdokar (Antiseptic 1955;52:299), though transabdomianl cerclage can be performed if there is insufficient cervical tissue for transvaginal cerclage or if prior transvaginal […]
Definition Generally treated with nimodipine (controversial, probably works not by dilating vessels but as a neuroprotectant, if at all) and triple-H therapy (hypertension, hypervolemia, and hemodilution, also controversial). Increased blood flow, as opposed to pressure, may be more important. In the aftermath of subarachnoid hemorrhage, when nimodipine & HHH fail to avert cerebral vasospasm, balloon […]
Definition Used in cardiac surgery, thoracic surgery, neurosurgery. Temperature reduced to 15-22 degrees C, after which circulation is stopped. Note that because you cannot actually measure brain temperature, full flow CPB is maintained 20-30 minutes after reaching 15-22C, to ensure adequate cerebral cooling. If BIS or EEG is available, verify isoelectricity before cessation of circulation. […]
Definition Increased neuronal activity results in increased local brain metabolism which in turn is associated with a proportional increase in cerebral blood flow (CBF). This mechanism, referred to as flow-metabolism coupling, is regulated by metabolic, glial, neural, and vascular factors. Hypothermia decreases cerebral metabolic rate (CMR) by 6% to 7% per degree Celsius, with a […]
Definition Central sleep apnea (CSA) DEFINITION: is when you repeatedly stop breathing during sleep because the brain temporarily stops sending signals to the muscles that control breathing. (vs OSA which is due to upper airway obstruction) SIGNS & SYMPTOMS: chronic fatigue, daytime sleepiness, morning headaches, restless sleep but not associated with snoring. ASSOCIATIONS: Any disease […]
Definition Infection is the most common late complication of central venous cannulation, occuring in 5% of patients with central venous catheters (150,000 to 250,000 cases of catheter-related blood stream infection [CRBSI] per year). The overall mortality of patients with nosocomial bloodstream infections (not restricted to CRBSI) is ~ 35%, and the cost of one CRBSI […]
Definition Introduction The celiac plexus is the largest plexus of the sympathetic nervous system. It contains preganglionic sympathetic fibers from greater and lesser splanchnic nerves (emerge from the thoracic sympathetic ganglia, T5 to T12) as well as postganglionic sympathetic and preganglionic parasympathetic fibers. It provides sensory innervation and sympathetic outflow to stomach, liver, spleen, pancreas, […]
Definition Indications To relieve the sympathetic response and associated stress/endocrine response to abdominal surgery. Often times used in conjunction with an intercostal nerve block. Subspecialty Pain and Regional Anesthesia Related Media Keyword history 83%/2008 See Also: Sources Wedel DJ, Horlocker TT. Nerve Blocks. Chapter 52. In: Miller’s Anesthesia. 7th Edition. Saunders; 2009. PubMed
Definition The Celiac Plexus is made up of 1-5 ganglia carrying afferent fibers from the upper abdominal organs (stomach to mid transverse colon, including pancrease and gallbladder) as well as sympathetic preganglionic fibers from greater (T5-T10), lesser (T10-T11), and least (T12) splanchnic nerves. The plexus is located in the upper abdomen typically at the level […]
Definition ACE inhibitors and ARBs are two medications that are commonly used in the post-MI patient. These medicines work by inhibiting the renin-angiotensin aldosterone system at two different points. The ACE inhibitors prevent the conversion of angiotensin 1 to angiotensin 2. The ARBs block the angiotensin 2 receptor and prevent further activation of the RAAS […]
Definition Absolute Contraindications Angioneurotic edema: even if not due to ACE Inhibitor Pregnancy (serious Teratogenicity – black box warning) Renal Artery Stenosis ACE Inhibitor related Allergic Reaction Relative Contraindications Aortic Stenosis Hypertrophic Cardiomyopathy Subspecialty General Keyword history 91%/2012
Definition Introduction The celiac plexus is the largest plexus of the sympathetic nervous system. It contains preganglionic sympathetic fibers from greater and lesser splanchnic nerves (emerge from the thoracic sympathetic ganglia, T5 to T12) as well as postganglionic sympathetic and preganglionic parasympathetic fibers. It provides sensory innervation and sympathetic outflow to stomach, liver, spleen, pancreas, […]
Definition A congenital diaphragmatic hernia (CDH) is an early developmental defect that results in the extrusion of intraabdominal organs (ie. stomach, small intestines, kidney, liver) into the thoracic cavity. This defect can be isolated or associated with multiple congenital abnormalities with cardiac anomalies being the most common. Ninety-percent of CDH are located in the posterolateral […]
Definition Treatment Based on the symptomatology. Treat seizures with GABA agonists. Treat convulsions with paralytics and airway management. Vasopressors may be indicated, although in some animal models they have been shown to promote CNS toxicity (still, on that basis they should not be withheld in the setting of cardiovascular collapse). Total cardiovascular collapse may be […]
Definition Cerebral blood flow and cerebral metabolic rate (normally 3.0-3.8 ml O2/ 100gm brain/min) are coupled in the absence of pathology and or various anesthetic drugs. This means when cerebral metabolic rate increases or decreases so does cerebral blood flow. However, some anesthetic drugs are known to alter CBF and CMRO2. Various drug classes and […]
Definition Upregulation of Acetylcholine receptors leads to increased sensitivity to Succinylcholine and risk for hyperkalemia due to depolarization of the muscle membrane. May occur in: 1) Spinal Cord Injury 2) Stroke 3) Burns • After immobilization, upregulation of NAChRs • Avoid Succinylcholine – especially after 24 hours post burn and for up to 1-2 years […]
Definition Very safe, can be used to provide peri- and postoperative analgesia, can be sole anesthetic or can be combined with general anesthesia. Indications a. Anesthesia and analgesia below the umbilicus – the very young a caudal block may be adequate to carry out urgent procedures such as reduction of incarcerated hernias -superficial operations such […]
Categorical data is also known as nominal data, meaning that one uses labels as opposed to numbers; for example, race and gender are categorical variables. The central tendency of categorical variables is given by its mode, since median and mean can only be computed on numerical data. Therefore, it does not follow a normal bell-curve […]
Definition Orthotopic heart transplantation results in total autonomic denervation of the heart. In this situation, carotid sinus stimulation will have minimal effects as the autonomic nervous system loop is not intact in order to effect heart rate change. Whether reinnervation occurs has been a matter of some debate. Some small longitudinal studies have indicated that […]
Definition Carotid sinus reflex can be used therapeutically to produce vagal stimulation that may be an effective treatment for supraventricular tachycardia. A typical response to acute hypertension is increased parasympathetic nervous system stimulation that decreases HR. Vagal stimulation and decreases in sympathetic nervous system activity also decrease myocardial contractility and cause reflex vasodilation. Subspecialty […]
Definition CEA requires temporary clamping of the carotid artery being worked on rendering the ipsilateral hemisphere dependent on collateral flow from the vertebral arteries and the contralateral carotid artery through the Circle of Willis. Neurologic monitoring is used to verify adequate perfusion of bilateral regions of the brain and to guide decision making in regards […]
The carotid bodies are chemosensitive cells at the bifurcation of the common carotid that respond to changes in oxygen tension and, to a lesser extent, pH. in contrast to central chemoreceptors, which primarily respond to PaCO2 and the aortic bodies [output via cn X], which have primarily circulatory effects (bradycardia, hypertension, adrenal stimulation, and also […]
Definition The pericardial sac typically has 15-30 ml fluid. Cardiac tamponade is caused by an increased amount of fluid in the pericardial sac, which compresses the heart. To a point, the body can adapt by increased adrenergic tone which in turn increases systemic venous pressure and heart rate. This increase in pressure prevents the heart […]
Definition Auscultatory Zones Aortic: RUSB (right upper sternal border) Pulmonic: LUSB (left upper sternal border) Tricuspid: 4LICS (4th left intercostal space), on the sternal border Mitral: 5 LICS (5th left intercostal space), several cm lateral to the 4LICS Apex Beat Located anywhere from the 4th to 5th intercostal space, 6-10 cm lateral to midline Borders […]
Definition Perioperative indications for pacemaker placement: any documented symptomatic bradyarrythmia a new bundle branch block a second degree type II aV block a third degree AV block associated with MI a bifascicular block in a comatose patient (controversial) refractory supraventricular tachyarrhythmias Indications 1-5 generally require ventricular pacing. Refractory supraventricular tachyarrhythmias will require atrial pacing electrodes […]
Definition For more information on cardiac risk in non-cardiac surgery, see Cardiac Risk (Anesthesia Text). For more information on cardiac risk in cardiac surgery, see Risk Stratification in Cardiac Surgery. Revised Cardiac Index Risk factors are: history of ischemia or heart disease, CHF, CVA, Cr > 2.0, IDDM, high risk surgery [Lee et al.] 0 […]
Diastole is divided into four phases and comprises 2/3 of the cardiac cycle. It begins when the aortic valve closes. This is the start of Isovolumic Relaxation (volume remains constant but the pressure in the ventricles fall). The next phase of diastole occurs when the mitral valve opens and allows for rapid ventricular filling. This […]
Definition In 2002, two large, prospective trials demonstrated that mild hypothermia after resuscitation from cardiac arrest and maintained for 12 to 24 hours improved survival and neurologic outcome in patients suffering from VF/VT arrest. Additional studies have suggested that therapeutic hypothermia may be beneficial following respiratory arrest, electrical mechanical dissociation, and asystole, provided that it […]
Definition Background Carcinoid tumors typically secrete excessive amounts of the hormone serotonin (although they may secrete many hormones). They arise from neuroendocrine cells throughout the body. Most commonly from organs derived from the primitive gut (90% come from distal ileum or appendix). Serotonin causes vasodilation, increased blood clotting (stimulation of platelet aggregation). It should be […]
Definition Carcinoid tumors release a variety of subtances (ex. serotonin, catecholamines, histamine) which can cause both hypertension and hypotension. Anesthetic management became significantly easier in the post-somatostatin era (ex. octreotide). Appropriate somatostatin analog therapy is the mainstay of initial perioperative management in these patients. Still, somatostatin analogs are not perfect, and avoidance of stimulation as […]
Definition Carbon monoxide (CO) binds to hemoglobin about 200x tighter than oxygen. This results in Functional anemia (hemoglobin is unavailable for oxygen transport) Decreased oxygen delivery at tissues (left-ward shift of the oxygen-hemoglobin disassociation curve) Carboxyhemoglobin Level Symptoms 1-3% Normal nonsmoker 4-9% Smokers 15-20% Mild signs of toxicity (headache, nausea and vomiting, dizziness, etc.) 20-40% […]
Definition Capnography directly reflects the elimination of CO2 by the lungs to the anesthesia device. It indirectly reflects the production of CO2 by tissues and the circulatory transport of CO2 to the lungs Capnography Waveform (image needed) Phase 0 – Inspiration Phase 1 – Represents the CO2-free gas from the airways (anatomical and apparatus dead […]
Definition Vascular Resistance PVR = 80(PAP – PCWP)/CO, normal 100-200 dyn-s/cm5 SVR = 80(MAP – CVP)/CO, normal 900-1200 dyn-s/cm5 Note that normal PA_systolic is 1/8th systemic SBP, and that pulmonary hypertension is defined as PA_systolic is > 1/4 systemic. Subspecialty Cardiac Anesthesia Related Media Keyword history 84%/2009 See Also: Sources PubMed
Definition In the United States, over one million Cesarean Section deliveries are performed annually. Cesarean delivery accounted for 32% of US births in 2009 while worldwide, the cesarean delivery rate accounts for only 15% of births. While the available evidence suggests there is no difference in maternal mortality when planned c-section is compared to planned […]
Definition Succinylcholine is composed of two molecules of acetylcholine. It binds to and stimulates cholinergic receptors at neuromuscular junction (1 mg/kg causes suppression of response to neuromuscular stimulation within 60 seconds). Butyrylcholinesterase, which is synthesized in liver and is not present at the NMJ, rapidly hydrolizes succinylcholine to succinylmonocholine and choline. Note that only 10% […]
Definition Pharmacologic neuroprotection/burst suppression has been of great interest for decades in the setting of acute cerebral insults. It has been studied in the setting of both global and focal cerebral injury. The interest stems from the knowledge that burst suppression with anesthetic agents (barbiturates, propofol, midazolam, isoflurane) results in a large reduction (approximately 50%) […]
Definition A core function of the upper airway is to protect the lungs from aspiration via various reflexes, one of which is bronchospasm, or the temporary narrowing of the bronchi via involuntary contraction of the local smooth muscle. However, not all episodes of bronchospasm protect the airways–ill-timed bronchospasm can prevent the physician’s ability to ventilate […]
Definition What are indications for Mechanical Ventilation? clinical or laboratory signs that the patient cannot maintain an airway or adequate oxygenation or ventilation. include respiratory rate > 30/min inability to maintain arterial O2 saturation > 90% with fractional inspired O2 (Fio2) > 0.60 PCO2 of > 50 mm Hg with pH < 7.25 A little […]
Definition Bronchospasm: Cause Bronchospasm is is a reversible reflex spasm of the smooth muscle in the bronchi. Bronchospasm is vagally mediated and caused by histamine, or one of many noxious stimuli, including cold air, inhaled irritants, and instrumentation (eg, tracheal intubation). Bronchospasm is mediated by vagal afferents which result in an increase in cyclic guanosine […]
Definition A bronchopleural fistula is a connection from the bronchial tree to the pleural space. Miller cites three ways this can occur: rupture of a bronchus, bulla, cyst, or abscess erosion due to carcinoma or inflammatory disease stump dehiscence status post pneumonectomy Ventilator management is difficult because positive pressure ventilation may lead to tension pneumothorax […]
Definition Bronchial blockers can be advantageous in patients in whom intubation with a double lumen tube is difficult or impossible (easier to place, can ventilate while placing). They allow for isolation of particular segments of the lung. They are technically simple. They can be used in pediatric patients. They work with existing single lumen tubes […]
Definition Operations on or near the brain stem in the posterior fossa can produce abrupt, profound, cardiovascular responses that may signal potential damage to the brainstem. Surgeries that stimulate the floor of the fourth ventricle (which affects the pons and medulla) or the cerebellopontine angle (ie acoustic neuromas or microvascular decompression of cranial nerve V) […]
Definition The three ketone bodies are acetone, acetoacetic acid, and beta-hydroxybutyric acid. Ketone bodies are derived from the incomplete oxidation of fatty acids in the liver and are used for energy (ATP generation) in the heart and brain. Ketone bodies are transported from the liver to other tissues, where acetoacetate and beta-hydroxybutyrate can be reconverted […]
Definition The pathophysiology of brain death is primarily related to the secondary effects of long-standing brain edema. The inciting event is an injurious event to the brain, such as a traumatic or cerebrovascular insult which will then lead to generalized hypoxia and resultant brain edema through either vasogenic (causing disruption of the BBB and increased […]
Definition Carotid sinus baroreceptors are located cephalad to the bifurcation of the common carotid artery. Manipulation of carotid sinus during carotid surgery activates the carotid sinus reflex by stimulating the carotid sinus baroreceptors, which give rise to impulse carried via glossopharyngeal nerve to the medulla oblongata. These afferent impulses lead to the activation the cardiac […]
Definition Brachial artery catheters appear to be significantly more reliable than radial artery catheters in the cardiac surgery population, especially post-CPB. That said, there is some concern about the safety of brachial artery catheters, primarily related to the lack of collateral circulation and proximity to the median nerve, which may be punctured in 1-2% of […]
Definition Botulinum A Toxin is produced by Clostridium botulinum which affects the presynaptic membrane of the neuromuscular junction where it prevents acetylcholine release and therefore muscle contraction. Inactivation persists until collaterals form in junction plates on new areas of muscle cell walls. An investigational use of Botulinum toxin is for pain management, the purported mechanism […]
Definition Blood oxygen transport DO2 = cardiac output x [O2] [O2] = 1.36 x Hgb x % Sat +0.003 x PaO2 Subspecialty General Related Media Keyword history 59%/2008 See Also: Sources PubMed
Definition According to Miller, “bilateral recurrent laryngeal nerve injury and resultant bilateral vocal cord paralysis can result in life-threatening upper airway obstruction. This situation must be anticipated in patients who have previously undergone contralateral carotid endarterectomy or neck surgery… Bilateral carotid endarterectomy is associated with loss of the normal ventilatory and arterial pressure responses to […]
Definition Thalassemia is a disorder of production of one of the proteins of hemoglobin. Hemoglobin is a protein in red blood cells and is responsible for the transport of oxygen to tissues. Hemoglobin is made up of two proteins, alpha globin and beta globin. Normal hemoglobin has two alpha and two beta globin protein chains. […]
Definition Benzodiazipines decrease the respiratory response to C02. This effect use usually insignificant when benzodiazepines are administered alone, but can be profound when they are co-administered with barbituates or narcotics. Always monitor ventilation in patients that have received benzodiazepines. Always have resuscitation equipment available when patients have received benzodiazepines. Subspecialty General Related Media Keyword history […]
Definition Pharmacologic neuroprotection/burst suppression has been of great interest for decades in the setting of acute cerebral insults. It has been studied in the setting of both global and focal cerebral injury. The interest stems from the knowledge that burst suppression with anesthetic agents (barbiturates, propofol, midazolam, isoflurane) results in a large reduction (approximately 50%) […]
Definition Axillary Nerve Block anatomy at the level of the axilla, the nerves are in their terminal branches the median, ulnar and radial nerves lie around the axillary artery and are blocked with a single injection. the musculocutaneous nerve however lies lateral to the axillary artery in the coracobrachialis muscle and requires a separate injection […]
Definition During the axillary approach to the brachial plexus, the block is performed in the axilla, where large terminal branches have formed. At this point, the musculocutaneous nerve lies deep within the coracobrachialis, having already left the proximity of the other nerves. A separate block is essential to complete forearm and wrist anesthesia. The musculocutaneous […]
Definition The axillary approach to the brachial plexus is associated with a very low complication rate, providing intravascular injection is avoided. Although controversial, repeated elicitation of paresthesia at multiple sites may increase the incidence of postoperative neuropathies. Hematoma and infection are very rare. Subspecialty Pain and Regional Anesthesia Related Media Keyword history 83%/2009 See Also: […]
Definition Acute blood loss leads to decreased cardiac output, tachycardia, hypotension, and hypovolemic shock. Inadequate organ perfusion and oxygen delivery interfere with aerobic metabolism. Increased anaerobic metabolism leads to production of lactic acid and metabolic acidosis. The body’s buffering capacity is reduced due to loss of bicarbonate and hemoglobin during hemorrhage. The kidneys can begin […]
Definition Loss of the atrial “kick” (contraction) or AV dyssynchrony can result in a significant increase in mean atrial pressure and pulmonary congestion. AV pacing in these patients, therefore, can augment ventricular filling and cardiac output through the Frank-Starling relationship, improves venous return, and assist AV valve closure. AV sequential pacing results 10±50% improvement in […]
Definition The autonomic nervous system is made up of 2 subdivisions: sympathetic and parasympathetic systems. The sympathetic system originates from the thoracolumbar regions (T1-L2) of the spinal cord. The parasympathetic system originates from craniosacral regions (brainstem nuclei CN III, VII, IX, and X as well as sacral levels S2-S4). In general, there are 2 neurons […]
Definition The sympathetic nervous system originates from T1-L2/3. Preganglionic SNS fibers to the upper extremity originate in the first four or five thoracic segments, and synapse in the superior, middle, and inferior (stellate) cervical ganglia. In 80% of people the stellate ganglia is actually made up of both the inferior cervical and first thoracic ganglia. […]
Definition Patients with a spinal cord injury at T7 or higher are at risk for autonomic hyperreflexia. Normally, the reflexic response to cutaneous, visceral (bladder), and proprioceptive stimuli are to some extent attenuated by descending, inhibitory impulses. However, in patients with SCI, these impulses may be curtailed, leading to uninhibited spinal cord reflexes and consequent […]
Definition Initial treatment of atrial flutter targets the rate control (which is frequently ~150 BPM). Drugs of choice include beta blockers such as esmolol (0.5 mg/kg IV bolus followed by 50-300 ucg/kg/min) and propranolol, or calcium channel blockers such as verapamil (5-10 mg IV) or diltiazem. Beta blockers and CCB are effective in prophylactic prevention […]
Definition Common causes include : Down syndrome Rheumatoid Arthritis Trauma Ankylosing spondylitis There are many potential causes of atlantoaxial instability. They are listed below with most common ones listed in bold: Rheumatoid Arthritis Achondroplasia Down Syndrome (occurs less frequently than atlantooccipital instability 10-20% vs 60%) (1) Grisel Syndrome Morquio Syndrome Congenital scoliosis Osteogenesis imperfecta Neurofibromatosis […]
Definition The presence of atelectasis during the perioperative period is likely a multifactorial process. Possible etiologies include the following: Compression: The properties of the thorax and lung change leading to decreased compliance and decreases FRC (decreased by 1 L supine + 0.4 L during general anesthesia). As the low lung volumes approach residual volume, small […]
Definition The use of carboprost (Hemabate) should be avoided in patients with asthma. As stated in the drug information packaging: In patients with a history of asthma, hypo- or hypertension, cardiovascular, renal, or hepatic disease, anemia, jaundice, diabetes, or epilepsy, Hemabate should be used cautiously. There have since been a few case reports of bronchospasm […]
Definition The first sign of salicylate toxicity is often hyperventilation and respiratory alkalosis due to medullary stimulation. Metabolic acidosis follows, and an increased anion gap results from accumulation of intracellular lactate as well as excretion of bicarbonate by the kidney to compensate for respiratory alkalosis. Initial ABG testing often reveals this mixed respiratory alkalosis and […]
Definition Low-dose, long-term aspirin use irreversibly blocks the formation of thromboxane A2 in platelets, producing an inhibitory effect on platelet aggregation. Subspecialty General Related Media Keyword history 96%/2008 See Also: Sources Aspirin and Heart Disease, American Heart Association, Accessed 2/27/15. PubMed
Definition The patient should be placed in the head-down position, oxygen 100% administered, anesthesia deepened, suctioning performed and the severity of the regurgitation/aspiration event assessed fibreoptically. The decision about whether to intubate the trachea or continue with the LMA will depend on how well the LMA is functioning, the severity of the regurgitation/aspiration event and […]
Definition Ascites imposes a restrictive load on the thoracic cage indirectly by the additional weight caused by abdominal swelling from intraperitoneal fluid. This additional load impedes movement of the diaphragm when these patients are in the supine position. The condition creates a type of restrictive lung disease characterized by decreased lung compliance due to extrinsic […]
Definition Bellows are classified according to their movement during EXPIRATION. Ascending bellows rise during expiration and descending bellows fall during expiration. Most modern anesthesia machines have ascending bellows because they are thought to be safer. Ascending bellows are safer because if a circuit disconnection occurs, the bellows will not fill. If there is a complete […]
Definition ASA 1: No organic pathology or patients in whom the pathological process is localized and does not cause any systemic disturbance or abnormality. ASA 2: A moderate but definite systemic disturbance. Examples: Mild diabetes. Functional capacity I or IIa. Psychotic patients unable to care for themselves. Mild acidosis. Anemia moderate. Septic or acute pharyngitis. […]
Definition Except as noted, guidelines apply to both moderate and deep sedation. 1. Preprocedure evaluation Relevant history (major organ systems, sedation–anesthesia history, medications, allergies, last oral intake). Focused physical examination (to include heart, lungs, airway. Laboratory testing guided by underlying conditions and possible effect on patient management. Findings confirmed immediately before sedation. 2. Patient counseling […]
As the arterial pressure wave travels from the central aorta to the periphery, the arterial upstroke becomes steeper, the systolic peak becomes higher, the dicrotic notch appears later, the diastolic wave becomes more prominent, and end-diastolic pressure becomes lower. Thus, when compared with central aortic pressure, peripheral arterial waveforms have higher systolic pressure, lower diastolic […]
Definition According to Miller, “Prone positioning is fraught with difficulty” and can result in accidental extubation, dislodgement of the line or chest tube, and patient injury, “but it can lead to higher functional residual capacity, better drainage of secretions, and improved oxygenation.” Gattinoni and colleagues performed a multicenter, prospective randomized trial in patients with ARDS […]
Definition The Acute Respiratory Distress Syndrome Network (ARDS Net) has performed a number of well executed clinical trials designed to provide an evidence base for the care of patients with Acute Lung Injury (ALI) and ARDS. Note: ALI and ARDS exist on a continuum and may be due to a variety of etiologies (aspiration, bacterial […]
Definition Aortic stenosis is the most common cardiac valve lesion in the United States. The underlying cause is progressive calcification and sclerosis of the aortic valve leaflets, due either to a congenital condition (Bicuspid Aortic Valve is found in 1-2% of the population), or as a natural part of the ageing process. The classic triad […]
Definition Aortic Stenosis Aortic stenosis is the most common cardiac valve lesion in the United States. The underlying cause is progressive calcification and sclerosis of the aortic valve leaflets, due either to a congenital condition (Bicuspid Aortic Valve is found in 1-2% of the population), or as a natural part of the ageing process. The […]
Definition Aortic insufficiency produces volume overload of the LV and the effective forward SV is reduced due to the backward flow of blood into the LV during diastole. With chronic AI, the LV progressively dilates and undergoes eccentric hypertrophy. The resulting increase in end-diastolic volume maintains an effective SV because the end-systolic volume is unchanged. […]
Definition Aortic insufficiency (AI) or regurgitation (AR) may be acute or chronic in nature. Infective endocarditis involving the aortic valve, trauma to the aortic valve and acute aortic dissection are well-described causes of acute AR. The etiologies of chronic AR include connective tissue diseases such as Marfan syndrome and Ehlers-Danlos syndrome, bicuspid aortic valve, and […]
Definition Complications: If the cross-clamp is suprarenal, can have renal failure, hepatic ischemia and coagulopathy, bowel infarction, and paraplegia. Most consistent response is arterial hypertension above the clamp and hypotension below the clamp. Hypertension is due to increase in afterload (systolic ventricular wall tension). Other consequences of cross clamping include : increased segmental wall motion […]
Definition Surgery on the descending aorta almost always involves the application of a cross-clamp so the surgeon is able to sew a graft to it. As a general rule, the more proximal the clamp is placed to the heart, the greater amount of stress it places on the heart. This can loosely be defined as […]
Definition Common Antiplatelet Drugs Keyword history 71%/2012 See Also: Aspirin: platelet effect Sources PubMed
Organophosphate compounds are used as commercial insecticides (isulfoton, phorate, dimethoate, ciodrin, dichlorvos, dioxathion, ruelene, carbophenothion, supona, tepp, epn, hetp, parathion, malathion, ronnel, coumaphos, diazinon, trichlorfon, paraoxon, potasan, dimefox, mipafox, schradan, sevin, and dimetonor) in chemical warfare (nerve gases such as tabun and sarin) and are applied as aerosols or dusts. They can be rapidly absorbed […]
Definition History of cough or dyspnea with supine positioning must be investigated. Tumors (thymoma, teratoma, thyroid CA, lymphoma, hygroma, cyst) of the anterior mediastinum cause obstruction of three structures: the tracheobronchial tree, the main PA (and atria) and the SVC. If the patient can tolerate the supine position, a CT scan should be obtained to […]
Definition Occlusion of the anterior cerebral artery is uncommon, representing only 2% of ischemic strokes.Thus, occlusion of the (ACA) will result in leg weakness. Understanding the impact of an ACA stroke requires a knowledge of the cerebral anatomy and understanding of the motor homunculus. The ACAn supply blood to most medial portions of frontal lobes […]
Definition Ankylosing spondylitis is a chronic inflammatory disease (mostly in males, associated with uveitis and vasculitis / aortic insufficiency) and leading to ossification of the axial ligaments, SI joints, and subsequent fusion of the axial skeleton. These patients are challenging regardless of the anesthesia technique chosen – general anesthesia is complicated by difficulties with airway […]
Definition The nerve supply of the foot is primarily from the sciatic nerve: 1) The superficial peroneal nerve (L4-S1) is located lateral to the extensor digitorum longus Sensory: dorsum of foot and toes except b/w the great and second toes (deep peroneal n.) Technique: see below, blocked with deep peroneal n. and saphenous n. 2) […]
Definition Rate of uptake is dependent on 1) alveolar ventilation rate 2) partial pressure of gas (concentration effect) 3) breathing system For poorly soluble anesthetic agents (ex. N2O, desflurane), an increase in FA/Fi depends very little on alveolar ventilation. For soluble anesthetic agents (ex. isoflurane), an increase in FA/Fi depends significantly on alveolar ventilation. Blood […]
Definition In general a right-to-left intracardiac shunt or transpulmonary shunt will slow the rate of inhalational induction of anesthesia. This occurs because of a dilutional effect of shunted blood, which contains no volatile anesthetic, on the arterial anesthetic partial pressure coming from ventilated alveoli. The impact of a right-to-left shunt on the rate of increase […]
Definition Systemic absorption of LA is determined by site of injection, dosage and volume, addition of vasoconstricting additives, and pharmacologic profile of LA. Blood levels after injection of LA are highest for intercostal blocks > caudal> epidural> brachial plexus> sciatic/femoral> subcutaneous. (See table below.) The more vascular the region the higher the blood levels after […]
Definition In addition to abuse of IV agents, including propofol, [Wischmeyer et al], abuse of volatile agents has also been documents [Zacny and Galinkin]. It is estimated that the incidence of substance abuse among physicians is 2.1% annually (or 7.9% over one’s lifetime) [Hughes]. Drug abuse in anesthesiologists is estimated to be between 1 and […]
Definition All volatile halogenated agents cause dose-related relaxation of the uterus which may lead to increased blood loss during cesarean section. From induction to delivery of the infant 1.0 MAC is given to avoid maternal awareness. After delivery, volatile anesthetics are decreased to 0.5 – 0.75 MAC and oxytocin is given concurrently to decrease the […]
Definition Labor is defined as progressive cervical dilatation in association with uterine contractions. Labor can be divided into the following stages: Stage I: Latent phase Variable duration Starts at onset of labor Complete when the rate of cervical dilation increases (~ 3 cm) Active phase (contractions every 2-3 mins, last 1 min, up to 70 […]
Definition Electroconvulsive therapy (ECT) is a procedure where a generalized epileptic seizure is purposely induced for the treatment of psychiatric disorders (including acute and chronic depression/mania) that are resistant to medical management. The initial reaction following application of the electric current is a parasympathetic response resulting in bradydysrhythmias and possibly sinus pause (1,2). The parasympathetic […]
Definition If intraoperative wheezing should develop, nonbronchospastic causes of wheezing (mechanical obstruction of the endotracheal tube, endo- bronchial intubation, pulmonary aspiration, pulmonary embolism, pulmonary oedema, tension pneumothorax, and negative pressure inspiration) must be ruled out. The first step is to deepen the level of anaesthesia via the i.v. or inhalational route or both. Administration of […]
Definition Considerations include: Prevent elevated IOP (normal 10-22mmHg) and extrusion of ocular contents Avoid retro bulbar block can cause extrusion Avoid coughing/ premature DL Sux can increase IOP slightly Avoid N2O Decreases IOP: Volatile anes, barbiturates, lidocaine, narcotics, Nondepolarizing NMB If full stomach: RSI with rocuronium Subspecialty General Related Media Keyword history 87%/2012 87%/2009 See […]
Definition According to Miller, pharmacologic agents with the potential to increase intraocular pressure include succinylcholine, ketamine, and nitrous oxide. The increase after SCh peaks by 4 minutes and resolves by 6 minutes. Data regarding the attenuation of this increase following precurarization are mixed. Libonati et al. administered SCh to 73 patients with penetrating eye injuries […]
Definition When anemia develops chronically, over a prolonged period of time, and blood volume is maintained, there are four primary mechanisms of compensation. Increased cardiac output: The two principal determinants of SVR are vascular tone and viscosity of blood and in isovolemic hemodilution from chronic anemia, the hematocrit decreases and reduces SVR through decreased viscosity […]
Definition The ACLS dose of epinephrine is 1 mg IV. Similarly, the recommendation for anesthesia providers treating anaphylactic shock in the OR is 0.5 to 1.0 mg. Treatment for hypotension or bronchospasm – 10 to 50mcg increments, repeat as needed with escalating doses. In addition to epinephrine, treatment recommendations for anaphylaxis include stopping any possible […]
Definition Epidemiology: rare (1:20,000 deliveries) but potentially lethal complication (86% mortality rate in some series) Time Frame: Amniotic fluid embolism can occur during labor, delivery, cesarean section, or postpartum. Mortality: Exceeds 50% in the first hour. Etiology: Entry of amniotic fluid into the maternal circulation through any break in the uteroplacental membranes. These breaks may […]
Definition Description: Amiodarone is an antiarrhythmic used to treat different types of tachyarrhythmias. Electrophysiology: Class III antiarrhythmic (prolongs repolarization); lengthens cardiac action potential, negative chronotropic effect in nodal tissues, blocks myocardial K and Ca channels –> slows conduction speed in SA node, causes prolongation of refractory period. Hemodynamic effects: IV amiodarone has a negative inotropic […]
Definition Mechanism of Action — Unclear (thought to be due to an anti-sympathethic and calcium blocking action) Effects — antiarrhythmogenic Time to onset — within the hour of IV administration Major adverse effects — hypotension and bradycardia (which both can be prevented by slowing down the rate of the infusion). Subspecialty General Related Media Keyword […]
Definition Amiloride is one of the four potassium sparing diuretics (others include spironolactone, eplerenone, and triamterene). Amiloride is most like triamterene in that they are both cations that directly decrease sodium channel activity in the principal cells in the cortical collecting tubule. Inhibition of sodium reabsorption at the cationic site prevents the secretion of potassium […]
Definition A K+ sparing diuretic with weak natriuretic and antihypertensive properties inhibits the epithelial Na channel (ENaC) in the late distal convoluted tubule and connecting tubules of the nephron (where 1-2% of total Na reabsorption occurs), effectively inhibiting Na reabsorption at this point. This creates an increased osmolarity in the nephron lumen compared to the […]
Definition In today’s ambulatory surgery centers, more complex surgical procedures are being safely performed while providing a clear economic benefit in an era of cost containment. The development of improved anesthetics and minimally invasive surgical techniques have made the growth of ambulatory surgery possible. These advances have helped to decrease hospital resource utilization, morbidity and […]
Definition Preoperative Female gender Increasing age Congestive heart failure Intraoperative Long duration of surgery General anesthesia Spinal anesthesia Postoperative Postoperative nausea and vomiting Moderate-to-severe pain Excess drowsiness No escort Subspecialty General Keyword history 89%/2012
Definition Pediatric Airway Anatomy Obligate Nasal Breathers Large Tongue Large Occiput Larynx and Trachea are funnel shaped Vocal Cords slant anteriorly Larynx located higher in neck (at C4 vs. C6 in adults) Narrowest part of the pediatric airway is at cricoid cartilage (until age 5). In adults the narrowest part is at the glottis opening […]
Definition The larynx is composed of nine cartilages, three paired and three unpaired and these cartilages contain within them the vocal cords. The movements of the larynx are controlled by the extrinsic muscles which move the larynx as a whole and the intrinsic muscles which move the various cartilages in relation to one another. The […]
Definition In 2013 the ASA Task Force updated their practice advisory on operating room fires (referenced below). Background There are an estimated 50-200 operating room fires annually in the United States including airway and non-airway fires. A fire requires three components known as the “fire triad” including: an oxidizer, ignition source, and fuel. Oxidizers in […]
Definition In 2013 the ASA Task Force updated their practice advisory on operating room fires (referenced below). Background There are an estimated 50-200 operating room fires annually in the United States including airway and non-airway fires. A fire requires three components known as the “fire triad” including: an oxidizer, ignition source, and fuel. Oxidizers in […]
Functional residual capacity equals end-expiratory lung volume in normal patients. Air trapping develops when air remains in alveolae at the end of expiration. In this case, alveolar pressure remains positive, a condition known as intrinsic PEEP or auto-PEEP. Auto-PEEP can be due to either: flow restriction (as in chronic obstructive pulmonary disease) insufficient time for […]
Definition Treatment of air embolism includes discontinuation of nitrous oxide, aspiration through a right heart catheter, adequate supplementation of inspired oxygen, and prevention of further air entry into the circulation (flooding the field with saline, jugular compression and lowering the head in neurosurgical cases). Previous studies have shown that left lateral decubitus position may be […]
Definition An air embolism can be deteced many different ways. Doppler ultrasound: most sensitive noninvasive monitor capable of detecting 0.05ml/kg of air. Transesophageal echo (TEE): most sensitive invasive monitor can detect as little as 0.02ml/kg of air. PA Catheter – increase PAP. Increase ET N2 Decrease ETCO2 due to increase in functional dead space. […]
Definition Similar to pacemakers, sensing problems, lead migration, and battery failure all occur in AICDs (usually within 3 months of implantation). A potential malfunction unique to the AICD is the inappropriate or lack of defibrillation of the device. Any of the above causes can lead to inappropriate therapy. The AICD may discharge inappropriately in response […]
Definition Age-Related Changes Elasticity is decreased in lung tissues causing Over distention of alveoli- Decreases alveolar surface area and decreases gas exchange efficiency. Collapse of smaller airways resulting in increased residual volume and closing capacity. Increase anatomical dead space Increased physiological dead space Increased chest wall rigidity Decreased cough response Decreased maximal breathing capacity Blunted […]
Definition It is important to distinguish between changes in physiology that normally accompany aging and the pathophysiology of diseases common in the geriatric population. For example, atherosclerosis is pathological: it is not present in healthy elderly patients. On the other hand, a reduction in arterial elasticity caused by fibrosis of the media is part of […]
Definition According to Miller, “It has been speculated that general anesthesia and surgery may increase the risk for aggravation of MS. At present, there is no general consensus on this matter, and patients should therefore be informed of the potential for aggravated symptoms in the postoperative period” (p 1172), and “There has been no documented […]
Definition Addison’s disease (a primary adrenal insufficiency) is the loss or degradation of the adrenal cortex resulting in glucocorticoid and mineralocorticoid deficiency. Signs and symptoms include weakness, weight loss, joint pain, postural hypotension, headache, anorexia, constipation, diarrhea, hyperpigmentation, hyponatremia, hyperkalemia, hypoglycemia, and hypercalcemia. The most common culprit in the United States is an autoimmune process, […]
Definition Addison’s disease, or primary adrenal insufficiency, is distinguished from other types of adrenal insufficiency in that the primary problem comes from the inability of the adrenal glands to produce sufficient levels of cortisol, and at times, aldosterone. Primary adrenal insufficiency is usually not apparent until 90% of the adrenal cortex has been destroyed. The […]
Definition Addiction risk factors include : Easy access to potent drugs, particularly opioids The highly addictive potential of accessible drugs, particularly fentanyl and sufentanil Diversion of these agents is relatively simple since only small doses will initially provide the effect desired by the abuser Curiosity about patients’ experiences with these substances Control-oriented personality Subspecialty Related […]
Definition Definition: A behavioral syndrome characterized by evidence of psychological dependence (craving), uncontrolled/compulsive drug use despite harmful side effects, and other drug-related aberrant behavior (e.g., altering prescriptions, manipulating health care providers, drug hoarding or sales, unsanctioned dose escalation). Prevalence: Opioid addiction is as high as 50% in patients with chronic nonmalignant pain. 7.7% in patients […]
Definition Acute mountain sickness (AMS) is diagnosed clinically in a person who lives at low altitude but has recently ascended to high altitude (generally over 2000 M). Symptoms resemble those of an alcohol hangover: primarily headache often associated with fatigue, light-headedness, anorexia, nausea and vomiting, disturbed sleep, and mild shortness of breath with exertion. Onset […]
Definition Non-Anion Gap Metabolic Acidosis – USED CRAP Ureteroenterostomy/Ureterosigmoid connection- either because of surgical ureteral sigmoidostomy or a ureterosigmoid fistula as may occur in Crohn’s disease Small bowel fistula, steroid excess (Addison’s disease, iatrongenic) Extra chloride (NH4Cl or amino acid chlorides 2° to TPN) Diarrhea Carbonic Anhydrase inhibitors, CaCl ingestion, cholestyramine ingestion RTA types I […]
Definition Acetazolamide Acetazolamide is a reversible inhibitor of the carbonic anhydrase enzyme that results in reduction of hydrogen ion secretion at the renal tubule and an increased renal excretion of sodium, potassium, bicarbonate, and water. It can be used as a diuretic or to treat glaucoma as it prevents excessive build up of aqueous humor. […]
Definition Background Effective analgesic and antipyretic with minimal anti-inflammatory properties. Two theories are proposed for its poor anti-inflammatory action – first, it is thought to be predominantly active in the brain, and second, it appears to be unable to inhibit COX in the presence of peroxides, which are abundant at sites of inflammation. Peak plasma […]
Definition Salicylates inhibit the citric acid cycle and uncouple oxidative phosphorylation. Inhibition of these ATP-dependent processes results in: Increased O2 consumption Increased CO2 production Enhanced glycolytic and lipolytic metabolism Depletion of hepatic glycogen Hyperpyrexia Effects on Acid-Base Status Effects of salicylate toxicity vary based on the dose and age of the patient. Direct stimulation of […]
Definition A combined respiratory acidosis / metabolic alkalosis will result in elevated PaCO2 and serum bicarbonate. Which process is the primary disorder (e.g. primary respiratory acidosis with metabolic compensation versus primary metabolic alkalosis with respiratory compensation) is dependent on the pH – in an acidotic patient, the acidosis is primary (and the alkalosis is compensatory) […]
Definition Most commonly shows hypoxemia and hypocapnea (respiratory alkalosis) due to hyperventilation, keep in mind, however, that despite these “classic” findings, arterial blood gas analysis is NOT useful in diagnosis of pulmonary embolism. The more massive the obstruction, the more severe the hypoxemia is likely to be, with an SpO2 < 95% on room air […]
Definition During the first trimester of pregnancy the arterial oxygenation increases from nonpregnant levels to 107 mmHg due to greater alveolar ventilation, the decline in PaCO2, and a lower AV oxygen difference (reducing the reduction in PaO2 due to venous admixture). Throughout pregnancy oxygen consumption increases and cardiac output increases to a lesser extent, lowering […]
Definition Opioid consumption produces a respiratory acidosis (accumulation of CO2). Chronic opioid users may excrete Cl- (classically thought of as “retaining bicarbonate” although in reality is is the loss of the strong anion that matters from a pH perspective, see the work of Kellum J re: strong ion difference and its relationship to pH) in […]
Definition Morbid obesity is associated with OSA, and the concern would be development of respiratory acidosis from hypoventilation. But vomiting causes a metabolic alkalosis. So the result is a mixed resp acidosis with superimposed metabolic alkalosis. The danger is that the alkalemia will reduce the acidemic stimulus to breathe, worsening the pulmonary insufficiency. Subspecialty […]
Definition Speed of recovery from inhalational GA is directly proportionate to alveolar ventilation but inversely proportionate to the solubility of the agent. As the duration of the anesthetic increases emergence becomes dependent on total tissue uptake and average concentration used. Recovery therefore is fastest with desflurane and nitrous, longest with halothane and enflurane. Hypoventilation delays […]
Definition COPD’s pathology includes loss of tissue elasticity, emphysematous bullae, small airway obstruction, and destruction of lung parenchyma. Persons with COPD are typically separated into one of two catagories: “pink puffers” (normal PaCO2, PaO2 > 60 mmHg) or “blue bloaters” (PaCO2 > 45 mmHg, PaO2 < 60 mmHg). Pink puffers have severe emphysema, and characteristically […]
Definition In a compensated respiratory acidosis, although the PCO2 is high, the pH is within normal range. The kidneys compensate for a respiratory acidosis by tubular cells reabsorbing more HCO3 from the tubular fluid, collecting duct cells secreting more H+ and generating more HCO3, and ammoniagenesis leading to increased formation of the NH3 buffer. Compensated […]
Definition Patient Population: Occurs predominately in patients in profound shock, in patients requiring large amounts of vasopressors, resuscitation fluids and blood (more than 6 L of crystalloid or 6 units of packed red blood cells over a 6-hour period – Ref 1), in patients who require abdominal packing for abbreviated/staged laparotomy, and in those with […]
Definition As distance from the sea level increases, barometric pressure of the air falls; however, the O2 concentration remains unchanged as does water vapor pressure. At sea level barometric pressure is 760mmHg, with 47mmHg vapor pressure, leaving PO2 as 0.21 * (760-47) ≈ 150mmHg. At 19,000ft (Mount Kilimanjaro) the barometric pressure is 380mmHg and thus […]
Definition When looking at the brachial plexus just above the clavicle, you will see the subclavian artery medially and the middle scalene muscle (MSM) lateral to the plexus. The plexus will appear as a cluster of hypoechoic round nodules (e.g., “grapes”) just lateral and superficial to the artery. The rib and pleura will be deep […]
Definition Transurethral resection of the prostate (TURP) is commonly performed in males > 60 years of age and utilizes a cystoscope with a wire loop. Continuous irrigation is used to distend the bladder and to remove dissected tissue. Because of the large venous sinuses present in the prostate, irrigation fluid is absorbed into the systemic […]
Definition Transurethral Resection of the Prostate (TURP) typically utilizes large volumes of irrigation fluids for distension and irrigation during the procedure. Historically, these fluids were slightly hyposomolar solutions of glycine, sorbitol, or glucose. Importantly, these fluids are non-conductive (non-electrolyte containing) and are able to be used with monopolar resectoscopes. During prostate resection, exposure of the […]
Definition TURP = Transurethral resection of prostate Traditionally, distilled water was used as irrigation fluid but fell out of practice due to dilutional hyponatremia and intravascular RBC hemolysis. If monopolar probe is used, LR and NS cannot be used due to current dispersion. NS can be used if bipolar or laser probe is used and […]
Definition Trigeminal neuralgia or (tic dolereaux) is characterized by intense, stabbing pain in the distribution of the trigeminal nerve. The trigeminal nerve is mostly a sensory nerve its only motor function being the muscles of masctication. It is divided into the ophthalmic, maxillary and mandibular divisions. The three divisions join and form the Gasserion ganglion […]
Definition Standard ASA monitors as well as an arterial catheter should be placed. Ideally, the arterial catheter should be placed pre-induction, but in a true emergent craniotomy, this may have to be placed post-induction. Central venous access may be indicated depending on the patient’s hemodynamic stability and should be considered on a case by case […]
Definition Transfusion reactions can be broadly categorized into three categories: Hemolytic, Delayed Hemolytic, and Nonhemolytic transfusion reactions. Typical signs and symptoms of a hemolytic transfusion reaction include chest and flank pain, nausea, and chills. These can be masked while under general anesthesia and so, more useful indicators include fever, hypotension, or red colored urine (a […]
Definition Although leukocytes are a normal inclusion with whole blood collection they are actually considered a contaminant of the other blood components such as PRBC’s and platelets. They have increasingly been recognized as the cause or contributors to many transfusion reactions such as immunologically-mediated effects, infectious disease transmission (CMV) and reperfusion injury. Of these reactions […]
Definition Thyroxicosis is a hypermetabolic state occurring when there is an overabundance of circulating thyroid hormone (T3/T4). The condition has several common causes including Graves’ Disease, thyroid nodule, thyroiditis, amiodarone, and post-partum thyroiditis. Treatment begins with antithyroid medications followed by potentially surgical excision or radioactive iodine therapy. Antithyroid agents Thyrostatic medications (carbimazole, methimazole, propylthiouracil) inhibit […]
Definition The recurrent laryngeal nerve provides motor innervation to all intrinsic laryngeal muscles except the cricothyroid muscle. Intraoperative monitoring of the recurrent laryngeal nerve during thyroid surgery is possible with the use of an ETT with two electrodes embedded in its side. The recording electrodes are positioned at the level of the vocal cords. Goals […]
Definition Tetanus is caused by a neurotoxin from Clostridium tetani (gram positive bacillus). Hallmark symptoms of tetanus are muscle rigidity, spasms and in severe cases autonomic nervous system disturbances. C. tetani is ubiquitous in the environment and survives as spores until encountering anaerobic conditions. Tetanus is preferentially taken up by motor neurons and transported retrograde […]
Definition Transcatheter aortic valve implantation is becoming a popular option for patients with severe aortic stenosis who are poor surgical candidates. The procedure is less invasive than open aortic valve replacement; however, perioperative complications from this procedure can be serious and life-threatening. Vascular access is usually obtained via the common femoral artery; the prosthetic valve […]
Definition Heart failure can be categorized multiple ways. One of the most common ways is to classify systolic versus diastolic dysfunction. Approximately half of patients presenting with symptoms of CHF exhibit a near normal systolic function but have impaired diastolic function. Having diastolic dysfunction is categorized by failure of relaxation or filling of the ventricles. […]
Definition Treatment of symptomatic bradycardia is largely algorithm-based, regardless of cause. Acting quickly to treat the bradycardia takes precedence over determining the cause. Once you have initiated treatment, proceed to determine the cause and correct, if possible (See section on “Management of Bradycardia in the OR”). Decide whether the patient has adequate or poor perfusion, […]
Definition The peripheral sympathetic nervous system arises from intermediolateral column of the spinal cord. The efferent preganglionic fibers exit the spinal cord through the ventral roots from T1 – L2. These fibers travel through the white rami communicantes to enter the sympathetic chain – 22 paired ganglia that lie along each side of the vertebral […]
Definition Sensitivity refers to the ability of a diagnostic modality (lab test, X-Ray etc.) to correctly identify all patients with the disease. It is defined as the ratio of the proportion of the patients who have the condition of interest and whose test results are positive over the number who have the disease. It is […]
Definition The major advantage of spinal microcatheters is that they allow for smaller, titrated doses of anesthetics to be administered in order to minimize risk of cardiovascular and respiratory complications. These advantages are particularly important in older or high-risk patients who might not tolerate the abrupt sympathectomy that would result from a single-shot spinal. Common […]
Definition The definition of sinus tachycardia is a regular heart rhythm where there is a P wave before every QRS complex where beats per minute are greater than 100. This elevated heart rate is due to increased conduction via the SA node from sympathetic stimulation. Typically, the management of sinus tachycardia consists of diagnosing the […]
Definition Strong ions are cations and anions that exist as charged particles dissociated from their partner ions at physiologic pH. The SID (Strong Ion Difference) is the difference between the positively- and negatively-charged strong ions in plasma. This method of evaluating acid-base disorders was developed to help determine the mechanism of the disorder rather than […]
Definition The sciatic nerve can be blocked above the level of the knee joint. If ultrasound imaging is used, the sciatic nerve can be consistently found at the top center of the popliteal fossa just lateral to the popliteal pulse, before its division into the tibial and common peroneal nerves. The classic intertendinous technique involves […]
Definition The respiratory quotient (RQ) is the ratio of CO2 produced to O2 consumed while food is being metabolized: RQ = CO2 eliminated/O2 consumed Most energy sources are food containing carbon, hydrogen, and oxygen. Examples include fat, carbohydrates, protein, and ethanol. Their metabolism is represented by the equation: CxHyOz + (x + y/4 – z/2) […]
Definition Dead space is the volume of a breath that does not participate in gas exchange. It is ventilation without perfusion. Physiologic or total dead space is the sum of anatomic dead space and alveolar dead space. Anatomic dead space is the volume of gas within the conducting zone (as opposed to the transitional and […]
Definition The incidence of acute renal failure (ARF) after cardiac surgery varies from 1-30% depending on the definition. The risk factors leading to ARF after cardiac surgery have been well characterized. In patients with normal preoperative renal function, risk factors associated with the development of ARF include advanced age, female gender, diabetes, peripheral vascular disease, […]
Definition Ventilator Associated Pneumonia (VAP) is one of the most common acquired infections ICUs. Rates of VAP range from 1 to 10 cases per 1,000 ventilator‐days. VAP mortality may exceed 10%. Patients with VAP require prolonged periods of mechanical ventilation, extended hospital/ICU stay, excess antibiotics, and increased medical costs. VAP occurs when there is bacterial […]
Definition As many as 2% of pregnant women undergo anesthesia for non-obstetric surgery during their pregnancy [Rosen, 1999]. The second trimester is considered the safest time to undergo nonobstetric surgery (once organogensis is completed), but there are still concerns of fetal hypoxia due to increasing metabolic demands and accidental induction of premature labor. In a […]
Definition The ACC/AHA guidelines recommend preoperative ECGs in patients with at least one clinical risk factor undergoing vascular surgical procedures, or patients with known coronary heart disease, peripheral arterial disease, or cerebrovascular disease undergoing at least intermediate-risk surgery. Age older than 65 years, history of heart failure, high cholesterol, angina, MI, or severe valvular disease […]
Definition Hemostasis undergoes major changes in normal pregnancy. These changes contribute in maintaining placental function and preventing excessive bleeding. Most changes in coagulation create a state of hypercoagulability that serves to protect the mother from hemorrhage during delivery. Unfortunately, these changes can also can predispose women to thromboembolism. It is important to note that complications […]
Definition 1. Mallampati Evaluation: The basis of the Mallampati evaluation is to judge the size of the tongue in relation to the oral cavity as the tongue must be displaced for adequate laryngoscopic view. The evaluation is performed with the patient in the seated position and tongue maximally protruded. While traditionally this test has been […]
Definition Occurring in approximately 13% of those receiving a spinal anesthetic, a post spinal backache is postulated to occur secondary to a localized inflammatory response, often associated with a degree of muscle spasm. The backache is usually self-limited, lasting from a few days up to a week. Treatment consists of conservative measures, including hot and […]
Definition Post herpetic neuralgia pain may precede eruption of vesicles by 7 days and usually resolves within 3 months. Post herpetic neuralgia is defined as facial pain in the affected nerve distribution that remains 3 months after skin vesicles resolve. Dorsal root ganglion necrosis, presence of virus in the nerve and atrophy of the dorsal […]
Definition Post-operative nausea and vomiting (PONV) is a very common problem that not only reduces patient satisfaction and comfort, but it also lengthens PACU stays and increases admissions to the hospital. One of the first ways to treat PONV is to anticipate it as a potential problem and to choose a different anesthetic plan. Regional […]
Definition Postoperative vomiting in children (many children affected are unable to vocalize a feeling of nausea) is a common cause of morbidity after surgery. The incidence of vomiting after surgery is likely twice as high as it is in adults. Established factors that place a pediatric patient at risk for POV include patient age > […]
Definition Independent risk factors for POCD include increasing age, lower educational level, and a history of stroke without residual impairment. These risk factors are believed to indicate a decreased cognitive reserve that puts the patient at risk. POCD is common in adult patients of all ages, but patients older than 60 years of age are […]
Definition Fetal capillaries lie in maternal vascular (intervillous) spaces; therefore, they readily exchange substances with maternal blood. Placental exchange happens only through diffusion, bulk flow, active transport (including certain ions) and pinocytosis. In general, drugs with a MW <500 Da easily cross the placenta unless they are highly ionized, and most drugs with MW >1000 […]
Definition Background Succinylcholine is comprised of two acetylcholine molecules joined together and acts as a depolarizing neuromuscular blocker by binding acetylcholine receptors at the post-synaptic neuromuscular junction end plate. The resultant end plate depolarization initially stimulates muscle contraction; however, because succinylcholine is not degraded by acetylcholinesterase, it remains in the neuromuscular junction to cause continuous […]
Definition With aging, decreased muscle mass and increased body fat result in overall decrease in total body water. Thus, lipid-soluble drugs have higher plasma concentrations and water-soluble drugs have lower concentrations. Also, GFR and hepatic function decline resulting in increased duration of action of several common anesthetics (see below). Protein binding via albumin is usually […]
Definition Acute kidney failure occurs in up to 5% of all hospitalized patients and is associated with increased length of stay, cost, and mortality. Seven independent preoperative predictors have been identified in patients with previously normal renal function (CC >80 ml/min) who developed acute renal failure following surgery. These predictors were identified by a single […]
Definition Surgery and anesthesia lead to a metabolic stress response that causes alterations in the homeostatic mechanisms involved in glucose control. This is particularly true in patients with baseline alterations in glucose management. The stress response includes the release of epinephrine, norepinephrine, cortisol, glucagon, and growth hormone along with inhibition of insulin secretion and action. […]
Definition Periodic paralysis can be sporadic and familial. Familial periodic paralysis shows an autosomal dominant inheritance pattern and is characterized by episodes of flaccid weakness or paralysis with preserved ventilation. This form is often associated with a decrease in serum potassium levels. This is considered a channelopathy in which there is abnormal, potassium-sensitive, muscle membrane […]
Definition In children, the rib cage is oriented horizontally and is highly cartilaginous, moving inward during inspiration. This results in a decreased ability to effectively recruit and use accessory muscles, as well as increased reliance on the diaphragm to maintain tidal volumes. The pediatric diaphragm consists of few (10-25% depending on age) type I muscle […]
Definition Regional analgesia in the pediatric population allows for both excellent postoperative analgesia and attenuation of the stress response in infants and children. Epidural anesthesia can decrease the need for postoperative ventilatilatory support after trachesophageal fistula repair and reduce the complications and costs following open fundoplication. Since the 1990s, there has been a trend towards […]
Definition Surgery is the treatment of choice for symptomatic hyperparathyroidism. Complications of parathyroidectomy include bleeding, recurrent laryngeal nerve injury, and hypoparathyroidism. Unilateral recurrent laryngeal nerve injury presents with postoperative hoarseness. Bilateral nerve injury is a rare but serious complication, resulting in aphonia and requiring immediate intubation. Following parathyroidectomy, serum calcium is expected to decrease within […]
Definition Oxytocic drugs are used for several indications in obstetrics and obstetric anesthesia. These include: The contraction stress test to evaluate fetal well-being during the antepartum period Induction of labor Treatment of labor arrest Active management of labor Treatment of uterine atony and postpartum hemorrhage An anesthesiologist is most likely to give an oxytocic drug […]
Definition Delivery of oxygen can be calculated with the equation: DO2 = CO x CaO2 Where CaO2 = [1.34 x Hgb x SaO2] + [PaO2 x 0.003] The portion contributed by dissolved O2 [PaO2 x 0.003] is usually negligible except in cases of extreme anemia (i.e. Hgb 5) or carbon monoxide poisoning. Factors that affect […]
Definition The equianalgesic conversion ratio for IV to epidural to intrathecal opioids varies depending upon the meningeal permeability of the opioid in question. How lipophilic the drug is, as well as in part by its molecular weight, and possibly structure, affect meningeal permeability. The mechanisms of analgesia for intrathecal opioids result from a direct spinal […]
Definition One-lung ventilation (OLV), or lung isolation, is frequently employed for intrathoracic surgical procedures and is also used in situations where pathology may affect one lung but not the other. Lung isolation may be accomplished by a number of methods including double lumen endotracheal tubes, placement of a bronchial blocker through a single lumen endotracheal […]
Definition Hyperparathyroidism is a common cause of hypercalcemia and the effects of calcium at the neuromuscular junction may cause pre-existing muscle weakness. However, this response is unpredictable and though it might seem that the pre-existing muscle weakness associated with hyperparathyroidism would reduce neuromuscular blocker requirements, it has been suggested that hypercalcemia associated with primary HPT […]
Definition Drugs are rarely indicated in resuscitation of the newly born infant. Bradycardia in the newborn infant is usually the result of inadequate lung inflation or profound hypoxemia, and establishing adequate ventilation is the most important step toward correcting it. If the heart rate remains <60 per minute despite adequate ventilation (usually with endotracheal intubation) […]
Definition The National Practitioner Database (NPDB) is an electronic repository of all payments made on behalf of physicians in connection with medical liability settlements or judgments as well as adverse peer review actions against licenses, clinical privileges, and professional society memberships of physicians and other health care practitioners. According to federal law, information on all […]
Definition Myotonic dystrophy (dystrophia myotonica, DM) is a muscular disorder characterized by prolonged contraction and muscle relaxation, progressive muscle weakness, and wasting. Intraoperative management should aim to avoid triggering myotonia and should take into account that DM patients are at increased risk for the following: Cardiac conduction abnormalities Aspiration Hypersensitivity to anesthetic agents Metabolic abnormalities, […]
Definition A Myelomeningocele results from an abnormality in fusion of the embryologic neural tube during the first month of gestation. The incidence is approximately 1 per 1000. Failure of neural tube closure results in a sac-like herniation of the meninges (meningocele) or a herniation of neural elements (myelomeningocele). Myelomeningoceles most commonly occur in the lumbosacral […]
Definition In the perioperative setting, benzodiazepines are frequently used for anxiolysis, amnesia, and sedation. They exert these effects via the gamma-aminobutyric acid (GABA) neurotransmitter system. In particular, they bind to specific sites on the GABA type A receptor complex, enhancing the interaction between the receptor and chloride ion channel. Benzodiazepines may also be used to […]
Definition Patients cannot be seen because they are generally enveloped by the MRI machine (although remote visualization should be employed, if available). EKG is confounded by artifactual T and ST wave changes (from aortic blood flow) as well as artifacts from the magnetic field. EKG wires must not be coiled. Traditional pulse oximeters cannot be […]
Definition Morbid obesity can be defined by a BMI > 40, or BMI > 35 with comorbid diseases such as DM and hypertension. Obese patients have increased total body weight, with increases in both fat body weight as well as lean body weight. However, the ratio of lean body weight to total body weight decreases […]
Definition Difficult Airway Algorithm Subspecialty General Related Media Keyword history 97%/2014 See Also: Sources PubMed Apfelbaum, et al. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology: 2013, 118(2);251-70
Definition Wolff–Parkinson–White syndrome (WPW) is a ventricular pre-excitation syndrome associated with abnormal conduction pathways between the atria and ventricle. Classic findings on the ECG are the delta wave (slurred upstroke of QRS) and shortened PR interval (<120s). Tachycardias may be narrow complex (associated with anterograde conduction through accessory pathway) or wide complex (associated with retrograde […]
Definition Methemoglobin (MetHb) is altered state of hemoglobin (Hb) in which the ferrous (Fe2+) irons of heme are oxidized to the ferric (Fe3+) state. The ferric hemes of MetHb are UNABLE to bind oxygen (O2). Thus, oxygen dissociation curve is left-shifted, making it more difficult to release O2. Methemoglobinemia types: Congenital – diminished enzymatic reduction […]
Definition Meperidine is a synthetic opioid widely used for treating pain. It is also used for controlling post anesthetic shivering. Its main pharmacological action is produced through μ receptors on the central nervous system (CNS). Meperidine is metabolized extensively in the human liver by 1) N-demethylation to normeperidine (6-N-desmethylmeperidine), which may be further hydrolyzed to […]
Definition Mannitol is an osmotic diuretic that is a six-carbon carbohydrate that undergoes filtration at the glomerulus with limited or no reabsorption in the proximal tubules. It works as osmotic diuretic and is often used to reduce intracranial pressure and treat oliguric renal failure. At large doses mannitol increases excretion of sodium and potassium. Initially, […]
Definition 1. Immediately discontinue anesthetics, including succinylcholine. Life-threatening surgery will be continued, but with the use of a non-triggering anesthetic agent and machine to prevent residual inhalation agent from triggering a second episode. 2. Hyperventilate 100% oxygen at a high flow rate of 10L/min to treat effects of hypercapnia, metabolic acidosis, and increased oxygen consumption […]
Definition The lung is particularly suited to function as a “chemical filter” as it receives 100% of cardiac output and has the largest capillary endothelial surface in the body. It is involved in the modification or uptake of many vasoactive substances and hormones including serotonin, prostaglandins (E1/E2/F2alpha), norepinephrine, bradykinin. It also is the site of […]
Definition The lungs perform several metabolic functions including gas exchange, conversion of angiotensin I to angiotensin II by angiotensin converting enzyme (ACE), inactivation of vasoactive substances, and protein synthesis. Angiotensin converting enzyme is found on the surface of capillary endothelial cells in the lungs. The enzyme catalyzes the conversion of angiotensin I to angiotensin II, […]
Definition The QT interval is normally < 450 ms in males, < 470 ms in females. Prolongation is associated with a risk of the arrhythmia torsades de pointea (TdP), a potentially life threatening ventricular arrhythmia, when drugs that further prolong the QT are administered. Examples of these drug classes are include: Antiarrhythmics: Amiodarone, Satalol, Quinidine, […]
Regression analysis is concerned with relationship between two or more variables. There are many subtypes of regression depending on the variables to be studied and the nature of the relationship of interest. Logistic (or Logit) regression can be used to investigate outcomes that are binomial or categorical (Mortality vs. Survival, Complication vs. None etc). This […]
Definition The onset of local anesthetics are dependent on the anesthetic technique utilized. The shortest onset time is encountered after intrathecal or subcutaneous administration, the longest occurs with peripheral nerve blocks. Variations are due to anatomy and amount of drug utilized. Brachial plexus block is slow since the agent is injected some distance from nerve […]
Definition Lithium salts (most commonly, lithium carbonate) are frequently used to treat bipolar disorder. According to experimental animal data and case reports in humans, lithium can interfere with anesthetic agents and neuromuscular blockers. In an animal model, Hill et al. observed that lithium prolonged the latency (time to onset) and the duration of neuromuscular blockade […]
Definition One of the most feared complications of laser surgery of the larynx is fire in the airway. So-called “regular” endotracheal tubes can present some issues when performing microlaryngeal surgery with a laser. The PVC material on regular ETTs can be damaged with laser use, causing local damage of the mucosa at best, and a […]
Definition 1st Stage of Labor Pain is dull and poorly localized. Uterine contractions release bradykinin, histamine, and serotonin that act on chemoreceptors. This is thought to be the result of myometrial ischemia. Mechanoreceptors are also stimulated from the distension and stretching of the lower uterine segment and cervix which causes impulses to enter the […]
Definition Jet ventilation can be performed via either high or low frequency means. High frequency jet ventilation (HFJV) is accomplished with specialized ventilators capable of producing the high pressure, low volume breaths necessary. Low frequency jet ventilation (LFJV), however, is usually accomplished with a manually triggered hand-held device. HFJV is primarily utilized in an ICU […]
Definition Serum Albumin is a marker of Hepatic Synthetic Capacity. Albumin 1/2-life is 3 weeks, so hypoalbuminemia indicates chronic dysfunction, but won’t be apparent in acute injury. Albumin maldistribution, loss via kidneys, and degredation can also be causes of hypoalbuminemia, so can dilution from increased volume The liver synthesizes 11 blood coagulation proteins, most of which have short […]
Definition Inter-converting between oral and IV opioids is a very common situation encountered in clinical anesthesiology both in the context of treating acute perioperative pain, in the setting of chronic pain management or in combination. In order to determine equivalency between opioid agents, equianalgesic dosing tables are utilized in order to convert dosing between route […]
Definition Blood passing through areas of absolute shunt receives no oxygen (V/Q = 0), therefore, arterial hypoxemia resulting from intrapulmonary shunt is minimally responsive to supplement oxygen. Shunt effect (venous admixture or low V/Q) is the more common clinical scenario in which areas of lung have poor alveolar ventilation compared to the degree of alveolar […]
Definition Anatomy: The brachial plexus arises from the cervical nerves C5 through C8 as well as T1. It originates from the anterior primary rami of these nerves and after leaving their corresponding intervertebral foramina, these nerves run anterolaterally and inferiorly where they end up between the anterior and middle scalene muscles. The anterior scalene muscle […]
Definition Acute Treatment Elevating head of bed to improve venous drainage. Oxygenation and ventilation to keep PaO2 >100, PaCO2 30-35, use lowest possible AW pressures to not impede venous drainage, and keep MAP at pre-intubation level. Mannitol decreases blood viscosity, CBF unchanged while CBV and ICP decrease. Mannitol also reduces ICP by reducing cerebral parenchymal […]
Definition Ilioinguinal nerve The ilioinguinal nerve is a branch of the anterior rami of the L1 spinal nerve that originates in the lumbar plexus. Additionally, the iliohypogastric nerve is a branch of L1 that travels with the ilioinguinal nerve for a distance before branching off to a different destination and innervation. After exiting the lumbar […]
Definition The most common indication for ICD removal or lead extraction is system infection. Other indications include lead malfunction (fracture or failure), lead or device erosion, lead upgrade, retained lead or lead fragment causing potentially life-threatening arrhythmias, or thromboembolic complications or venous obstruction. There are several methods for lead extraction. Traction is the most simple […]
Definition Inhaled anesthetic gases will substantially reduce the body’s ability to vasoconstrict and shiver in order to preserve and generate body heat. They will also reduce the ability of infants to undergo non-shivering thermogenesis. Prevention of hypothermia is necessary, as hypothermia leads to increased risk of infection, myocardial morbidity, and coagulopathies, to name several disadvantages. […]
Definition Phosphate is very important as a source of chemical energy as it forms ATP in all cells. When phosphate is low, muscles do not function well, in particular the respiratory muscles (including the diaphragm). Low serum phosphate does not necessary mean low intracellular phosphate; therefore, it is always important to clinically assess the patient […]
Definition Hyponatremia ([Na+] < 130 mEq/L) is the most common electrolyte abnormality in hospitalized patients and is a relatively common complication after subarchnoid hemorrhage (SAH) with an incidence of 10% to 34%. Occurring, in general, several days after the event, the hyponatremia is caused by either SIADH or cerebral “salt wasting”. Patients who are euvolemic […]
Definition Hyponatremia is defined by the presence of a serum sodium <135 mEq/L. When evaluating low sodium levels, total body water (TBW) must be taken into account as low sodium is almost always due to either increased TBW or loss of sodium in excess of TBW. Measuring the plasma osmolality allows one to divide the […]
Definition Background: Glucagon was originally thought to be a “contaminant” that caused hyperglycemia found in pancreatic extracts in studies from 1923. Looking for the hyperglycemic mechanism of this “contaminant” led to the nobel prize-winning discovery of cyclic adenosine monophosphate (c-AMP) in the 1960s. Full understanding of this hormone did not come until the 1970s, when […]
Cerebral hyperperfusion syndrome is a consequence of cerebral hyperemia and can lead to neuronal disfunction, cerebral edema, and/or intracerebral hemorrhage. Symptoms vary depending on the vascular bed involved, and the syndrome can be fatal in some cases. Cerebral hyperperfusion is thought to result from a failure of autoregulation. It usually occurs in the setting of […]
Definition Hypocarbia exists when PaCO2 is below 35 mmHg, which is typically the result of hyperventilation causing a respiratory alkalosis. Several electrolytes are affected by the increase in pH. Within 5-10 minutes there is drop in plasma [HCO3-] from titration of nonbicarbonate body buffers. Small increases in plasma chloride, lactate, and other unmeasured anions balance […]
Definition Herbal medicines that increase the risk of bleeding: Garlic: inhibits platelet aggregation (organosulfur), discontinue for seven days *Ginkgo: inhibits platelet activating factor (terpenoids, flavonoids), discontinue for thirty six hours. Ginseng: inhibits platelet aggregation and lowers blood glucose (ginsensosides [mimic steroids]). Check PT/PTT/glucose, d/c for 24 hours (preferably seven days) Saw Palmetto: associated with excessive […]
Definition Guillain-Barre Syndrome is characterized as an acute inflammatory demyelinating peripheral polyneuropathy secondary to an autoimmune response in association with an infectious process. Classically the syndrome is described as an ascending paralysis, starting in the legs and progressing cephalad. There are multiple variants of GBS; ascending weakness may or may not be accompanied by dysesthesias […]
Definition Preoperative fasting is used to reduce the risk of pulmonary aspiration. From the ASA guidelines on preoperative fasting, meta-analysis of randomized controlled trials demonstrated in adult patients given clear liquids 2-4 hours before a procedure versus 4 hours had smaller gastric volumes and higher pH values. In children who received clear liquids 2-4 hours […]
Definition Furosemide and venodilation (Sunny Chaio) Furosemide is a loop diuretic that inhibits the Na-K-2Cl symporter in the loop of Henle. It exerts direct vasoactive effects, as well as hormonally mediated changes via release of renin, angiotensin II, and prostaglandins. These result in arterial vasoconstriction and venous vasodilation, as well as diuresis. In heart failure […]
Definition Variable decelerations are the most common type of decelerations and are transient decreases in fetal heart rate that characteristically vary in duration, shape/magnitude, and timing/onset. They correspond with uterine contractions and are likely a result of umbilical cord compression against the fetus leading to decreased umbilical blood flow. They can be classified as mild […]
Definition When an electrical current is applied to the myocardium, electrons present at the outer surface of the myocytes stimulate voltage-dependent sodium channels present within the cell membranes causing rapid cellular depolarization. This wave of depolarization spreads nearly instantaneously through the myocardium, such that any remaining activation wave fronts present within the myocardium reach tissues […]
Definition The depth of anesthesia is dependent on the anesthetic agent’s partial pressure (or tension) in the brain. The goal in giving an inhalation anesthetic is to achieve an adequate partial pressure of anesthetic (Panes) in the brain to cause a desired level of CNS depression to achieve general anesthesia. Inhalation anesthetics move down a […]
Definition Postoperative ileus is almost universal following major abdominal surgery. Nearly 100 years ago, Cannon and Murphy demonstrated that opening the peritoneal cavity and manipulating the intestines resulted in significant inhibition of GI tract contractile function in dogs. It has been suggested that epidural analgesia can shorten the duration of postoperative ileus and thereby decrease […]
Definition The stimulus leads to increases in cerebral blood flow and increased ICP. Initially, the seizure activity causes a large parasympathetic discharge with bradycardia, atrial or ventricular premature beats, and occasional asystole. This is followed by sympathetic discharge causing tachycardia (maximal at two minutes), hypertension, ST-segment depression and T-wave inversion not associated with myocardial enzyme […]
Definition Myxedema coma typically presents as decreased mental status and hypothermia in a patient with either chronic, severe hypothyroidism or any form of hypothyroidism in the setting of a significant physiological stressor (infection, MI, sedative medications/opioids). Patients may also demonstrate hypotension, bradycardia, hypoventilation, hyponatremia, and hypoglycemia. The term “myxedema” refers to non-pitting edema that can […]
Definition Diuretics are routinely used in the treatment of hypertension and congestive heart failure. Several classes of diuretics exist, including thiazide diuretics (HCTZ, metolazone, chlorthalidone), loop diuretics (furosemide and bumetanide), carbonic anhydrase inhibitors (acetazolamide), osmotic diuretics (mannitol), and potassium sparing diuretics (spironolactone, amiloride, and triamterene). The different classes have different mechanisms of action. The thiazide […]
Definition Discogenic pain stems from degenerative disk disease (DDD), occurring without spinal deformity, radicular pain, neurologic symptoms, or spinal stenosis. Often it arises from disruption of the posterior annulus fibrosis that causes an inflammatory response that activate nociceptive nerve terminals. As noted above, the neurological examination is typically normal, but structural exam may reveal limited […]
Definition Dilutional Coagulopathy refers to the coagulopathy seen during massive transfusion for major trauma and/or hemorrhaging. Major trauma and hemorrhage cause coagulation abnormalities due to consumption of coagulation factors and platelets. Dilutional coagulopathy is due to dilution, along with consumption, of platelets during massive transfusion. Large volumes of crystalloid fluid used for resuscitation in these […]
Definition Hemolytic transfusion reactions can be defined as acute or delayed. Both are the result of recipient antibody and complement attack on donor cells. The target and concentration of recipient antibodies differentiates acute from delayed hemolytic transfusion reactions. In contrast to acute hemolytic transfusion reactions which are almost always due to ABO incompatibility, delayed hemolytic […]
- Neuraxial techniques a. Epidural i. Traditional ii. Ultrasound-Guided b. Spinal c. Paravertebral i. Traditional ii. Ultrasound-Guided Single Shot iii. Ultrasound-Guided Catheter 2. Truncal Blocks a. Transversus Abdominis Plane i. Traditional ii. Ultrasound-Guided b. Ilioinguinal/iliohypogastric c. Rectus Sheath Block 3. Peripheral nerve blocks: indications, benefits (outcome studies), when single injection vs catheter a. Basics of […]
Definition The treatment of choice for acute mitral insufficiency is MVR if insufficiency is severe. However, most of these patients need some sort of medical stabilization/treatment. In the acute period, IV vasodilators are the first line of treatment. Specifically, sodium nitroprusside is the most commonly used medication. Nitroprusside will help to vasodilate which will reduce […]
Definition Dalton’s Law, simply stated, is that the total pressure exerted by a mixture of gases (real or ideal) in a fixed volume is equal to the sum of each gases partial pressure. Recall that the partial pressure of a gas is the pressure exerted by that gas on its container independent of any other […]
Definition Treatment of cyanide toxicity should be initiated as soon as it is suspected; do not delay treatment while awaiting formal diagnosis by blood cyanide levels. Primarily, treatment is aimed at uncoupling cyanide from cytochrome oxidase, and allowing cells to return to aerobic metabolism via oxidative phosphorylation. Patients who present with possible exposure (including iatrogenic […]
Definition The concentration effect refers to the principle that the concentration of inspired anesthetic gas influences both (1) the alveolar concentration that may be attained and (2) the rate at which that concentration may be attained. The rate of rise of alveolar end tidal concentration is thus dependent upon and accelerated by a high initial […]
Definition Pregnancy is a state of hypercoagulation, which is likely an adaptive mechanism to reduce the risk of hemorrhage during and after the delivery process. Unfortunately as a result of the hypercoagulable state, thromboembolism is one of the leading causes of death associated with pregnancy, particularly in developed nations, with clinically significant venous thromboembolism occurring […]
Definition Describes the relationship between PCO2 and total CO2 concentration in blood. Three Forms of Carbon Dioxide in the Blood 1. Physically dissolved CO2 (~5%) Henry’s law : dissolved CO2 increases linearly with increases in PCO2 CO2 solubility = 0.06 mL CO2/dL blood/mm Hg (20 times higher than O2 solubility) 2. Carbamino compounds (small) […]
Definition The Clark electrode was invented by Leland Clark after criticism that his bubble oxygenator, which he had invented for use in cardiac surgery, was unable to measure the oxygen tension of the blood returning to the patient from the bypass circuit. The electrode has several components: a platinum cathode (electron receiver), silver anode (electron […]
Definition Cerebral blood flow (CBF) is directly proportional to cerebral metabolic rate (CMR). Cerebral perfusion pressure (CPP) is the difference between the mean arterial pressure (MAP) and intracranial pressure (ICP) or central venous pressure (CVP), whichever is greater. Autoregulation maintains CBF relatively constant between a CPP of 50 and 150 mmHg in normotensive, healthy individuals. […]
Definition Anesthetic goals in this patient population revolve around 1) preventing large changes in blood pressure 2) facilitating surgical exposure [via hyperventilation and osmotic diuresis] 3) ensuring adequate collateral circulation if temporary clips are placed during surgery 4) minimizing deleterious increases in ICP and 5) allowing for rapid wakeup and neurologic examination. As with other […]
The transmural pressure of an aneurysm is related to the difference between the Mean Arterial Pressure (MAP) and Intracranial Pressure (ICP): Transmural Pressure= CPP= MAP – ICP Therefore, an increase in the MAP or an abrupt decrease in ICP leads to an increase in the transmural pressure. Thus, increases in MAP and decreases ICP can […]
Definition Aneurysmal subarachnoid hemorrhage occurs in approximately 1 per 10,000 persons in the United States every year, accounting for 5–15% of all strokes. The overall case fatality of all‐cause SAH is as high as 50%. Aneurysmal SAH carries a 30-day mortality rate of 45%. Of those who survive, nearly 1/3 suffers significant and permanent neurological […]
Definition Clinical findings consistent with cardiac tamponade include tachycardia, dyspnea, chest pain, diaphoresis, decreased arterial pulsation, muffled heart sounds, elevated jugular venous pressure and pulsus paradoxus. Classically Beck’s triad is used to characterize three signs of cardiac tamponade: hypotension, jugular venous distention and muffled heart sounds. Diagnosis of cardiac tamponade relies mainly on index of […]
Definition Preoperative cardiac evaluation of valvular disease helps identify the severity of the valvular defect, the hemodynamic changes from the valvular lesion, and changes in the pulmonary, renal, and hepatic systems as a result from the aberrant valve. Symptoms of decreased ventricular function should be obtained pre-operatively, and then stratified by the New York Heart […]
Definition The World Health Organization has developed a 3-step ladder for pain management in adult cancer patients. This three-step approach of administering the right drug in the right dose at the right time is inexpensive and 80-90% effective. The three steps are as follows: Step 1: Non-opioid analgesics such as ASA, NSAIDs, acetaminophen (+/- adjuvants) […]
Definition Hyper-/Hypocalcemia can cause ECG changes secondary to altered trans-membrane potentials that affect conduction times. (Sources 1,2). Hypercalcemia: The most common ECG findings of hypercalcemia are a short QT interval (Ref. 1) secondary to a shortened ST segment. (Source 3) There may also be a widened or flattened T wave; however, significant hypercalcemia can cause […]
Definition Perioperative and post-operative bradycardia is relatively common during and after heart transplant. Possible etiologies including sympathetic denervation, ischemic injury to the sinus node, and graft ischemia. In the post-operative setting progressive conduction system disease associated with coronary artery disease, chronic rejection, and injury from routine endomyocardial biopsies can all result in AV dysfunction and […]
Definition Pharmacokinetics is the study of how a drug is affected by the body, which includes a drug’s absorption, distribution, metabolism and excretion. Differences in drug effects among patients may be influenced by genetic differences in patients’ ability to respond to a drug. There have been numerous enzymes identified as important to drug metabolism. Genetic […]
Definition Temperature regulation is important in pediatric patients, particularly neonates, as they are prone to greater heat loss in the operating room when compared to adults. This is because of their larger surface area per kilogram, thinner skin and lower fat content. Temperature regulation is made even more difficult in the operating room because of […]
Definition Goals of Cardiopulmonary Bypass Provision of a Surgical Field Myocardial Protection DO2 and RCO2 Temperature Management Glucose Management Prepare for Separation Management of Physiology Pressure Ideal perfusion pressure not known. Cerebral autoregulation from 50-150 mm Hg. Confounded by chronic HTN, advanced age, diabetes. May be as low as 20 mm Hg when hypothermic. Excess […]
Definition Pathophysiology AT3 is known to slowly break up fibrin and factor X. When heparin binds to AT3, AT3 will break up fibrin and factor X faster. AT3 is not dependent on vitamin K so unlike warfarin, giving vitamin K will not reverse the effects of heparin. A. Types Type I antithrombin deficiency complete […]
Definition Normal individuals will have up to 3% CO, and smokers may have up to 9%. Patients are generally asymptomatic if < 10%, with overt signs developing at ~ 15%. Diagnosis The diagnosis of CO poisoning is made by a history of exposure (internal combustion engine exhaust, fire, improperly adjusted gas or oil heating, charcoal […]
Definition Normal individuals will have up to 3% CO, and smokers may have up to 9%. Patients are generally asymptomatic if < 10%, with overt signs developing at ~ 15%. Carboxyhemoglobin Level Symptoms 1-3% Normal nonsmoker 4-9% Smokers 15-20% Overt signs of toxicity (headache, nausea and vomiting, etc.) 20-25% Signs of severe toxicity (seizures, acute […]
Definition The blood brain barrier (BBB) is a specialized barrier that renders the environment of the central nervous system (CNS) separate from other compartments of the body. The unique environment provided by the BBB enables the specialized activity of neurons; BBB breakdown is the result of pathologic conditions and leads to further neuronal dysfunction. The […]
Definition Cerebral autoregulation may be defined as the maintenance of constant cerebral blood flow despite changes in cerebral perfusion pressure, where CPP is equivalent to MAP-ICP (or CVP, whichever is greater). Given that normal ICP is generally low (5-12 mmHg), CPP is mainly dependent upon MAP. The normal range of cerebral autoregulation is often quoted […]
Definition AVMs are abnormal collections of blood vessels with direct arterial to venous connections and no normal intervening capillary circulation. They are typically high-flow, low-resistance. They are believed to be congenital and commonly present in adulthood as hemorrhage or new-onset seizures. Treatment may be a multi-step process, including a combination of surgical intervention/resection, Gamma knife […]
Left Ventricular Preload According to Kaplan, preload is technically defined as ventricular wall stress at end-diastole [Kaplan JA, ed. Essentials of Cardiac Anesthesia. Saunders, 2008 p 60; however, ventricular volume at end-diastole may be a more clinically useful definition – first, it is more easily measured (by echocardiography) and second, it is the geometrical configuration of […]
Mechanism of Action Converted to NO which stimulates cGMP production. Acts as a smooth muscle relaxant and venodilator (why NTG is more of a venodilator than a vasodilator is not known). Note that the process of NO formation is dependent on availability of sulfhydryl (SH) groups and thus tolerance can develop. Hemodynamic Effects Systemic Venodilation […]
Primarily due to the interventricular septum, the pericardium, and the the cardiac fibroskeleton. Also playing a role are pulmonary venous capacitance, RV distensibility, and the transseptal pressure gradient.
The goal of this page is to collect and distribute evidence-based information regarding the perioperative care of patients with a variety of vascular diseases. This page is a Chapter of our Anesthesia Text, which is in turn a Unit of the entire OpenAnesthesia.org wiki. We invite you to make changes as you see fit, but […]
There are four manifestations of COPD that can be (and are often recommended by textbooks to be) treated preoperatively – atelectasis, bronchospasm, pulmonary edema, and respiratory tract infections. Keep in mind, however, that there are no controlled trials which support the use of preoperative β–agonists, aminophylline, antibiotics, hydration, or chest physiotherapy in the COPD population. […]
Introduction The uterine arteries provide the uterus with ~ 700 cc/min of maternal blood. The fetus receives blood through two uterine arteries, and returns it via a single uterine vein. Placental vasculature normally exists in a vasodilated state (although not maximally so, as is classically taught), probably secondary to nitric oxide release. Note that many […]
Release of antidiuretic hormone is a natural response to perioperative stressors, thus it should be expected that urine output will decrease during and after major surgery. Alpert and Roizen showed in 1984 that the lowest intraoperative UOP has absolutely no correlation with post-operative creatinine changes (137 patients undergoing vascular surgery) [Alpert RA et al. Surgery […]
UTIs account for 30% of all nosocomial infections [NEJM 329: 1328, 1993], with catheterization being the most important predisposing factor (4 – 7% risk per day [Am J Med 92S4A: 114, 1992]). The key pathogenic event is loss of Lactobacillus protection. Diagnosis cannot be based on cultures alone because half of all patients with catheters […]
Preanesthesia Resuscitation When resuscitating neurosurgical patients with other trauma, even in the presence of severe head injury, adequate volume resuscitation is far more important than the fear of excessive fluid overload [Andrews] Cardiopulmonary concerns Blood pressure management is controversial – often hypertension is secondary to pain, which should be treated. Other potential causes include cerebral […]
Prehospital Classification Mild injury = GCS 13-15, may be slightly lethargic or confused but can communicate and follow commands. Moderate injury = GCS 9-12, often lethargic or obtunded but arousable to vocal or noxious stimulation. These patients must be evaluated for drug intoxication, hypoxia, hypercarbia, and metabolic abnormalities. Severe injury = GCS 8 or less […]
Trauma increases the risks of spontaneous abortion and preterm labor, thus obstetric consultation should be considered in any traumatized parturient. Furthermore, all women of childbearing age should have their hCG measured, as early pregnancies are often unknown. Pelvic shielding should be provided for all radiographic exams, when available. Fetal heart rate monitoring is indicated if […]
Epidurally administered local anesthetics may decrease both the incidence and severity of post-operative arrhythmias – in Oka et al.’s study of 50 patients randomized to morphine versus bupivacaine epidurals, the incidence of arrhythmias fell from 28% to 4.35% [Oka T et al. Anesth Analg 93: 253, 2001; FREE Full-text at Anesthesia & Analgesia]. Possible mechanisms […]
Trauma outcomes are worse in elderly patients, with one poorly controlled retrospective study suggesting that “elderly” trauma patients are six times as likely to die. [Osler T et al. Am J Surg 156: 537, 1998] This study was complicated by the fact that the “elderly” cohort suffered different injuries than the control group. It is […]
Total Body Water and Volume Urea is freely permeable so elevated BUN can create a hyperosmotic condition but not a hypertonic situation. Measured osmolality is done via the freezing method, whereas calculated = 2 x [Na+] + [BUN]/2.8 [glucose]/18. Normal value is 286 +/- 4. A normal osmolal gap can be as high as 10 […]
Introduction TFTs are abnormal in 70% of hospitalized patients [Arch Intern Med 150: 1249, 1990] and up to 90% of ICU patients [Crit Care Med 22: 1603, 1994]. In most (but not all) cases, these lab abnormalities represent an adaptive response to non-thyroidal illness and are not a sign of thyroid disease. Evaluation of Thyroid […]
Temperature Management During General Anesthesia Adverse Effects of Intraoperative Hypothermia Increased Infection Risk 2-fold risk with 2C drop [Kurz A et al. NEJM 334: 1209, 1996] Increase in Blood Loss/Transfusions EBL increased 500 cc with 1.6C drop [Schmied H et al. Lancet 347: 289, 1996, n = 60], 186 cc with 0.5C [Widman J et […]
Current indications for therapeutic hypothermia in critical care are: Indications for therapeutic hypothermia: Neuroprotection post-cardiac arrest ICP Control Neonatal hypoxic-ischemic encephalopathy Please also see Hypothermia: Cold OR mechanism and Cardiac arrest: Induced hypothermia
Introduction MUST be ruled out in any high-energy trauma. Most common location is distal to the L subclavian artery, probably because the mobile aortic arch is continuous with the immobile descending thoracic aorta at this point (shear stress). Many of these injuries are fatal, however those that survive deserve immediate attention – a 15 year […]
Right Atrium Right atrium receives blood from the SVC, IVC (ostium guarded by the eustacian valve), and coronary sinus (guarded by the Thebesian valve). Fossa ovalis (remnant of foramen ovale) is located in the intraatrial septum. The purpose of the eustachian valve in utero is to direct blood from the IVC across the foramen ovale […]
Process Overview Blood is drained from the vena caval filters directly into a reservoir. Normally a single two-stage cannula is used (drains blood from the RA and the IVC), however if a bloodless heart is required, two cannulae (SVC and IVC) can be used instead. Venous return is dependent on the hydrostatic column between the […]
Even with very large sample sizes, few datasets are perfectly Normal. Nevertheless, it is often many statistical tests assume normality. In order to apply a statistical test that assumes normality (i.e., Student’s t Test (Biostatistics Text)) it is necessary to determine if the data is “sufficiently normal”. In the medical literature, the Kolmogorov–Smirnov test is […]
Right Ventricular Preload 65% of systemic blood is present in the venous system. The systemic veins are an important vascular reservoir, capable of storing blood volume for later use in times of stress – active venoconstriction may add as much as 1L of blood to the circulation [Barash, PG. Clinical Anesthesia, 5th ed. (Philadelphia), p. […]
News SOCCA @ ASA: October 11-15, 2014 (New Orleans, LA) Next SCCM Meeting: January 17-21, 2015 (Phoenix, AZ) Critical Care and Perioperative Medicine Essentials- Exploring the Curriculum Click here to explore the full curriculum About the Author(s) Dr. Thiele is a cardiothoracic and critical care anesthesiologist and primarily practices in the cardiac operating rooms and […]
Intro to SAH Normal MCA velocities are 30-80 cm/s. Only low (< 120 cm/s) or high (> 200 cm/s) absolute velocities consistently correlate with arterial narrowing [Neurosurgery 44: 1237, 1999] – since most patients fall in an intermediate range, invasive treatment should not be based on these values alone. Instead, TCDs should be used as […]
“The Student’s t Test is used to compare the mean of two normally distributed samples, preferably of equal size and variance. More specifically, the Student’s t Test gives you a probabilistic estimate of the likelihood that your samples were randomly selected from the same population, i.e. that the Null Hypothesis is true. If the Student’s […]
Necessarily leads to decreased stroke volume and cardiac output, causing a sympathetic response. Critical to understand is that positive pressure ventilation, combined with tamponade, can further reduce preload and actually cause catastrophic hypotension and even cardiac death. Thus, NEVER initiate positive pressure ventilation until the pericardial space has been drained – if general anesthesia is […]
Tachyarrhythmias are either the result of 1) increased automaticity 2) triggered activity or 3) reentry. Reentry is the most common clinically significant etiology. Tachyarrhythmias can also be classified as SVT (normal QRS) or ventricular (QRS > 0.12s). Algorithm / Suggestions for Accurate Diagnosis Narrow Complex Tachyarrhythmias (QRS < 0.12s) First look at the rhythm and […]
Whipple Preoperative Evaluation and Questions: 5-year survival rate is 15% – 25% (versus 1% – 5% with no cancer-directed treatment) [Marandola M et al. Transplantation Proceedings 40: 1195, 2008]. Electrolyte abnormalities are common in patients with abdominal pain or vomiting, thus consider a preoperative chem-7. Blood products available + Ranger / rapid infuser. Risk: operative […]
Prehospital Incidence and Background The incidence of cervical spine injury is only 1-3% in adult head trauma, and 0.5% in children, however because of the prevalence of trauma, there are 10,000 SCI per year, 3500 of which lead to complete neurologic deficit. Most common locations for SCI are lower cervical or upper lumber, areas of […]
Lung Volumes Normal tidal volume is 6-8 cc/kg. Normal vital capacity is 60 cc/kg +/- 20% (i.e. 10-fold increase of TV), and is correlated with the ability to cough and take deep breaths. Inspiratory capacity (IC, the maximal volume inspired from FRC) is one of the only tests that can detect extrathoracic airway obstruction. FRC […]
Spinal Cord Injury Anesthetic Considerations Many authors recommend awake fiberoptic intubation as a safe alternative to DL in patients with cervical cord injuries – Schwartz et. al reported a series of 327 patients with cervical lesions who received nasal/oral fiberoptic intubation with 100% success rate. In 12 patients (3.6%), anatomic abnormalities transnasal endotracheal intubation and […]
Updated 09/14/2015 by Susan M. Lee, MD Smoking and Anesthesia/Surgery An estimated 42.1 million U.S. adults (almost 18% of the population) currently smoke [Jamal Morb Mortal Wkly Rep 63(47):1108-12, 2014] and up to half of these individuals will die prematurely because of their use of tobacco. Each year, millions of cigarette smokers require surgery and […]
Indications Surgery on the knee, calf, achilles tendon, foot, ankle. Post operatively for posterior knee pain following surgery Anatomical Landmarks Medial: Semitendinosus and Semimembranosus muscles Lateral: Long/Short head of Biceps Femoris Approaches There are many approaches to block the sciatic nerve. Using ultrasound, both the popliteal and subgluteal approach are common. Using nerve stimulator, lateral […]
Right ventricle is made up of trabeculae carneae but also contains the crista supraventricularis, which divides the inflow (from the atrium) and the outflow (to the PA). The crista is also attached to the anterior tricuspid valve, controlling it via the anterior papillary muscle (APM). Internal diameter is ~ 3.5 cm (as compared to 4.5 […]
Heal on their own within weeks, and generally require no treatment in and of themselves. The goal in managing these patients is to avoid pulmonary complications that are associated with the significant pain associated with these injuries, and in some cases, mechanical dysfunction (ex. flail chest). When not contraindicated, epidural anesthesia is perhaps the best […]
Using a transesophageal probe, right-sided anatomy is more difficult to visualize than left-sided anatomy, because the right ventricle is located anteriorly (further away, structures which attenuate sound are located in between the RV and the probe) and because the shape of the RV is geometrically more complex than the LV. Right Ventricle Preoperative RV function […]
Cardiac Risk for Cardiac Surgery Clinical Scoring Metrics Introduction While a multitude of risk-stratification scores have been developed, several risk factors have appeared recurrently – advanced age, female gender, elevated BMI, and decreased LV function are poor prognostic variables, as are emergent and redo operations [Kaplan JA, ed. Essentials of Cardiac Anesthesia. Saunders, 2008 p […]
Central to the preoperative assessment of thoracic anesthesia patients are two concepts: first is the idea that it is the thoracic surgeon, and not the anesthesiologist, who ultimately determines resectability (although the anesthesiologist may function as an important safety check. Furthermore, the anesthetic consultant may be asked to opine in certain intraoperative situations, ex. requirement […]
Heart failure is the inability of the heart to fill with or eject blood at a rate appropriate to meet tissue requirments.1 Acute or decompensated heart failure accounts for approximately 1million hospital admissions/year in the United States and is the leading cause for admission for adults older than 65. Heart failure can be classified based […]
Airway Resistance vs. Lung Compliance When pressure waveform slope increases, lung compliance has decreased. When the step-up (pressure at which flow begins) is elevated, airway resistance has increased. Alveoli are protected when resistance has increased (thus one can safely crank up the vent), whereas changes in compliance do not protect alveoli. Cardiac Performance Conditions associated […]
Background Acute kidney injury is the new name for Acute renal failure, defined as a Cr increase of 0.5 mg/dL if baseline < 2.5 mg/dL, a 50% decrease in GFR, or a 20% increase if baseline > 2.5 mg/dL. Anuria is defined as UOP < 100 mL/24h, and oliguria is defined as UOP 100-400 mL/24h. […]
The Relative Risk (RR) is used to compare the probability of an event between two different groups. It is simply the ratio of the probability of the event occurring in two, mutually exclusive groups: RR = π1 / π2 A RR of 1 means there is no difference in risk between the two groups. A […]
Classification and Triage Most lung injuries that require intervention will either need a chest tube, thoracotomy, or, rarely, a pneumonectomy. Management Options Chest Tube Pneumathoraces can usually be treated with a chest tube. Thoracotomy Thoracotomies are rare and generally only required if a) chest tube output exceeds 1500cc (usually due to injury of the internal […]
Primarily used as part of EMLA (1:1 prilocaine/lidocaine). Application of 0.5 – 1 g under an occlusive dressing can produce analgesia in 30-60 mins.
To roughly estimate the sample size of a population needed to find a statistically significant correlation between two variables (assuming r values ranging from 0 to 1.0, α = [0.01; 0.05] and β = [0.05; 0.1; 0.2]), consider using Figure 13-7 from Norman & Streiner: Biostatistics: The Bare Essentials, 3rd edition, p 141, BC Decker […]
A general equation to consider, assuming α = 0.05 and β = 0.20, and a one-sided test (see Crawley: Statistics: An Introduction Using R. John Wiley & Sons (West Sussex, UK), p. 9, 2005 [ISBN 0470022981]), is: n ≈ (8 x s^2)/δ^2 where s^2 is the variance of the response and δ represents the difference […]
Early Resuscitation: The Controversy Hypovolemic trauma patients will reliably respond to volume infusion with an increase in blood pressure, thus in the past ATLS recommended administration of 2L IVF as rapidly as possible. This recommendation has recently been questioned, as the downsides of dilutional anemia in the trauma setting (decreased O2 delivery, hypothermia, coagulopathies, and […]
Airway Note that with neck flexion, the ETT moves on average 3.8 cm in the adult (but can move as much as 6.4 cm) Anatomy relevant to the placement of a DLT: R mainstem is 2.5 cm in length. In 10% of adults, RUL departs in < 2.5 cm, and in 2-3% of adults, the […]
Power is defined as (1 – β) where β is the probability of a Type II error (see Type One and Type II Errors (Biostatistics Text)). It is the probability of detection a difference or probability of rejecting the Null Hypothesis (Biostatistics Text) (or H0) when you should. The interaction of α, β, and power […]
Paracervical Block Paracervical blocks are waning in popularity as they have been found to cause fetal bradycardia (which is associated with increased neonatal morbidity and mortality). Usually, paracervical block-induced bradycardia lasts < 15 minutes and is treated with lateral positioning and administration of oxygen. Regardless, paracervical blocks should be avoided in all patients with suspected […]
Because of the risk of aspiration remains elevated up to 6 week after delivery, neuraxial techniques are recommended. This requires a T5 sensory level. After 6 weeks, GA is thought safe.
Early Management of Acute Myocardial Injury Early Management of Acute Myocardial Injury (MONA? ONA may be better) Chest pain can sometimes be relieved by nitroglycerin (0.4 mg SL q5m x 3), but often cannot (esp. if patient was already taking nitrates). Also, never give nitro in patients with right heart infarction or who have taken […]
Intravenous Nutrient Solutions Dextrose usually makes up ~ 70% of the caloric intake, but as it is not a potent metabolic fuel it has to be hyperosmolar, and thus infused through large central veins. Amino acid solutions come in several varieties, but in general they contain ~ 50% essential amino acids and ~ 50% non-essential/semi-essential […]
Monitoring Physicians are notoriously unreliable at clinically detecting airflow obstruction [Am J Med 68: 11, 1980], thus we rely on objective measures. FEV1/FVC < 0.7 is indicative of obstructive disease but is difficult to obtain at the bedside. Peak expiratory flow rate ranges from 500 to 700 L/min in men and 380 – 500 L/min […]
Indications for One-Lung Ventilation Absolute Protective Isolation Massive Hemorrhage Infection Control of Ventilation Distribution Bronchopleural or bronchopleural cutaneous fistula Giant cyst or bullae (risk of rupture with PPV) Major bronchial disruption or trauma Unilateral Lung Lavage VATS Relative (Strong) – Surgical Exposure Thoracic aortic aneurysm Pneumonectomy Upper lobectomy Relative (Weak) – Surgical Exposure Esophageal surgery […]
The Paired t-Test examines repeated measurements obtained from the same set of individuals. The objective of the analysis is to show that any differences between two measurements of the same individuals are due to different treatment conditions. This approach is based on the theory that the same individuals will behave alike if they are treated […]
A Cochrane Database Review of cardiotocography (changes in the fetal heart rate and their temporal relationship to uterine contractions) found twelve randomised or quasi-randomised controlled trials including over 37,000 women, only two of which were high quality – compared to intermittent auscultation, continuous cardiotocography showed no significant difference in overall perinatal death rate (relative risk […]
Infection is the most common late complication of central venous cannulation, occuring in 5% of patients with central venous catheters (150,000 to 250,000 cases of catheter-related blood stream infection [CRBSI] per year). The overall mortality of patients with nosocomial bloodstream infections (not restricted to CRBSI) is ~ 35%, and the cost of one CRBSI can […]
Cardiac Rhythm Phase 0 (Rapid Upstroke) Massive sodium inflow. Activated by -65 mV threshold Phase 1 (Early Repolarization) K+ efflux and cessation of Na+ inflow Phase 2 (Plateau) Diminution of most current flows Phase 3 (Late Repolarization) Inactivation of Ca++ flows and re-activation of Ka+ efflux Phase 4 (Diastolic Depolarization) Cardiac Conduction SA node is […]
Electrocardiogram (ECG) Because patients having cardiac surgery are already known to have cardiac dysfunction, the purpose of an ECG is not to detect dysfunction, but rather to form a basis for comparison (i.e. to aid in the detection of intraoperative events) as well as to define the “ischemic threshold” (when used in the context of […]
Blunt cardiac injury is not well understood and probably relatively rare, although published incidences range from 8 to 76% [El-Chami MF et al. J Emerg Med 35: 127, 2008]. Because of its relative rarity, other cause of hypotension and/or arrhythmia should be ruled out before aggressively pursuing a diagnosis of cardiac contusion. EKG alone is […]
Bupivacaine is a local anesthetic drug. It belongs to the amide group of local anesthetics. Bupivacaine is on the WHO’s List of Essential Medicines. Trade names Marcaine, Marcain, Sensorcaine, Vivacaine Available concentrations 0.25%, 0.5%, 0.75% Chemical structure Bupivacaine Uses local infiltration peripheral nerve blocks spinal anesthesia epidural anesthesia and analgesia caudal block Mechanism of action […]
Stool Softeners Docusate (Colace) Mineral Oil – used post-MI and pregnancy, can lead to aspiration pneumonia Bulk-Forming Laxatives Psyllium (Metamucil) Polycarbophil (FiberCon) Osmotic Laxatives: can produce severe diarrhea if given excessively Magnesium Salts (MOM, MgCitrate) Polyethylene Glycol (GoLytely) Sodium Phosphate (Fleets) Lactulose (Cephulac) Stimulant Laxatives Senna (Senokot) Bisacodyl (Dulcolax) Phenolphthalein (Ex-Lax)
Right Ventricular Afterload The pulmonary artery contains alpha2 (and may contain alpha1) receptors [Troncy E et al. Br J Anaesth 79: 631, 1997; Blaise G et al. Anesthesiology 99: 1415, 2003] Left Ventricular Afterload Left ventricular afterload is most commonly defined as either left ventricular wall stress during systole (which, by Laplace’s law, is equal […]
One-Way Analysis of Variance (ANOVA) simultaneously compares the differences among sample means of more than two groups for a one-factor experiment. You may think of it as the t-test for more than two groups. H0: μ1 = μ2= μ3 (there is no difference between the three means) H1: μ1 ≠ μ2 ≠ μ3 (there is […]
Note that the guidelines on antibiotic prophylaxis have changed. Prophylaxis IS indicated in those with (valve patients highlighted): Guidelines for Antibiotic Prophylaxis in Valvular Disease [Wilson et. al. Circulation 116: 1736, 2007] Presence of a prosthetic cardiac valve or prosthetic material Previous infective endocarditis Unrepaired cyanotic congenital heart disease (including palliative shunts/conduits) Completely repaired congenital […]
Anterior mediastinal masses can obstruct the SVC, major airways, and even the heart. A series of 105 operations on patients with mediastinal masses showed that 3.8% had cardiorespiratory complications, and 11% had post-operative respiratory complications (7 of which were life-threatening, i.e. 6.67% overall) [Bechard P et al. Anesthesiology 100: 826, 2004]. Risk factors in this […]
“Normal” Presentation The majority (90%) of pregnancies are cephalic (either occiput anterior or occiput transverse). Breech Presentation Most are delivered by Cesarean section. Su et al. studied 2088 women from 121 hospitals in 26 countries (the Term Breech Trial) and showed that the relative risk for an adverse outcome of an elective Cesarean section is […]
This keyword has not yet been defined. Keyword history 95%/2013 See also ABA:Pregnancy – inhalation induction
Keyword history Percentage correct 96% Year asked 2013 See also ABA:Delayed transfusion reaction ABA:Transfusion rxn – Lab findings ABA:Febrile transfusion reaction
This keyword has not yet been defined. Keyword history 93%/2014 See also ABA:Sinus tachycardia – Mgmt ABA:Mgmt – WPW
This keyword has not yet been defined. Keyword history 98%/2014 See also ABA:Thyroid surgery – RLN monitoring ABA:Thyroidectomy – complications
This keyword has not yet been defined. Keyword history 42%/2014 See also ABA:Cardiac anatomy – TEE ABA:Cardiac vascular anatomy – TEE ABA:TEE views – perfusion distribution OpenAnesthesia.org:Course in Basic TEE
This keyword has not yet been defined. Keyword history 99%/2014 See also OpenAnesthesia.org:Course in Basic TEE
See the Keys to the Cart September 15, 2019 episode (link below). Keyword history 92%/2014 See also ABA:Coagulation changes in pregnancy Source Keys to the Cart: September 15, 2019
Definition The pharyngeal reflex, also known as the gag reflex, prevents unintentional foreign objects from entering the pharynx. However, studies show the role of the gag reflex and airway protection from aspiration is unclear at this time. Stimulus of the posterior tongue, soft palate, or posterior pharyngeal wall → sensory afferent nerve mainly via CN […]
Ambulatory ASA patients I – IV have a similar rate of postoperative complications in the outpatient setting, with the caveat being that the ASA III and IV patients should have stable disease. The types of procedures performed should also not entail significant fluid shifts, postoperative pain, or require postoperative hospitalization. Possibly poor candidates include those […]
This keyword has not yet been defined. Keyword history 84%/2014 See also ABA:O2 delivery vs. PaO2 ABA:Oxygen delivery – Factors impacting
Central line placement: Internal jugular vein Both the National Institute of Clinical Excellence and the CDC recommended ultrasound guidance for central venous line (CVL) placement for those who have training in using the technology. Using ultrasound guidance for CVL insertion in the internal jugular vein (IJV) has been shown to reduce the risk of mechanical […]
This keyword has not yet been defined. Keyword history 98%/2013 See also ABA:Metabolism – Meperidine ABA:MAO inhibitor – meperidine toxicity
This keyword has not yet been defined. Keyword history 81%/2013 See also ABA:One-lung ventilation – Indications
Keyword history Percentage correct 84% Year asked 2013 See also ABA:Cardiac arrest – Induced hypothermia ABA:Cerebral ischemia – deep hypothermia
This keyword has not yet been defined. Keyword history 85%/2014 See also ABA:Hepatic synthetic capacity – Dx
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Keyword history Percentage correct 91% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Etiol_bronchoconstriction&oldid=9461”
Keyword history Percentage correct 97% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Dx_-_Preeclampsia&oldid=9358”
Keyword history Percentage correct 76% Year asked 2013 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Effects_of_flumazenil&oldid=7928”
Keyword history Percentage correct 86% Year asked 2013 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Duchenne%27s_-_PFTs&oldid=7910”
Keyword history Percentage correct 99% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Dantrolene_mechanism&oldid=9368”
Keyword history Percentage correct 79% Year asked 2013 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Definition_-_Coma_vs_vegetative_state&oldid=7886”
Keyword history Percentage correct 94% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Decreased_CO_diffusion_-_Causes&oldid=9265”
Keyword history Percentage correct 88% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:DLT_vs._bronchial_blocker&oldid=9266”
Keyword history Percentage correct 60% Year asked 2014 See also ABA:Anemia compensation
Keyword history Percentage correct 82% Year asked 2014 See also ABA:Child-Pugh score – Factors Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Child-Pugh_Scoring_system&oldid=11054“
Keyword history Percentage correct 92% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Corticosteroids_-_Effect_on_lab_values&oldid=9242”
Keyword history Percentage correct 58% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Central_venous_pressure_wave_forms&oldid=9282”
Keyword history Percentage correct 84% Year asked 2013 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Causes_of_atrial_fibrillation&oldid=7830”
Keyword history Percentage correct 89% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Carotid_baroreflex_during_CEA&oldid=9227”
Keyword history Percentage correct 62% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from ” http://openanesthesia.wpengine.com/w/index.php?title=ABA:Caudal_anesthesia_-_Infant_dose& oldid=9689 /a>”
Keyword history Percentage correct 84% Year asked 2013 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Cardiac_PV_loops&oldid=7808”
Keyword history Percentage correct 35% Year asked 2014 See also ABA:Cardiac anatomy – TEE ABA:TEE views – perfusion distribution ABA:TEE – Ventricular wall anatomy Course in Basic TEE Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Cardiac_vascular_anatomy_-_TEE&oldid=9554“
Keyword history Percentage correct 76% Year asked 2013 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Cardiogenic_shock_-_DDx&oldid=7817”
Keyword history Percentage correct 93% Year asked 2014 See also ABA:CRPS I – Clin findings ABA:CRPS – diagnostic block Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:CRPS_type_1_-_Symptoms&oldid=9656”
• Diagnosis o History of exposure • Confirmation o Co-oximeter o Arterial or venous line samples • CO levels are elevated for days • Actual CO levels measured on arrival to the hospital correlates poorly with clinical status • Should not be used as sole criterion to determine need for treatment o CO levels on […]
Keyword history Percentage correct 98% Year asked 2013 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Benzocaine_%26_methemoglobinemia&oldid=7754”
PubMed Julie L Huffmyer, Edward C Nemergut Respiratory dysfunction and pulmonary disease in cirrhosis and other hepatic disorders. Respir Care: 2007, 52(8);1030-6 [PubMed:17650360] [WorldCat.org] (P p) Keyword history Percentage correct 61% Year asked 2014 See also ABA:Ascites – PFT’s
Keyword history Percentage correct 66% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Automated_drug_delivery_devices&oldid=9508”
Keyword history Percentage correct 8% Year asked 2013 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:B-blockers_-_Properties&oldid=7750”
Keyword history Percentage correct 87% Year asked 2013 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Autonomic_dysreflexia_symptoms&oldid=7742”
Keyword history Percentage correct 93% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Autonomic_dysreflexia_-_Risk_factors&oldid=9253”
Keyword history Percentage correct 85% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Arginine_vasopressin&oldid=9459”
Neostigmine, pyridostigmine, and edrophonium are primary excreted via both glomerular filtration and active tubular secretion. Neostigmine is water-soluble and roughly 50% of it undergoes renal excretion compared to 75% of pyridostigmine and edrophonium. Clearance of these drugs is significantly reduced in patients with ESRD and dosing adjustments may need to be made accordingly. When dosing […]
Keyword history Percentage correct 85% Year asked 2013 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Alveolar_gas_exchange&oldid=7690”
Keyword history Percentage correct 88% Year asked 2013 Suggest a change Suggest a change for this keyword
Keyword history Percentage correct 91% Year asked 2013 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:AS_and_arrhythmias&oldid=7663”
Keyword history Percentage correct 99% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:ACE_inhibitors_-_Side_effects&oldid=9271”
Keyword history Percentage correct 90% Year asked 2014 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:ASA_PS_Class_2_vs_3&oldid=9384”
Keyword history Percentage correct 83% Year asked 2013 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:AIMS_-_EMR&oldid=7658”
Keyword history Percentage correct 87% Year asked 2008 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Antithrombotic_drugs_-_duration&oldid=7720”
Keyword history Percentage correct 86% Year asked 2011 Suggest a change Suggest a change for this keyword Retrieved from “http://openanesthesia.wpengine.com/w/index.php?title=ABA:Antithrombotic_drugs_-_Preop_mgmt&oldid=7719”
Arterial blood gas (ABG) analysis provides important information about a patient’s overall acid-base status, as well as information about oxygenation and ventilation. Most ABGs typically provide some basic electrolyte concentrations. Co-oximetry measures concentrations of oxygenated hemoglobin (oxyHgb), deoxygenated hemoglobin (deoxyHgb or reduced Hgb), carboxyhemoglobin (COHgb), and methemoglobin (MetHgb) as a percentage of the total hemoglobin […]
Introduction/Background Normal minute ventilation is from 4-7 L/min. Normal deadspace ventilation makes up 30% of that. The shape of the oxygen/hemoglobin curve starts to flatten at SpO2 of 90% – for this reason, PaO2 is a poor indicator of oxygen content; however, the A-a gradient is an excellent indicator of gas exchange. PAO2 = FiO2 […]
Following the anhepatic phase of liver transplant, the graft is reperfused. The postreperfusion syndrome is a syndrome of severe hemodynamic compromise, arrhythmia, or asystole that occurs immediately after reperfusion. Definition: A decrease in systemic mean BP > 30% below baseline for at least 1 minute during the first 5 minutes of liver reperfusion. The estimated […]
Lateral Decubitus Position (Awake, Spontaneous, Closed Chest) Simply moving into the lateral position has several, important effects – first, the hydrostatic gradient moves 90 degrees (occurring laterally), but because the lungs are taller than they are wide, ΔP is smaller and there is relatively less Zone 1 (PA > Pa > Pv). Second, because abdominal […]
Neurologic Complications Pain Control Pain control is an essential component of post-operative recovery [Kavanagh BP et al. Anesthesiology 81: 737, 1994]. The most difficult to treat may be shoulder pain, which affects 80% of patients and may be due to diaphragmatic irritation (transmitted via the phrenic nerve). Preemptive Analgesia There is some evidence that preemptive […]
Oxygen Therapy When is O2 Therapy Needed? Currently, the “standard” indication for supplemental oxygen therapy is a PaO2 < 60 mm Hg or a SaO2 of < 90% [Resp Care 47: 717, 2002], however arterial oxygen may be as low as 40 mm Hg in supine patients without producing hyperlactemia – this has been shown […]
Pressure & Flow Modern CPB machines pump blood into the arterial system using a centrifugal pump. The flow of a centrifugal pump increases as its angular velocity (RPMs) increases. Pressures are therefore a function of the set flow rate and the resistance to flow, and can thus be modified by changing either the flow rates […]
Patients are more likely to accept a peripheral if they are assured that sedation can be administered. Considerations/relative contraindications include skin infection, coagulopathy, or preexisting neuropathy Preparation for Peripheral Blocks Should be evaluated medically exactly the same way as a patient undergoing general anesthesia. IV catheter must be in place, and the OR must be […]
Ultimately, all trauma leads to decreased organ perfusion, cellular ischemia, and a cascade of edema and inflammation. Once begun, inflammation becomes a disease process independent of its origin, and can lead to multiple organ failure and death even after a patient has been completely resuscitated. The CNS response to trauma is predominantly neuroendocrine in nature, […]
Incidence and Definitions Occurs in ~ 10% of pregnancies and is a major cause of maternal mortality. PIH includes gestational hypertension, preeclampsia, and eclampsia (preeclampsia + seizures). Characterized by BP > 140/90, and proteinuria (> 0.3 g/day). An associated condition is HELLP syndrome (hemolysis, elevated liver enzymes, low platelets). Death, if it occurs, is due […]
Controversy: whether or not intraoperative opiates are indicated when general anesthesia can be maintained by other means (volatile anesthetics, propofol, lidocaine, ketamine, dexmedetomidine, etc.). On one hand, opiates clearly have MAC-reducing effects. On the other hand, one could argue that analgesics are unnecessary during general anesthesia as these patients should have no awareness or memory. […]
Preoperative Evaluation and Questions: Which extremities are involved? Open? Closed? Where is the IV access? If one or both upper extremities are involved IV access could be an issue. Starting Hct? NPO status? Compartment syndrome? Myoglobinuria/HyperKalemia? Open fractures are “urgent” and should be taken to the OR within 1-4hrs of arrival for wash-out/reduction/fixation of Fx. […]
Brain Incidence of adverse neurologic / psychiatric disturbances following CPB is approximately 6% [Roach GW et al. N Engl J Med 335: 1857, 1996], although there is some data to suggest that over the long term the incidence is no different than in patients treated non-surgically, but is rather a function of the natural history […]
Daily Energy Expenditure The Harris-Benedict equations were published in 1919 and did not take into account changes in body weight caused by obesity or edema, thus ideal body weight must be used. The equation BEE (kcal/day) = 25 x wt. (kg), or 1 kcal/kg per hour is an approximation of the H-B equations but has […]
“The Null Hypothesis (abbreviated H0) states that population parameters are equal (or equal to s specific value). There is NO difference between the parameters being studied. The Alternative Hypothesis (abbreviated H1) states that the population parameters are unequal (or NOT equal to a specific value). In other words, a difference exists between the parameters being […]
As many as 2% of pregnant women undergo anesthesia for non-obstetric surgery [Rosen MA. Anesthesiology 91: 1159, 1999]. Routine pregnancy testing should be mandatory for all women of child-bearing age. Note that organogenesis occurs from 15-56 days of gestation. Early concerns for the pregnant patient revolve around the potential for altered organogenesis, but as the […]
SELENIUM AND RENAL FAILURE Selenium and Renal Failure (reduces ARF but no change in mortality) Anstwurm MWA, Schottdorf J, Schopohl J, et al. Selenium replacement in patients with severe inflammatory response syndrome improves clinical outcome [Crit Care Med 27: 1807, 1999]. [Transplantation 2005;80: 1363–1368]
Antioxidants Joint guidelines published by Society of Critical Care Medicine (SCCM) [Martindale RG et al: Crit Care Med 37: 1757, 2009] and American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) state “Immune-modulating enteral formulations (supplemented with agents such as arginine, glutamine, nucleic acid, ω-3 fatty acids, and antioxidants) should be used for the appropriate patient […]
Apgar Scores and Resuscitation Guidance Apgar > 8: suction, warm Apgar 5-7: O2 by mask (mechanically vent if needed), external stimulation Apgar 3-6: mechanical ventilation by mask, intubation if spontaneous ventilation absent, ABG from double-clamped cord Apgar < 2: intubation, chest compression if HR < 60 For neonates with an Apgar or 0-4, have a […]
Mechanism of Action Converted to NO which stimulates cGMP production. Acts as a smooth muscle relaxant and venodilator (why NTG is more of a venodilator than a vasodilator is not known). Note that the process of NO formation is dependent on availability of sulfhydryl (SH) groups and thus tolerance can develop. Hemodynamic Effects Systemic Venodilation […]
Preoperative Considerations Sedation Avoid sedatives and/or opiates if elevated ICP is a concern (decreased RR leading to elevated ICP, obscuration of neurologic exam – for every 1 mm Hg decrease in pCO2, CBF decreases by 1-2 mL/100g/min). Electrolytes Most of these patients are at high risk for electrolyte abnormalities (mental status changes, steroids, diuretics, contrast […]
Data Brief Report: [Gourlay GK et al. Br Med J (Clin Res Ed) 284: 630, 1982; FREE Full-text at PubMed Central] Pharmacodynamics of methadone in human post-surgical patients: [Gourlay GK et al. Anesthesiology 57: 458, 1982; FREE Full-text at Anesthesiology] Effect of supplemental doses of methadone: [Gourlay GK et al. Anesthesiology 61: 19, 1984; FREE […]
Volatile Anesthetics Both IV (with the exception of ketamine) and volatile anesthetics reduce CMRO2, however with IV anesthetics there is a concomitant reduction in CBF. Volatile anesthetics, which are vasodilators, do not reduce CBF. In fact, they raise it. Sevoflurane Desflurane Isoflurane N2O CBF + + + + + + CPP – – – – […]
Sympathetic Nervous System Afferent SNS Efferent SNS SNS fibers, which originate in the thoracic spine, pass through the stellate ganglion and cervical sympathetic trunks prior to forming the cervical cardiac nerves, which often unite to form one large nerve that eventually parallels the left main. Other thoracic sympathetics unite to form the thoracic cardiac nerves. […]
EEG EEG changes generally occur when CBF decreases to 20cc/100g/min [except under isoflurane, where CBF can fall to 8-10cc/100g/min]. Normal brain perfusion is approximately 50 cc/100g/min, and cellular damage occurs at 12cc/100g/min, thus EEG can theoretically warn of impending perfusion deficits. That said, the EEG is a global measure and can be affected by a […]
Orthopedic Trauma Classification and Triage Musculoskeletal trauma patient can be roughly classified into three types: 1) isolated, closed injuries that require surgical intervention can be done on an elective basis, and trauma team involvement is optional; 2) multiple fractures of major long bones and/or joints, which requires trauma team resuscitation / exclusion of life-threatening injuries, […]
Moyamoya disease is a form of occlusive cerebrovascular disease. Patients develop progressive occlusion of the internal cerebral arteries at the skull base. The disease is idiopathic in most cases. The internal cerebral arteries are often asymmetrically affected. Patients are at risk for both hemorrhagic and ischemic stroke. On cerebral angiography, in more advanced stages of […]
Pre-hospital assessment Knowledge of the patient’s pre-hospital state is important, as any signs of deterioration suggest an ongoing insult (such as a mass lesion) which may be amenable to surgical therapy. Vital Signs Temperature below 32.2C (90F) can significantly alter the neurologic exam. Alcohol, drug intoxication, post-operative state are the most common causes. Complications of […]
Supply The heart normally receives 4% of cardiac output, or ~ 250 mL/min of blood. Fatty acids and lactate are the predominant sources of energy, although glucose can be utilized (depending on glucose and insulin concentrations, as well as PaO2). Demand Impact of PVA on mVO2 (Image by Thiele, Nemergut, Lynch)Normal mVO2 is 8-10 mL/100g/min. […]
Overview of Mitral Prolapse Incidence Traditionally it was thought that MVP occurred in ~ 5% of the general population, however an offshoot of the Framingham study, which examined over 1800 echocardiograms, placed the incidence at 2.4% and noted that the difference in men and women was significant (59% of them occurred in women) [Freed LA […]
Overview of Mitral Stenosis Etiology Almost always due to rheumatic disease, normally becomes symptomatic ~ 20 years after the infectious insult, although acute increases in DO2 requirements (ex. pregnancy, sepsis) can result in earlier onset of symptoms. > 50% of patients will have another, coexisting valvular pathology (most commonly mitral regurgitation, but 25% will have […]
Overview of Mitral Regurgitation Etiology Can be caused by rheumatic fever (usually associated with mitral stenosis), dilated cardiomyopathy, LV dilation from chronic ischemic heart disease, papillary muscle dysfunction or chordae tendineae rupture. Etiology is a major determinant of outcome in cardiac surgical patients. Medical and Surgical Treatment Medical treatment may include digoxin, diuretics, and/or vasodilators—including […]
Intraarterial Catheterization Most practitioners routinely place an intraarterial catheter in thoracic surgery. For mediastinoscopic exams, a right-sided catheter will help monitor for brachiocephalic artery compression (but has the disadvantage of not working as well when this occurs); a left-sided catheter functions continuously, but if placed a right-sided pulse oximetry probe should be placed, as it […]
Pancuronium (Pavulon): relatively long acting, can accumulate if given continuously (often given in intermittent doses), has a vagolytic effect, and must be reduced in renal failure. If hepatic and renal function are intact, may be the preferred agent in the ICU [Crit Care Med 30: 142, 2002; Crit Care Med 32: S554, 2004] Rocuronium (Zemuron): […]
Central Nervous System Processed EEG (BIS) Cerebral Oximetry Cerebral desaturations appear to be related to neurological outcome, with cumulative area of rSO2 < 40% being the most significant predictor for postoperative impairments [Yao FS et al. J Cardiothorac Vasc Anesth 18: 552, 2004]. Whether or not they change management is controversial. Murkin JM et al. […]
The range, the variance, and the standard deviation are the most common measures of spread or variation. The range is the length of the smallest interval which contains all the data. It is calculated by subtracting the smallest observation (sample minimum) from the greatest (sample maximum). Alternatively, the range can articulated as simply listing the […]
Left Ventricular Failure Heart failure is the inability of the heart to fill with or eject blood at a rate appropriate to meet tissue requirments.1 Acute or decompensated heart failure accounts for approximately 1 million hospital admissions/year in the United States and is the leading cause for admission for adults older than 65. Heart failure […]
Background: Autosomal dominant (90% have a mutation in the Fibrillin-1 gene, most others have a mutation in transforming growth factor receptor-2 gene) connective tissue disorder with an incidence of approximately 1 in 4,000. A similar, but less common variant known as Loeys-Dietz aneurysm syndrome (LDAS) is due to a mutation in the transforming growth factor […]
Substance abuse is common in women of childbearing age. Cocaine abuse is the most harmful, and can lead to IUGR, premature labor, uterine-placental insufficiency, or abruption. The mother may be tachycardic, hypertensive, or euphoric, and is at risk for MI, arrhythmias (potentially lethal), pulmonary edema, seizures, SAH. In treating parturients on cocaine, avoid pure beta-blockers […]
Interleukin-6 Plasma IL-6 concentrations have been directly correlated with risk of death in intra-abdominal sepsis, and measurements of this single variable predicted outcome in these cases with remarkable (82.9%) accuracy [Br J Surg 81: 1306, 1994]. Plasma IL-6 concentrations have been found to be 69% (95% confidence interval 30–108%) higher in nonsurvivors compared with survivors […]
Heart disease may be present in as many as 4% of parturients, and a mortality rate as high as 6.8% in NYHA class III-IV patients. NYHA class I-II patients (asymptomatic, or slight activity limitations), by contrast, have a mortality rate < 1%. The most dangerous abnormality is pulmonary hypertension, followed by mitral stenosis combined with […]
The Mean, the Median, and the Mode are the most common measures of central tendency. The mean (most properly called the arithmetic mean) is the simple average of the data: the sum of all data points divided by the number of data points. The median is described as the numeric value separating the higher half […]
Uterotonics Oxytocin Whereas true oxytocin, which is similar to vasopressin, causes hypertension, synthetic oxytocin (Pitocin) causes hypotension and should be given slowly (ideally ~ 40U in at least 500 cc crystalloid over 10 mins). A bolus of 10U synthetic oxytocin was shown to lower MAP 40%, and SVR 59% (thus cardiac output actually increased), an […]
Left ventricle is 4.5 cm across internally. At 8-15 mm thick, it is both thicker and larger than the RV. Systole The most basic measure of systolic function is cardiac output, which is usually indexed to body surface area (normal cardiac index [CI] is 2.5 to 3.5 L/min/m2). During high-stress situations CO can increase to […]
MAC Reduction Systemic local anesthetics reduce MAC of volatile anesthetics in rats by approximately 40% [DiFazio CA et al. Anesth Analg 55: 818, 1976], and in cats by as much as 59% [Pypendop BH et al. Anesth Analg 100: 97, 2005] FREE Full-text at Anesthesia & Analgesia. Wilson’s study of IV lidocaine (50-200 ucg/kg/min) […]
Criticisms of Current Recommenations “The current recommendations regarding maximum doses of local anesthetics presented in textbooks, or by the responsible pharmaceutical companies, are not evidence based (ie, determined by randomized and controlled studies). Rather, decisions on recommending certain maximum local anesthetic doses have been made in part by extrapolations from animal experiments, clinical experiences from […]
Management of Bradycardia in the OR1 Bradycardia can be defined as a heart rate <60 b.p.m. and/or a rapidly falling heart rate. It is not uncommon for adults under general anesthesia to have a heart rate between 40 and 60 bpm, and may vary secondary to home medications (ie: Beta blockers). Therefore it must be […]
Tachycardia is defined as a heart rate greater than 100bpm. Tachycardia in the OR is not uncommon, and generally associated with severe hypovolemia, an inflammatory response or an inadequate anesthetic for surgical stimulus. The differential diagnosis for tachycardia in the OR is similar to that of bradycardia, including the 8H’s and 8T’s. Evolution of tachycardia […]
The Mann-Whitney Test is a non-parametric test that compares the population means between two independent groups. If a data fails a “test for normality” (i.e., W-test or the Kolmogorov-Smirnov test) you cannot use the t-test and must use the Mann-Whitney Test. The Mann-Whitney Test is also known as the U-test, the Mann-Whitney U Test, or […]
Consider advocating controlled hypotension more strongly than in patients who will accept blood products. Take particular care not to order laboratory tests which require phlebotomy but which will not change management. It is difficult to make broad recommendations on the treatment of Jehovah’s Witness patients, as most (but not all) case series are relatively small, […]
Simply put, the purpose of cardiopulmonary bypass (CPB) is to provide the cardiac or thoracic surgeon a surgical field that would otherwise be incompatible with life (or, at the very least, would incur unacceptable morbidity). More specifically, the goals of CPB are to 1) move volume (blood) 2) add oxygen to blood 3) remove CO2 […]
While 87% of lung cancer patients die of their disease, 13% survive, representing 26,000 patients per year in North America alone (almost all attributable to surgery). Thus, while the overall mortality of thoracic surgery is 3-4% [Licker M et al. Ann Thorac Surg 81: 1830, 2006], because it is impossible to tell a priori who […]
Trauma is the leading cause of years of life lost before the age of 75 years. Interestingly, while many European EDs are directed by an anesthesiologist with an interest in trauma, in the United States very few anesthesiologists specialize in trauma. To attain level one status, a trauma center must have an available OR and […]
50% nitrous oxide will provide satisfactory analgesia in some women undergoing vaginal delivery, and is insufficient to cause respiratory depression or significantly impair airway reflexes [Stoelting RK. Basics of Anesthesia, 5th ed. Elsevier (China) p. 489, 2007]. A Chinese study (only English abstract is available) of 1300 women comparing 50% nitrous oxide to oxygen showed […]
The original guidelines for ACLS were issued in 1974 by the America Heart Association. The course was designed for health care providers who could provide advanced intervention over the traditional basic life support. Over the past several years there has been developing interest in an anesthesia centric version of the ACLS guidelines. ASA-ACLS takes from […]
The perils of giving critically-ill patients arbitrary amounts of fluid without advanced monitoring (see section on modern fluid management below) was recently hilighted by the FEAST Trial, which included 3141 febrile pediatric patients with impaired perfusion (defined as capillary refill > 3 seconds, a lower-limb temperature gradient, “weak” radial-pulse volume, or severe tachycardia [defined based […]
History The first percutaneous transluminal coronary angioplasty was performed in 1977, by Dr. Andreas Gruentzig. This marked the birth of interventional cardiology, although catheter-based alternatives to valvuloplasties had been explored (unsuccessfully) since the 1960s. The first successful percutaneous mitral (1982) and aortic valvuloplasties were performed in the 1980’s, although these procedures did not achieve widespread […]
The three most common (and rational) indications for mechanical ventilation are 1) inadequate oxygenation 2) inadequate ventilation 3) inability to protect the airway. Red Flags for Pending Intubation General Cause for Concern (red flags for pending intubation@): RR > 25/min PCO2 > 50 mm Hg PO2 < 50 mm Hg SpO2 < 90% Always take […]
Vomiting is a very important sign regarding intraparenchymal hemorrhage – almost 50% will vomit as opposed to only 2% of patients with ICA, MCA, or ACA ischemia [Neurology 28: 754, 1978]. Rebleeding is common in IPH patients, and is most likely within 6-24 hours. For this reason, blood pressure should be controlled rigidly – always […]
Induction Ketamine deserves stronger consideration as it is a known bronchodilator. Consider IV lidocaine 1-1.5 mg/kg prior to airway manipulation. Maintenance Strongly consider volatile anesthetics, as all of them decrease airway reactivity and bronchoconstriction (sevoflurane the most [Rooke GA et al. Anesthesiology 86: 1294, 1997]), and the vast majority of thoracic surgery patients have some […]
Organ Rejection T-cell Biology Immunosuppressants are all designed to inhibit T-cell activation, a two-part process consisting of the sensitization and effector stages. The sensitization stage involves an interaction between antigen presenting cells (APC, e.g. dendritic cells, which load their antigens onto the MHC molecules for display) and host T-cells. The effector stage involves stimulation by […]
Priming Solution The optimal fluid for priming the cardiopulmonary bypass machine is not known. Most priming solutions in adults are blood-free, as the drop in hematocrit allows substantial decreases in temperature without adversely affecting blood viscosity. Albumin has the advantage of increasing colloid oncotic pressure while at the same time attenuating the platelet-lowering effects of […]
The normal brain weighs 1400 g and contains 75 cc of CSF and 75 cc of blood. The cranium can absorb an additional 100-150 cc fluid before ICP begins to rise – this ability to conform increases as patients age (volume may shrink as much as 30%). CSF is produced at 400-500 cc/day. Unlike most […]
Surgical procedures should obey the following hierarchy: Airway (cricothyroidotomy) Exsanguination (ex. pelvic angiography, laparotomy, thoracotomy) Intracranial mass removal Eyesight, sepsis (debridement), and hemorrhage control Moblization (ortho) Cosmesis (plastics)
Skin Hygiene Commonly Used Antiseptic Agents Alcohol Iodophor Chlorhexidine Advantage Broad Spectrum; Superior reduction in bacterial counts; Rapid Onset Broad Spectrum Residual activity ~ 6 hrs Disadvantage Little residual activity; Water-based solutions can irritate skin Slow onset; Can irritate skin Narrow spectrum In all, the following recommendations should be observed – use antiseptic solutions to […]
Introduction Often hereditary (underlying pathophysiology is an excess of calcium channels), hypertrophic cardiomyopathy leads to decreased LVEDV secondary to the hypertrophic heart (stroke volume, by contrast, remains normal). Furthermore, during contraction the IV septum and anterior mitral leaflet may approach each other, and if the LVOT is narrow enough Venturi forces will pull the valve […]
HIV Patients P.carinii used to be the most common cause of pneumonia in HIV patients, however now it is bacterial pneumonia [Chest 120: 1888, 2001]. CMV, mycobacterium, and MAI can also cause pneumonia in this population. Most common isolates are encapsulated organisms – S. pneumoniae, H. influenza (100x the normal rate), and S. aureus [Chest […]
Aspergillus Previously amphotericin B was considered the first line treatment for aspergillus, however due to its side effect profile alternative agents have been sought. Recent data suggest that for the prevention of invasive fungal infections in at risk patients, voriconazole (a triazole) may be as efficacious (although it should be noted that in the Walsh […]
Introduction Data supporting a strong association between hyperglycemia and poor outcomes are abundant, and include patients with myocardial infarction {10338454,12446057,10711923}, traumatic injuries (Yendamuri Journal of Trauma 2003;55(1):33, Sperry Journal of Trauma 2007;63(3):487), and postoperative wound infections (Estrada Annals of Thoracic Surgery 2003;75(5):1392, Guvener Endocrine Journal 2002;49(5):531, Latham Inf Control & Hosp Epidem 2001;22(10):607, Golden Diabetes […]
OpenAnesthesia.org is divided into several, major Units (ex. Anesthesia Text, Critical Care Manual, Pharmacology…), each of which is subdivided into Chapters (or in some cases, even smaller subdivisions, such as sections, individual key words, topics, points of interest, or bibliographic references). This page contains all of the Chapters for the Guide to Surgical Procedures. The […]
Physiology Afterload is determined by impedance, which is a combination of resistance and compliance. Thus, arterial blood flow, which is pulsatile, is not simply a function of contractility and resistance. In fact, compliance may play a significant role in blood flow, so much that some recommend abandoning the use of SVR as a clinical measure […]
Zone II injuries (from the clavicle to the angle mandible) are usually operated on emergently, otherwise most repairs of head/neck/ENT trauma can be accomplished on an urgent (but not emergent) basis. Many surgeons will request nasotracheal intubation; however, if this cannot be accomplished safely, it is reasonable for them to either work around an orotracheal […]
Impact of CHF on Anesthetic Risk Known CHF is associated with an increased risk of surgical mortality [Stoelting p. 382, 2006]. In fact, in the Revised Cardiac Index validation set (1422 patients), CHF (diagnosed by chest X-ray in combination with clinical suspicion) had the highest OR for major cardiac complications (OR 4.3) [Hernandez et al. […]
Hematology Transfusion Criteria A study of 838 critically ill, euvolemic ICU patients showed that there were no differences in 30 or 60-day mortality when treated by restrictive (hemoglobin 7.0 – 9.0 g/dL) or liberal (hemoglobin 10.0 – 12.0) transfusion criteria. The only statistically significant differences were 30-day mortality in patients with an APACHE score < […]
Introduction to Hemostatis Coagulation is now thought to be a cell-based process occurring on the surface of endothelial/subendothelial cells and platelets, rather than the two-pathway plasma-based process traditionally described [Roberts et. al. Anesthesiology 100: 722, 2004; Schenone et. al. Curr Op Hematol 11: 272, 2004]. Native anticoagulants include heparin sulfate proteoglycans (increase antithrombin and thrombomodulin […]
Crystalloids Normal saline can cause a hyperchloremic metabolic acidosis, whereas lactated ringer’s can cause a metabolic alkalosis secondary to metabolism of lactate (which produces bicarbonate). Never use LR with blood products as the calcium will bind to the citrate. Dextrose-containing solutions should be avoided in patients with neurologic injuries as they may cause hyperglycemia, cerebral […]
Fisher’s Exact Test is used to determine whether there is a difference in the population proportions between two small groups. The definition of “small” is variably defined. Many users would define small as when the total number of patients is each group is less than 30 or when the absolute number of successes in each […]
Indications Surgery on the anterior aspect of the thigh or superficial operations on the medial lower leg (saphenous nerve), as well as post-operative pain control for femur and knee surgery (knee arthroscopy requires addition of local anesthetic to the arthroscopy site). When combined with a sciatic block, a femoral nerve block can nearly completely anesthetize […]
Preparation When discontinuation of CPB is imminent, the anesthesia provider should prepare for a safe and efficient transition to the native circulation so that full attention can be devoted to the patient during this critical period. One should attempt to anticipate potential adverse events, however to a certain extent this is not possible, hence the […]
Early (< 48h) vs Late (>= 8 d) Parenteral Nutrition in Critically-Ill Patients (June 2011) Prior data on early vs. late feeding in critically ill patients have been difficult to interpret. A metaanalysis of 15 studies examining early enteral nutrition (containing 753 subjects) suggested that early enteral nutrition was associated with a significantly lower incidence […]
Controversy: whether or not droperidol should be used as an antiemetic agent Data In Favor of Black Box Warning: FDA black box warning Review of Documented Cases: Habib et. al. The FDA warning is based on 10 reported cases from 1997-2002 [Habib et. al. Anesth Analg 96: 1377, 2003; FREE Full-text at Anesthesia & Analgesia] […]
Background: occurs in >8% of U.S. population. Diagnosed by a fasting glucose > 126 (mg/dL), two random glucoses > 200, or a oral glucose tolerance test (75g) leading to a blood glucose > 200 at two hours post. Clinical manifestations include polyuria, polydipsia, and polyphagia. Type 1 DM (prevalence 0.4%) is caused by pancreatic islet […]
Pertinent Anatomy The epidural space is a potential space. The average distance to the epidural space is ~ 5 cm [Segal S et al. Reg Anesth 21: 451, 1996], but the range is up to 3-9 cm. The epidural space contains Batson’s venous plexus, which is dilated during pregnancy and thus more susceptible to needle […]
In order to obtain a fetal EKG, a presenting fetal part must be available for lead placement. Normal HR is 120-160 with 5-25 beats/min of beat-to-beat variability. Note that maternal opiates, atropine, or anesthetic agents can reduce beat-to-beat variability. Two types of decelerations are problematic – late (starting 10-30 seconds after contraction onset), which represent […]
Depressed Consciousness Consciousness has two components – arousal and awareness. Awake patients are aroused and aware. Somnolent patients are easily aroused and aware. Stuporous patients are aroused with difficulty and have impaired awareness. Comatose patients are unarousable and unaware. Those in a vegetative state are aroused (ie awake, eyes open) but unaware. Common etiologies include […]
Low Tidal Volumes Parameter Lung-Protective Strategy Traditional Strategy Inflation Volume 5 – 10 mL/kg 10 – 15 mL/kg Mechanical Sighs none 15 – 30 mL/kg at 6 – 12/hr End-Inspiratory Peak Pressure Plateau < 35 cm H2O Peak < 50 cm H2O PEEP 5 – 15 cm H2O Only when needed to keep FiO2 < […]
Introduction Essential hypertension is defined as 160/90 with no other obvious cause. Note that these patients are at increased risk for CAD as well as PVD. Importantly, a large percentage of patients with significant PVD will have 50% stenosis in at least one coronary artery – a study of 1000 patients who underwent elective peripheral […]
Mechanism of Action/Pharmacology Reduced rate of Phase 4 (precedes the sharp upstroke in Phase 0) depolarization Has a methylester group and is hydrolyzed by red cell esterases (half-life 9 minutes) Hemodynamic Effects Decreases heart rate, contractility, and sometimes blood pressure. Note that beta blockers do not always decrease blood pressure, especially during acute administration, although […]
(based on the Sepsis Guidelines) (Level III) Appropriate cultures should be obtained before antimicrobial therapy is initiated, although one should not delay antibiotic administration unnecessarily in order to wait for cultures (i.e. get the cultures quickly) – at least two blood cultures should be obtained with at least one drawn percutaneously and one drawn through […]
Definition An epidural hematoma is defined as symptomatic bleeding within the spinal neuraxis. Pathogenesis The pathogenesis is still unknown although many theories exist, including epidural venous bleeding, epidural arterial bleeding, and bleeding from vascular malformations, Risk Factors Coagulopathies, traumatic needle insertion during placement of an epidural catheter or performance of a spinal anesthetic and spontaneous […]
Practically speaking, data can be divided into categorical variables and numerical variables. The type of variables you measure determines the type of statistical analysis that is appropriate Categorical Variables Categorical variables are selected from established categories. Of note, the categories must be clearly defined. Examples include gender (male vs. female), pregnancy (pregnant vs. not pregnant) […]
Preoperative Evaluation and Questions: What is the indication for surgery? (Aneurysm, AVM, SAH, Tumor, Chiari) Pre-op Neurologic condition? Any deficits? Need for Neuromonitoring? Hunt-Hess Grade for Aneurysm? (I-V) Risk: Mortality is based on Hunt-Hess grade: I =2%, II =5%, III =15-20%, IV =30-40%, V =50-80%. Morbidity: Hydrocephalus 15-20%, Neurogenic pulmonary edema (most common cause of […]
General Considerations Avoid extreme or prolonged changes in both heart rate and blood pressure [Slogoff et. al. Anesthesiology 68: 676, 1988]. The traditional recommendation is to maintain SBP within 20% of awake values. That said, ~ 50% of perioperative ischemic episodes are not preceded by premonitory changes in heart rate or blood pressure, thus justifying […]
Anatomy Left Coronary Artery Left coronary splits into the LAD (represented by V3-5 on the EKG, supplies the interventricular groove via diagonal and septal perforator branches) and the circumflex (follows the AV groove, giving off the obtuse marginal and supplying the posterior LV as well as some of the RV, represented by lead I and […]
Defined as RVH (and subsequent ventricular dysfunction) secondary to chronic pulmonary hypertension. The key to management in these patients is to avoid increasing PVR (precipitants include hypoxemia, hypercarbia, acidosis, nitrous oxide [Hilgenberg JC et al. Anesth Analg 59: 323, 1980]). In severe cases, beta-agonists may be required to overcome PVH, but with the concomitant risk […]
Related Podcast Ask the Experts on perioperative hemostatis with Dr. Jerrold J. Levy, January 2010 Antifibrinolytics Aminocaproic Acid Most studies validating aminocaproic acid (EACA) use a bolus + infusion technique, including a 15 g bolus followed by infusion of 1 g/h [Hardy JF et al. Ann Thorac Surg 65: 371, 1998], a bolus of […]
Contraindications Absolute Contraindications to Neuraxial Analgesia patient refusal infection at insertion site coagulopathy hypovolemic shock Hypotension is the most common complication and can be avoided/attenuated with hydration and positioning (left-ward placement of uterus, avoid supine position) [Stoelting RK. Basics of Anesthesia, 5th ed. Elsevier (China) p. 488, 2007]. Excessive level of anesthesia may occur, and […]
The Chi-Square (χ2) test for categorical variables determines whether there is a difference in the population proportions between two or more groups. H0: π1 = π2 = π3 (there is no difference between the three portions) H1: π1 ≠ π2 ≠ π3 (there is a difference between the three portions) Example: You might use the […]
Cerebral Blood Flow and Autoregulation Mannitol, albumin, and in particular dextran [Neurosurgery 11: 739, 1982; Neurology 34: 24, 1984] all help prevent RBC aggregation and can improve blood flow. Effects of Cerebral Perfusion Pressure CBF is maintained at a constant rate as long as MAPs range from 60 – 160 mm Hg [Doberstein in Youmans’ […]
The Inflammatory Response SIRS, MODS, and Related Phenomena Infection and inflammation are not the same thing, and failure to recognize this can lead to errors in management [Chest 101: 1644, 1992] SIRS requires two or more of the following symptoms [Chest 101: 1644, 1992] and can be caused by infection, trauma, shock, ischemia, pancreatitis, intestinal […]
Introduction to Ventricular Assist Devices The impetus for development of ventricular assist devices is the rapidly increasing number of patients with heart failure (5.3 million in the United States alone) combined with the unavailability of organs for transplantation (~ 2,200 per year in the U.S.) and the utter inadequacy of medical therapy. In fact, medical […]
Transversus Abdominis Plane block is technique of regional anesthesia where the drug is injected in the plane between the Transversus Abdominis and Internal Oblique muscles.The site of injection is Lumbar Trangle of Petit which is bounded by Lattissmus Dorsi, External Oblique and superior border of Iliac Crest. Around 20 ml of drug deposited in the […]
Ischemic Penumbra and Ischemic Thresholds Cortical potentials cease at 16-18 mL/100g/min, cell structure fails at 8-23 mL/100g/min. This also depends on duration – CBF of 18-23 mL/100g/min can be tolerated for two weeks, whereas 10-12 mL/100g/min can only be tolerated for 3 hours, and 8 mL/100g/min for one hour before neuronal death occurs [Acta Neurochir […]
Nosocomial Pneumonia Diagnosis is difficult, as 40 – 50% of ICU patients with fever and new onset pulmonary infiltrates do not have pneumonia [Chest 101: 1005, 1992; Chest 106: 221, 1994]. Note that nosocomial pneumonias are often polymicrobial, thus the values in the table below exceed 100%. Microbial Origin of Pneumonia Microbial Origin of Pneumonia […]
Hypoxic pulmonary vasoconstriction was originally described in 1946, by Von Euler and Liljestrand – they were studying the effects of hypoxic gas mixtures, and found that PA pressures increased with 10.5% inspired O2 [Von Euler and Liljestrand. Acta Physiol Scand 12: 301, 1946]. Since then, HPV has been well-described in multiple mammalian models, including humans. […]
Nervous System Gin and Chan showed that the median MAC of isoflurane in humans fell 28% during pregnancy (1.075% to 0.775%, p < 0.02) based on Dixon’s up-down method in 20 women (10 per group) [Gin T and Chan MT. Anesthesiology 81: 829, 1994]. They subsequently showed that the MAC of enflurane decreased from 1.65% […]
Introduction The following is intended to provide a brief introduction to the world of pacemakers and automated implantable cardioverter defibrillators (AICDs). While the information below may be of use and is hopefully applicable, nothing that follows should trump, supercede, or replace manufacturer recommendations regarding specific devices, which should ALWAYS be consulted, when available, prior to […]
As many as 70% of patients with SIRS, sepsis, or MOF have either a polyneuropathy or myopathy [Musc Nerve 32: 140, 2005], but usually these disorders are overshadowed by more obvious conditions. [NEJM 348: 745, 2003] Polyneuropathy is treated by prevention and tight glucose control – one study showed that glucose control can reduce the […]
There are three responses to mild blood loss: Stage 1) transcapillary refill, leaving an interstitial fluid deficit; Stage 2) activation of renin-angiotensin-aldosterone; Stage 3) production of erythrocytes within a few hours Stages of Shock (Severity) Parameter Class I Class II Class III Class IV % Blood loss < 15% 15 – 30% 30 – 40% […]
Anatomy of Labor Pain First Stage In the first stage of labor, pain travels via sympathetic nerve fibers (going through the inferior hypogastric plexus on the way to the sympathetic chain) that originate from the T10-L1 segments of the spinal cord (referred to the back as well as abdominal wall). Second Stage Pain for the […]
High Frequency Positive Pressure Ventilation (HFPPV) 60-120/min, small volumes. Can be open (ex. catheter in the mouth, output of gas does not follow any particular path) or closed (ex. catheter through an ETT, in which the outflow of gas follows a predetermined pathway). Closed is superior although not always possible. Can be used to ventilate […]
Ventilator Associated Pneumonia Secretions Saline should never be instilled into ETTs in order to break up secretions because as little as 5 cc can dislodge up to 300,000 bacterial colonies [Am J Crit Care 3: 444, 1994]. NAC can be instilled (direct instillation preferred over aerosol, which is irritative) to break up mucus plugs. Because […]
Anesthesia Boot Camp An Anesthesia Primer for CA1’s & Medical Students Submitted/Modified with permission from Roy G. Soto, MD (http://www.thesotos.net/anesthesia/) 1. Preoperative History and Physical An anesthesia preoperative evaluation is more focused than a medicine H&P, with specific attention on the airway, organ systems at potential risk for anesthetic complications, and the type of operation. […]
Commonly caused by antibiotics (PCN causes 95% of fatal reactions), anesthetics, radiocontrast (1:1000 to 1:14,000 injections, 10% of which are fatal [J Crit Illness 8: 332, 1993]), various foods, and insect stings. Presentation can be mild (flushing, rash, urticaria, abdominal cramping, diarrhea) or severe (angioedema, laryngeal edema, bronchospasm, hypotension). Treat with ABCs, 0.3 – 0.5 […]
Post-Operative Nausea and Vomiting Note: much of the following is a summary of the IARS consensus guidelines for PONV [Gan TJ et. al. Anesth Analg 97: 62, 2003; FREE Full-text at Anesthesia & Analgesia] and the society for Ambulatory Anesthesia Guidelines for PONV [Gan et. al. Ambulatory Anesthesiology 105: 1615, 2007] Incidence and Risk Factors […]
Many trauma patients will be hypovolemic, thus consider induction with ketamine (1-2 mg/kg) or etomidate (0.2-0.3 mg/kg) – also consider adding midazolam (induction dose 0.1-0.4 mg/kg), as the incidence of intraoperative recall is high in trauma patients. Most trauma patients cannot handle the same level of anesthesia as their healthier counterparts, thus paralysis is required […]
Introduction to Perioperative Arrhythmias While the incidence of perioperative arrhythmias is extremely high (the Multicenter Study of General Anesthesia reported a 70.2% incidence of tachycardia, bradycardia, or dysrhythmias in 17,201 patients having general anesthesia), only 1.6% of these will require clinically-significant management (antidysrhythmic drugs, electrical devices, or cardiopulmonary resuscitation) [Forrest J et al. Anesthesiology 72: […]
Background: occurs in 5% of U.S. population. Clinical triad of cough, wheezing, dyspnea. Often includes hyperresponsiveness to physical stimuli (including ETT). Triggered by infection (very common), airway irritants, allergens, drugs (aspirin and NSAIDs [leukotrienes], beta-antagonists, morphine [histamine release]). By definition, asthma is a reversible disease (a 12% increase in FEV1 following bronchodilator therapy is indicative […]
Pregnancy & Cardiac Arrest Most anesthesiologists have received Advanced Cardiac Life Support (ACLS) certification. Does that mean we know how to resuscitate a parturient following cardiac arrest? American Heart Association (AHA) ACLS courses generally don’t spend much time, if any, teaching obstetric-specific interventions. The Society for Obstetric Anesthesia and Perinatology, have developed a consensus statement […]
The PACO2 of an awake, preoxygenated adult with normal lungs rises 7 mm Hg/minute for the first 10 seconds, 2 mm Hg/min for the next 10 seconds, then 6 mm Hg/minute afterwards [Stock MC et. al. J Clin Anesth 1: 96, 1988], so essentially 6 mm Hg/min or 1 mm Hg every 10 seconds. According […]
Overview of Aortic Regurgitation Etiology Chronic aortic regurgitation, which is more common than acute, is most often due to rheumatic disease or a bicuspid valve, but can also be due to connective tissue disorders. It normally manifests as congestive heart failure when regurgitant volume approaches ~ 40% of SV, and is considered “severe” at 60% […]
Indications The axillary technique is ideal for operatiaons of the hand, elbow, and some forearm operations (provided that they are not innervated by the lateral cutaneous nerve of the forearm) Relevant Anatomy Landmarks and Surrounding Structures The most important landmark is the axillary artery, as the neurovascular bundle is oriented reliably around it – median […]
BIS monitoring made real time. When the original monitor display was created by Aspect Medical Systems, the decision to display only the BIS trace was made to be esthetically pleasing to the eye. Since the BIS value is a derived value, the algorithm requires 15-30 seconds to calculate. Trying to titrate anesthetics in real time […]
Overview of Aortic Stenosis Aortic stenosis is the most common cause of LV outflow obstruction (less common causes include HOCM, subvalvular stenosis, or, rarely, supravalvular stenosis). Etiology AS can be divided into congenital (bicuspid), rheumatic, or degenerative (calcific). If in concert with rheumatic fever, is almost always associated with mitral pathology. These patients have an […]
Pharmacology/Basic Science Vasopressors Used in the ICU Alpha Agonism Phenylephrine (Neosynephrine) at 10-200 μg/min: α1 Norepinephrine (Levophed) at 4-12 μg/min: α1 (high), α2 (high), β1 (moderate) Epinephrine at > 0.1 μg/kg/min: α1 (high), α2 (high), β1 (high), β2 (high) Beta Agonism Epinephrine at 0.005 – 0.02 μg/kg/min: β2 (high), β1 (moderate) Dobutamine at 2.5-10 μg/kg/min: […]
Tricuspid valve contains anterior (largest), posterior, and medial leaflets. Pulmonic valve contains the anterior, right, and left cusps and is 4 cm2 in area. Mitral valve is normally 4-6 cm2 and is made up of the anteromedial and posterolateral leaflets. The blood supply to the mitral chordae tendinae and papillary muscles is often in jeopardy. […]
Preoperative Evaluation and Questions: AS, AR, or both? If AS, how severe? Aortic valve opening: moderate AS = 0.7–0.9 cm2; critical AS = < 0.5 cm2 (normal = 2.6–3.5 cm2) Ao valve gradient: severe = > 50 mmHg Concurrent CAD? CHF? Esophageal stricture? surgery? injury? varices? (placement of TEE) AS is the most common valve […]
Hemodynamic Alterations The first sign of ventricular dysfunction is usually an increase in filling pressures (stroke volume is maintained but requires higher preload). This is followed by decreased stroke volume and increased heart rate. Cardiac output is the last variable to change (decompensation). The two measurements useful in distinguishing systolic from diastolic failure are the […]
Analgesia in the ICU The best assessment of pain control is patient response. However, in critically ill patients who cannot effectively communicate, use of body language or heart rate is probably an ineffective way to measure pain in the critically ill patient. [Crit Care Clin 15: 35, 1999] Opiates Fentanyl is probably superior to morphine […]
Usually presents with respiratory distress, hypotension, hypoxia. May lead to an anaphylactoid reaction that produces pulmonary hypertension and right heart failure (which can eventually progress to biventricular failure and cardiac arrest). Mortality rate is 60% [Clark SL et al. Am J Obstet Gynecol 172: 1158, 1995], and 70% of these deaths will be due to […]
Adrenal Insufficiency Predisposing conditions include major surgery, circulatory failure, septic shock, severe coagulopathy, and HIV infections. Reports of incidence in the ICU range from 0 – 30% [J Intensive Care Med 4: 35, 1988; Crit Care Clin 7: 23, 1991]. In those in septic shock, rates are probably 25 – 40%, and mortality in these […]
In the past, patients with abdominal injuries routinely underwent exploratory laparotomies for both diagnostic and therapeutic reasons, however with the advent of FAST scans and rapid, high-resolution spiral CT scanners, the added diagnostic benefit of the “ex-lap” has diminished significantly. Furthermore, advances in interventional radiology / angiography have made it possible to treat solid organ […]
Introduction Acute Kidney Injury or AKI is the new term for acute renal failure. This new terminology emphasizes the fact that kidney injury is a broad spectrum of functional derangement, and is significant no matter how minor the decrease in function. The term “renal failure” is often associated with the most severe degrees of impairment […]
Signs, Symptoms, Predisposition, and Diagnosis of ARDS Predisposing Factors and Mortality in ARDS The earliest signs of ARDS are tachypnea and progressive hypoxemia (often refractory to O2) in a predisposed patient. Within 24 hours the CXR should display bilateral infiltrates. Hallmarks are 1) Predisposing condition 2) PAO2/FIO2 < 200 3) Bilateral infiltrates 4) wedge < […]
ACLS for Cardiac Arrest in the Operating Room Cardiac arrest in the community is a fairly common problem for which rescusitation guidelines have been studied and developed. Cardiac arrest in the peri-operative setting is relatively rare,1 and for numerous reasons, knowing when to initiate CPR can be difficult.2 False alarms in the operating room occur […]
Uterine Blood Flow The uterine arteries provide the uterus with ~ 700 cc/min of maternal blood. The placenta is supplied by two umbilical arteries from the fetus. The fetus receives oxygenated blood from the placenta through a single umbilical vein. Effect of Common Vasoactive Drugs: Phenylephrine vs. Ephedrine There is minimal autoregulation in the uterine […]
Indications The interscalene technique is ideal for coverage of the lateral 2/3 of the clavicle (clavicular surgery will often be incomplete, as there is joint innervation by the cervical plexus), the shoulder, and the proximal humerus(note that when arthroscopic surgery is undertaken, the posterior arthroscopic port may require additional infiltration). Because the inferior trunk (C8-T1) […]
The Modern Approach to Modes of Mechanical Ventilation While modes have classically been divided up into pressure or volume controlled modes, a more modern approach describes ventilatory modes based on three characteristics – the trigger (flow versus pressure), thelimit (what determines the size of the breath), and the cycle (what actually ends the breath). In […]
Relevant Physiology Autoregulation maintains cerebral blood flow of 50 cc/100g/min over MAPs ranging from 50 – 150 cc/hr, although in hypertensives this range is shifted upward. While neurologic symptoms may arise at CBP > 20 cc/100g/m, the brain is critically compromised (electrical impairment ensues) at CBP < 20 cc/100g/m, and pump failure occurs at CBF […]
Contents 3 Misconceptions About Weaning 4 Weaning Parameters: Organ Systems Approach 5 Weaning Parameters: Bedside Parameters 5.1 Frequency-Volume Ratio 5.2 Maximum Inspiratory Pressure 5.3 Leak Test 6 Weaning Methods 6.1 T-piece weaning 6.2 Pressure support weaning 6.3 Protocol-Driven Weaning 7 Complicating Factors During Weaning 8 The Difficult Wean 8.1 Rapid breathing 8.2 Weak diaphragm 8.3 […]
The term “stress ulcer” is somewhat of a misnomer because unlike peptic ulcers, these lesions are very superficial. The primary cause of these ulcers is impaired blood flow, not gastric acidity [Crit Care Med 30: S351, 2002; Gastroenterol Clin North Am 19: 101, 1990]. Gastric erosions are present in 10 – 25% of patients admitted […]
Fundamental Treatment Strategies in Sepsis Initial Resuscitation (Level I) Begin as soon as recognized and not delayed pending ICU admission. Elevated lactate may identify tissue hypoperfusion in at-risk normotensive patients, however there is some dispute as to its precision as a tissue metabolic status monitor. During the first 6 hrs, the goals of initial resuscitation […]
Renal replacement therapy (RRT) began in 1977 with the use of continuous arteriovenous hemofiltration [Kramer P et al. Klin Wochenschr 55: 1121, 1977]. Since that time RRT has blossomed into a complex array of therapeutic modalities, each with its own indications, advantages, and disadvantages. Understanding RRT in the critical care (and in some cases, intraoperative) […]
Introduction The traditional normal temperature of 98.6 (37C) is derived from axillary measurements made in 1871. A more recent survey of oral temperatures revealed an average of 98.2 (36.8C) – by this survey, fever was defined as 99 (37.2C) in the early AM and 100 (37.8C) in the evening (Tmin is at 4 – 8:00 […]
Why Enteral Nutrition? Complete bowel rest is accompanied by progressive atrophy of the intestinal mucosa, which is evident after only a few days [Ann Surg 205: 681, 1987]. Glutamine is considered the principal metabolic fuel for intestinal epithelial cells and may be especially important in this regard [Nutrition 6: 199, 1990]. Lastly, bacterial translocation has […]
Classification of Antimicrobial Agents Bactericidal vs. Bacteriostatic Antimicrobial agents can be roughly divided into those which are bactericidal (they actively kill bacteria) and those which are bacteriostatic (they slow the growth of bacteria), although there is some overlap depending on the doses used and individual agents. Most antimicrobial agents in clinical use are bactericidal, including […]
Approaches to Fluid Management The “Classic” Approach to Fluid Management The “Classic” (read: outdated) approach to management of fluids in the perioperative setting involved trying to predict the amount of fluids needed based on a the duration and severity of a particular operation and empirically replacing fluids based on these estimates. IT IS PRESENTED HERE […]
Cerebral aneurysm surgery can be performed through a craniotomy or endovascularly (intra-arterial approach). Open aneurysm surgery through a craniotomy involves careful dissection to expose the aneurysm followed by placement of surgical clips to obliterate the aneurysm. Endovascular repair involves coil embolization of the aneurysm with subsequent thrombosis of the aneurysm dome/sac. The anatomy of the […]
- Clinical Neuroanesthesia a. Anesthesia for: i. Craniotomy (including awake techniques) 1. Tumor surgery 2. Epilepsy Surgery 3. Supra vs. Infra-tentorial surgery ii. Cerebrovascular Surgery iii. Endovascular Neurosurgery 1. Acute ischemic stroke 2. Aneurysm, AVM’s, Atherosclerotic disease iv. Neurotrauma 1. Craniectomy 2. Hematoma evacuation 3. Spine injury v. Endoscopic neurosurgery vi. Functional/stereotactic neurosurgery […]
Lumbosacral Plexus Blocks Introduction: The nerve supply to the lower extremity is derived from the lumbar and sacral plexuses. The lumbar plexus provides sensory innervation to the anterior thigh and to the medial portion of the lower leg via the saphenous nerve (distal branch of the femoral nerve), as well as the majority of the […]
Acalculous cholecystitis Acalculous cholecystitis is uncommon but can be fatal if missed [J Intensive Care Med 9: 235, 1994]. It may present with fever (this may be the only sign), nausea, vomiting, abdominal pain, and RUQ tenderness. LFT elevations are variable [World J Surg 1160, 1992]. It is classically considered to be more common in […]