Why Use Push Dose Pressors? To buy yourself some time with your super hypotensive patients!!
Ensure your patient's perfusion status while you are trying to:
intubate managing transient hypotension preparing a drip preparing a central line
Know which medication to use based on clinical presentation of patient. Dr. Scott Weingart's Easy Push Dose Printout (It has photos!) Epinephrine alpha 1&2, beta 1&2 agonist = inopressor (Increase in myocardial contraction, heart rate, and peripheral vascular resistance)
Epinephrine Push Dose Concentration 10mcg/mL (1:100,000) vs. cardiac dose (1:10,000) Onset Immediate - 1 minute Duration 5-10 minutes Dose 5-20mcg every 2-5 minutes (0.5-2mL)
Preparation
Draw up 9mL of Normal Saline in an empty 10mL syringe (updated - see below) Attach a syringe and draw up 1mL of epinephrine from the pre-filled cardiac dose amp (Epinephrine 100mcg/mL) Shake a little, Place a label: Epinephrine 10mcg/mL
Phenylephrine alpha 1 agonist = increase in peripheral vascular resistance Heart rate remains the same. Watch out for reflex bradycardia.
Phenyelphrine Push Dose Concentration 100mcg/mL
Onset Immediate - 1 minute Duration 10-20 minutes Dose 50-200mcg every 2-5 minutes (0.5-2mL)
Preparation
Draw up 1mL of phenylephrine (10mg/mL concentration vial) Inject into NS 100mL bag Shake a little, Place a label: Phenylephrine 100mcg/mL Use as a drip or draw up in a syringe.
Super Nerdy Receptor Information Beta Receptors
Tissue
Receptor Subtype
Heart
beta1
Adipose Tissue
beta1, beta3?
Vascular Smooth Muscle
beta2
Airway Smooth Muscle
beta2
Beta1 Agonist Increases contractile force & HR. Activation of beta1 receptors in the atria and ventricles but the ventricles are really effected - thus increasing myocardial contraction. HR increases because SA node, AV node and the His-Purkinjie system are activated.
Beta 2 Agonist Relaxes smooth muscles
Alpha1 & Alpha 2 Agonist
Constriction of vascular smooth muscle. Myocardial Alpha 1 may have a positive inotropic effect. No clear understanding on Alpha 2 receptors at this moment.
Epinephrine & NE has equal affinity to both alpha 1 and alpha 2 receptors. However, Epinephrine has a higher affinity to beta 2 receptors. So effects are dose dependent. Initially will activate beta 2 receptors so relaxes vascular smooth muscle and decrease peripheral resistance, but at higher doses, epinephrine will also bind to alpha 1 receptors which is a potent vasoconstrictor and will dominate as epinephrine concentrations are higher.
Phenylephrine is a pure alpha 1 agonist.
Vasoconstriction of both arterial and venous vessels. Great for someone who has tachycardia/tachyarrhythmia but also hypotensive. Can cause reflex bradycardia.
Update 8/6/2017 "Concentration" used to differentiate final concentration versus dosing, to have clear language.
Update 8/8/2017 Brought to my attention by Craig Button, RN - There have been reported cases of serious medication errors due to mixing medications using pre-filled saline flushes and not labeling them. Therefore, I am going to change the recommended preparation of mixing epinephrine push dose concentrations. The LAST thing I want is to hear about unlabeled saline flushes with epinephrine lying around, and/or causing harm to patients. These medications should be respected so PLEASE LABEL ALL PREPARATIONS!! Original text is here. Blog post has been updated above.
Original Text: Epinephrine Push Dose Concentration Preparation
Take a NS 10mL flush and squeeze out air bubbles and saline so 9mL remains Attach a syringe and draw up 1mL of epinephrine from the pre-filled cardiac dose amp (Epinephrine 100mcg/mL) Shake a little, Place a label: Epinephrine 10mcg/mL
Now listen to the episode.... References: Scott Weingart. EMCrit Podcast 6 – Push-Dose Pressors. EMCrit Blog. Published on July 10, 2009. Accessed on August 3rd 2017. Available at [https://emcrit.