March 18, 2024

Before we jump into PE, I had a pediatric airway foreign body case recently. No more bilateral decubitus x-rays. It’s high-res, low-dose CT. Know where I learned this? JournalFeed Top Picks! I have learned some game-changing things from Dr. Mattu, and special thanks to Dr. Stephanos with her PEM lit pearls. These videos have changed my practice. Check out this new video series for yourself! ~Clay Smith

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Written by Rebecca White

One third of eligible patients with high-risk pulmonary embolism (PE) receive systemic thrombolysis (ST) despite demonstrated mortality benefit. This review provides a comprehensive overview of current evidence on assessment and management of high-risk PE, with emphasis on reperfusion therapies.

Don’t just stand there, bust a clot!
High-risk PE, defined by ESC guidelines as cardiac arrest, obstructive shock (SBP <90mmHg), or persistent hypotension without alternative cause, accounts for only 5-10% of PE cases but has a disproportionately large effect on total PE mortality.1-4 Despite high mortality rates that may even be increasing, only small percentage of patients eligible for ST actually receive it.5,6 This narrative review includes 147 articles focusing on clinical assessment, pathophysiology, and management of patients with high-risk PE. Buckle up – it’s a wordy but important summary.

Clinical assessment:

• If patient is risk-stratified as high-risk, proceed directly to CT pulmonary angiography.
• If too unstable for CT, utilize history, exam, ultrasound, and other diagnostics to determine the etiology of shock.

Pathophysiology of right ventricular (RV) failure:

• When pressure in the pulmonary arteries increases significantly, compensatory mechanisms of the RV cannot keep up.
• Thus ensues the so-called “PE death spiral” of RV distention, decreased cardiac output and hemodynamic instability.

Management of hemodynamic instability:

• Give enough fluid to optimize preload, but not worsen RV over-distention (consider a 250-500mL bolus).
• Consider norepinephrine as a first-line vasopressor, followed by vasopressin. Avoid phenylephrine.
• Consider epinephrine for inotropic support, but beware of tachyarrhythmias. Avoid dobutamine or milrinone alone.

Management of respiratory failure:

• Utilize supplemental oxygen with goal SpO2 >90% to combat hypoxemia due to V/Q mismatch.
• Avoid positive pressure ventilation if possible. If intubation is necessary, optimize hemodynamics prior to induction.
• Consider inhaled pulmonary vasodilators for refractory hypoxemia.

Reperfusion therapies:

• Anticoagulation should be given unless absolutely contraindicated, even before diagnostic CT imaging if pretest probability is high. For unstable patients, unfractionated heparin is a first-line agent; keep a close eye to ensure levels are therapeutic. There is no evidence to support DOAC use in this population just yet.
• Standard-dose ST is recommended as first-line reperfusion therapy, barring any absolute contraindications. Reduced-dose thrombolytics can be considered if a relative contraindication exists. There is no established timeframe for ST administration in patients with high-risk PE, and no apparent difference between tenecteplase and alteplase.
• If there are major contraindications to ST or a patient continues to decompensate after ST, consider alternative reperfusion therapies such as surgical embolectomy and catheter-directed interventions.
• ECMO can be used as a bridge to reperfusion therapy in the crashing patient.
• In cardiac arrest, ST should be given if there is clinical concern for PE. Guidelines vary in recommended duration of cardiopulmonary resuscitation (CPR) following ST. Authors recommend continuing ACLS-guided CPR for at least 30 minutes after administration.

How will this change my practice?
Emergency clinicians should feel very prepared to manage high-risk PE, yet eligible patients don’t receive guideline-directed ST nearly as often as they should. With this in mind, I’ll continue to appraise my own management of high-risk PE patients in conjunction with our PE Response Team to ensure we are following guidelines and considering early reperfusion therapy.

Source
Rouleau SG, Casey SD, Kabrhel C, Vinson DR, Long B. Management of high-risk pulmonary embolism in the emergency department: A narrative review. Am J Emerg Med. Published online February 3, 2024. doi:10.1016/j.ajem.2024.01.039

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