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Anaphylaxis — USMLE Step 3 MCQ

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HardEmergency MedicineAnaphylaxisUSMLE Step 3

A monitored adult with anaphylactic shock remains hypotensive after three correctly timed intramuscular epinephrine doses and rapid isotonic crystalloid. Airway and oxygenation are supported, IV access is secure, and the patient does not take a beta blocker. What is the next epinephrine strategy?

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Correct answer: D — Begin titrated intravenous epinephrine infusion with continuous monitoring

The best answer is “Begin titrated intravenous epinephrine infusion with continuous monitoring”. Persistent shock despite repeated appropriate intramuscular epinephrine and fluid resuscitation is refractory anaphylaxis and requires escalation to a carefully titrated intravenous epinephrine infusion in a monitored setting. A rapid IV bolus risks arrhythmia and dosing error; glucagon is particularly considered when beta blockade impairs response, while antihistamines and corticosteroids do not reverse shock.

Reference: CDC: Preventing and Managing Adverse Reactions: https://www.cdc.gov/vaccines/hcp/imz-best-practices/preventing-managing-adverse-reactions.html