The Setup
You're three years out of intern year. Your last truly hairy anaphylaxis was probably during PGY-1 and you don't remember any of it because the room was on fire. Here's the refresher you didn't ask for.
Pearl 1 — Epi First. Not Steroids. Not Diphenhydramine. Epi.
If the patient has airway swelling, stridor, wheezing, hypotension, or any two-system reaction — 0.3–0.5 mg of 1:1000 IM epinephrine in the lateral thigh, now. Not when the steroid kicks in. Not after the Benadryl. The first dose is more important than any drug in the next 60 minutes.
Pearl 2 — Repeat It
Up to 35% of patients need a second dose within 5–10 minutes. Set a timer. If they're not visibly better, give it again.
Pearl 3 — Start the Drip Earlier Than You Think
If they've had two IM doses without sustained improvement, start an epinephrine infusion at 0.05–0.1 mcg/kg/min. Don't wait for them to crash a third time before you commit to the drip. The drip is the answer when they keep relapsing.
Pearl 4 — H1/H2 Blockers Are Adjuncts, Not Treatment
Diphenhydramine and famotidine treat the itching and hives. They don't treat the anaphylaxis. They're a tier-3 intervention. Give them. Don't mistake them for what's keeping the patient alive.
Pearl 5 — Observation Time Is Earned, Not Counted
The old "4-hour observation rule" is dead. Modern data: uncomplicated, single-dose-IM-epi responders, observe 1 hour. Two-dose, history of asthma, severe initial reaction, slow-to-respond — observe 6+ hours because biphasic reactions cluster there. Don't anchor to a single number; risk-stratify.
The One That Trips Senior Residents
Beta-blocked patients can be refractory to epinephrine. If your patient is on metoprolol or carvedilol and isn't responding — glucagon 1–5 mg IV. Bypasses the beta receptor. Quick. Effective. Pulled out of the trick bag once a year, max.
Resources
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