Perioperative Anaphylaxis

IgE-mediated (or pseudo-allergic) hemodynamic collapse from drug, latex, or transfusion exposure. Most common triggers in OR: NMBAs (rocuronium, succinylcholine), antibiotics, latex.

Recognition

•Sudden hypotension + ↑HR after drug administration
•Bronchospasm, ↑PIP, urticaria/flush, angioedema
•Often within minutes of induction or antibiotic dose

Steps

1
Stop the suspected trigger
2
Call for help, 100% O₂, secure airway if not already
3
Epinephrine titrated IV
10–100 mcg IV bolus q1–2 min, escalating to 0.1–1 mg if cardiac arrest. IM 0.3–0.5 mg if no IV access.
4
Rapid IV fluids
1–2 L NS or LR; up to 35 mL/kg may be needed (massive third-spacing).
5
Vasopressin 1–2 U bolus, then infusion
Especially if epi-refractory hypotension.
6
Adjunct: H1 + H2 blockers + steroid
Adjuncts only — they do not replace epi. Steroid for delayed/biphasic.
7
Bronchodilators if wheezing
Albuterol nebulized + IV ketamine 0.5 mg/kg or epi nebulizer.
8
Send tryptase 30 min, 2 h, and 24 h post-event
9
Refer to allergist with drug + latex panel

Drugs + doses

Drug	Dose	Note
Epinephrine	10–100 mcg IV q1–2 min; 1 mg IV if arrest
NS or LR	20 mL/kg bolus, repeat
Vasopressin	1–2 U IV bolus, then 0.01–0.04 U/min
Diphenhydramine (H1)	25–50 mg IV
Famotidine (H2)	20 mg IV
Hydrocortisone	100–200 mg IV
Glucagon	1–5 mg IV (for β-blocker–refractory cases)

Pitfalls

!Diphenhydramine + steroid alone → patient deteriorates. Epi first, always.
!Sugammadex can cause anaphylaxis itself (~1:2,500–20,000) — recognize.
!Tryptase normal ≠ rule out anaphylaxis (especially non-IgE pseudoallergy).

Sources

AAGBI 2024
WAO Guidelines 2020
ASA Practice Advisory

Anatomy reference

Sourced reference images. 4 matches for "immune system mast cell histamine".

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Education only — not a substitute for facility protocols, MOC certification, or clinical judgment. Always follow your institutional crisis algorithm and confirm doses against current package inserts.