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.
⚡ Rehearsal mode
Walk the algorithm step by step
9 steps · click-through one at a time. Forces you to pre-read each action before moving on — the way you should rehearse the real thing.
Recognition
- •Sudden hypotension + ↑HR after drug administration
- •Bronchospasm, ↑PIP, urticaria/flush, angioedema
- •Often within minutes of induction or antibiotic dose
Steps
- 1Stop the suspected trigger
- 2Call for help, 100% O₂, secure airway if not already
- 3Epinephrine titrated IV10–100 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.
- 4Rapid IV fluids1–2 L NS or LR; up to 35 mL/kg may be needed (massive third-spacing).
- 5Vasopressin 1–2 U bolus, then infusionEspecially if epi-refractory hypotension.
- 6Adjunct: H1 + H2 blockers + steroidAdjuncts only — they do not replace epi. Steroid for delayed/biphasic.
- 7Bronchodilators if wheezingAlbuterol nebulized + IV ketamine 0.5 mg/kg or epi nebulizer.
- 8Send tryptase 30 min, 2 h, and 24 h post-event
- 9Refer 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/BSACI 2021 (Anaesthesia 76:654)
- NAP6 Report 2018
- WAO Anaphylaxis Guidelines 2020 Update
- ASA Practice Advisory on Perioperative Anaphylaxis
Anatomy reference
Sourced reference images. 4 matches for "immune system mast cell histamine".
Browse the full image library →
Other crisis algorithms
- Malignant Hyperthermia (MH)
Hypermetabolic crisis triggered by volatile anesthetics or succinylcholine in genetically susceptible patients (RYR1, CACNA1S). Treat with dantrolene immediately.
- Amniotic Fluid Embolism (AFE)
Rare, often fatal obstetric emergency — anaphylactoid syndrome of pregnancy. Sudden hemodynamic collapse, hypoxemia, and DIC during labor, delivery, or postpartum (within 30 min).
- LAST (Local Anesthetic Systemic Toxicity)
Cardiovascular and CNS toxicity from inadvertent IV injection or systemic absorption of local anesthetic. Bupivacaine highest cardiotoxicity. Ropivacaine + lidocaine slightly safer.
- Laryngospasm
Reflex closure of the vocal cords from light-anesthesia airway stimulation. Common in pediatrics, recent URI, and emergence. Untreated → hypoxia → bradycardia → arrest.
- High / Total Spinal
Cephalad spread of neuraxial local anesthetic causing apnea + cardiovascular collapse. Most common with epidural-to-subarachnoid migration in OB.
- Intraoperative Pulmonary Embolism
Sudden ↑PA pressure → RV failure → cardiovascular collapse. May be thrombus, fat (long-bone fracture, IM rod), gas (laparoscopy CO₂, sitting craniotomy), or amniotic.
