Perioperative anaphylaxis — FFICM MCQ

Correct answer: A — Give intramuscular or intravenous adrenaline according to severity and setting

The correct answer is A, give intramuscular or intravenous adrenaline according to severity and setting. This presentation (hypotension, bronchospasm, facial swelling immediately after induction, rising airway pressure, falling SpO2) is anaphylaxis, and adrenaline is the first-line, life-saving treatment that reverses the underlying mediator-driven vasodilation, capillary leak and bronchoconstriction via alpha and beta adrenergic effects. In the perioperative setting, where IV access is already established and the patient is monitored, IV adrenaline titrated in small boluses (or infusion) by an experienced anaesthetist is appropriate, whereas IM adrenaline remains the default outside theatre. Current UK guidance is explicit that adrenaline must not be delayed for any other intervention once life-threatening anaphylaxis is recognised. Why the other options are wrong: E. Chlorphenamine: antihistamines are third-line adjuncts with no evidence of benefit in the acute life-threatening phase and must never be given before or instead of adrenaline. C. Wait for serum tryptase: tryptase is a retrospective diagnostic aid taken at defined intervals after the event; awaiting its result before treating would be fatal in a hypotensive, hypoxic patient. D. Nebulised salbutamol as sole therapy: this addresses bronchospasm alone and does nothing for the profound hypotension and angio-oedema, so it cannot be sole therapy. B. Hydrocortisone and observe: corticosteroids have a delayed onset of action, no longer have strong evidence for preventing biphasic reactions, and observation without adrenaline in a shocked, hypoxic patient risks cardiac arrest. Key point: In perioperative anaphylaxis with cardiovascular or respiratory compromise, adrenaline (IM outside theatre, cautious titrated IV boluses/infusion in the monitored perioperative setting) is the immediate, non-negotiable first-line treatment; all other drugs are adjuncts that must never delay it.

Reference: Resuscitation Council UK, Emergency treatment of peri-operative anaphylaxis: Resuscitation Council UK algorithm for anaesthetists (Anaesthesia, 2024); Emergency Treatment of Anaphylaxis: Guidelines for Healthcare Providers (Resuscitation Council UK, 2021), https://www.resus.org.uk/library/additional-guidance/guidance-anaphylaxis