Anaphylaxis

Recognize it under anesthesia - Unexplained hypotension or collapse, bronchospasm and rising airway pressures, and flushing or edema — think anaphylaxis; the cutaneous signs may be hidden under drapes.

Epinephrine first - Epinephrine is the first-line treatment — give it early (IM, or titrated IV by severity) and don't delay for second-line agents.

Stop the trigger and support - Remove the likely trigger, give 100% oxygen, resuscitate with fluids for the distributive shock, and secure the airway.

Common anesthetic triggers - Neuromuscular blockers, antibiotics, latex, and chlorhexidine are frequent culprits; ask about allergies and use latex precautions when indicated.

Adjuncts and follow-up - Antihistamines and steroids are second-line, not a substitute for epinephrine; send a tryptase level, watch for a biphasic reaction, and refer for allergy workup.

Anaphylaxis is a severe, rapid, IgE-mediated (or non-immune) hypersensitivity reaction with massive mediator release causing bronchospasm, vasodilation and capillary leak (distributive shock), angioedema, and urticaria.

Under anesthesia it's a life-threatening emergency, and common triggers are exactly the drugs and materials we use — neuromuscular blockers, antibiotics, latex, and chlorhexidine. The presentation can be masked by drapes and anesthesia, so cardiovascular collapse and rising airway pressures may be the first signs. Epinephrine is the treatment.