ICU · Resuscitation

Anaphylaxis in the ICU

Also known as Anaphylactic shock · Refractory anaphylaxis · Biphasic anaphylaxis · Intravenous adrenaline · Glucagon for beta-blocked anaphylaxis

Anaphylaxis is a severe, life-threatening systemic hypersensitivity reaction. Diagnosis: NIAID/FAAN clinical criteria — acute onset after a likely allergen with skin or mucosal involvement plus respiratory compromise, hypotension, or end-organ dysfunction. Management: IM adrenaline into the anterolateral thigh (adult dose 0.01 mg/kg to a maximum of 0.5 mg, repeated every 5 minutes in life-threatening anaphylaxis), supine with legs elevated, high-flow oxygen, aggressive IV crystalloid. Refractory: IV adrenaline infusion after 2 to 3 IM doses; IV glucagon if beta-blocked (guideline recommendation despite limited evidence); vasopressin, methylene blue and ECMO as rescue. Biphasic reactions: median onset 11 hours (range 0.2 to 72 hours) — observe at least 6 hours; 6 to 12 hours practical. Paired tryptase: acute 30 minutes to 2 hours from onset, baseline at least 24 hours after resolution. Common triggers: drugs (antibiotics, NMBAs), foods, insect stings, radiocontrast.