Anaphylaxis in the ICU

• Give adrenaline 0.5 mg IM into the anterolateral thigh IMMEDIATELY and repeat q5 min; true anaphylaxis has no contraindication.
• Lie flat with legs up, give high-flow O₂, place 2 large-bore IVs, push 1–2 L rapid saline; nebulized adrenaline for stridor, early airway for angioedema.
• Antihistamines and steroids come only AFTER adrenaline; they are never first-line.
• On β-blockers, give glucagon 1–5 mg IV; watch 6–24 h for biphasic reactions and send home with 2 auto-injectors.
• An adrenaline nasal spray is now an approved needle-free option for discharge kits, alongside two auto-injectors.

Acute Care of Patients With Anaphylaxis

• Anaphylaxis: acute onset, skin/mucosal involvement plus respiratory compromise and/or reduced blood pressure
• Remove the trigger; supine with legs elevated; high-flow oxygen; call for help
• Into the anterolateral thigh inject epinephrine 0.3–0.5 mg IM (1:1,000), repeated every 5 min as needed
• Place two large-bore IVs; 0.9% saline 1–2 L rapidly for hypotension
• Once epinephrine is in, add: diphenhydramine 25–50 mg IV + H₂-blocker + hydrocortisone 100 mg IV (or methylprednisolone)
• Nebulized albuterol for bronchospasm; nebulized epinephrine for stridor/laryngeal edema; ready early intubation
• Refractory: epinephrine infusion 2–10 µg/min; glucagon 1–5 mg IV when on β-blockers
• Watch for 4–6 h (up to 24 h when severe/asthmatic); discharge with 2 epinephrine auto-injectors plus allergy referral — biphasic reactions occur in up to 20%