A previously healthy 8-year-old presents with acute onset wheeze, generalized urticaria, and hypotension after eating peanuts at a school picnic. HR 140, BP 70/40, SpO2 90%. The single most critical initial intervention is:

• A IV diphenhydramine 1 mg/kg
• B Nebulized salbutamol and IV hydrocortisone
• C IV fluid bolus 20 mL/kg isotonic saline
• D IM epinephrine 0.01 mg/kg (1:1000) into anterolateral thigh ✓

Explanation

Anaphylaxis with cardiovascular compromise (hypotension, SpO2 90%) requires immediate IM epinephrine as the cornerstone of treatment. Epinephrine reverses bronchospasm, reduces mucosal edema, causes vasoconstriction, and improves cardiac output. The anterolateral thigh (vastus lateralis) is the preferred injection site for fastest absorption. IV antihistamines and corticosteroids are adjuncts and must never delay epinephrine. IV fluids help distributive shock but epinephrine must come first. Delayed epinephrine in anaphylaxis is the leading preventable cause of death.

Reference: Ghai Essential Pediatrics, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.