Anaphylaxis — KFP-style written assessment

KFP 1 (10 marks)

A 19-year-old delivery driver collapses in your waiting room 15 minutes after a pharmacy antibiotic dose. He has stridor, generalised wheeze, flushing of the face and neck, and a blood pressure of 78/44 mmHg. Your nurse has already called the ambulance. ^[4]

1. State the immediate drug treatment — dose, route, site — and the repeat strategy. (3) ^{[24] [1]}
2. He receives one dose and improves partially but remains wheezy and hypotensive. List your next actions in order. (4) ^{[4] [29]}
3. The ambulance officer proposes an intravenous bolus of 0.5 mg adrenaline for speed. Critically appraise this proposal with numbers. (3) ^[5]

Model answers

1. Adrenaline (epinephrine) 0.5 mg — 0.5 mL of 1:1000 (1 mg/mL) — by deep intramuscular injection into the mid-anterolateral thigh, immediately; guidelines recommend 500 µg intramuscularly for teenagers and adults. Repeat every 5 minutes while airway, breathing or circulatory compromise persists. Diagnosis here is secure without any test: rapid onset after a likely allergen with two systems involved plus hypotension after a drug exposure. ^{[24] [4]}
2. Repeat intramuscular adrenaline every 5 minutes as needed; position supine with legs raised (semi-reclined given respiratory distress); high-flow oxygen; rapid intravenous fluid bolus 500–1000 mL for the hypotension — capillary leak drives shock; nebulised salbutamol for persistent bronchospasm. If he fails repeated intramuscular doses he meets the working definition of refractory anaphylaxis — unresponsive to several intramuscular doses — and needs escalation to a titrated intravenous adrenaline infusion (about 0.05–0.1 µg/kg/min) in a monitored setting with critical-care involvement. ^{[4] [29]}
3. Decline the bolus. In a 573-patient emergency cohort all four epinephrine overdoses occurred during intravenous bolus administration (13.3% vs 0% of intramuscular doses; OR 61.3), and cardiovascular adverse events complicated 10% of intravenous bolus doses versus 1.3% of intramuscular doses (OR 8.7). Intravenous bolus adrenaline is reserved for monitored settings; outside them it adds overdose and arrhythmia risk without adding speed that matters. ^[5]