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Anaphylaxis — MRCGP AKT MCQ

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HardEmergency MedicineAnaphylaxisMRCGP AKTUKMLAPARAMRCEM SBAMRCP Part 1PSA

A patient with amitriptyline poisoning has QRS 168 ms, ventricular ectopy and blood pressure 78/44 mmHg despite initial fluids. Which intervention most directly reverses the cardiotoxic mechanism?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: B — Give sodium bicarbonate and monitor QRS narrowing

The best answer is “Give sodium bicarbonate and monitor QRS narrowing”. Tricyclics block fast myocardial sodium channels. Hypertonic sodium bicarbonate supplies sodium and raises pH, reducing drug binding and improving conduction and blood pressure; boluses are repeated according to ECG and clinical response while avoiding excessive alkalosis or sodium load. Class I and some class III antiarrhythmics can worsen conduction. Lipid rescue is reserved for refractory specialist-managed cases.

Reference: GEMNet guideline for tricyclic antidepressant overdose: https://pubmed.ncbi.nlm.nih.gov/21436332/