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Tricyclic overdose — DIPIMC MCQ

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HardMedical EmergenciesTricyclic overdoseDIPIMCDipIMC

A 30-year-old took a large overdose of amitriptyline two hours ago. She is drowsy and tachycardic, and her ECG shows a broad QRS of 140 ms with a tall R wave in lead aVR. She then has a brief seizure. Which treatment is most specifically indicated?

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Correct answer: E — Intravenous sodium bicarbonate

A broad QRS with an R wave in aVR after tricyclic overdose reflects sodium-channel blockade, and intravenous sodium bicarbonate is the specific treatment, narrowing the QRS and reducing the risk of arrhythmia and seizures. Flumazenil is contraindicated because it can precipitate seizures, and amiodarone may worsen conduction. Calcium does not address sodium-channel blockade. Pearl: a QRS wider than around 100 ms after tricyclic overdose predicts seizures and arrhythmia and prompts bicarbonate, guided by TOXBASE.

Reference: TOXBASE; JRCALC Clinical Guidelines