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Cauda equina syndrome — MRCEM SBA MCQ

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HardSpineCauda equina syndromeMRCEM SBA

A patient taking digoxin develops vomiting, confusion, potassium 6.1 mmol/L, complete heart block and runs of bidirectional ventricular tachycardia. Which treatment most directly reverses the life-threatening toxic mechanism?

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Correct answer: D — Administer digoxin immune Fab with continuous rhythm monitoring

The best answer is “Administer digoxin immune Fab with continuous rhythm monitoring”. Hyperkalaemia, high-grade block and ventricular arrhythmia indicate life-threatening digoxin toxicity and require digoxin immune Fab. Fab binds free digoxin and reverses sodium–potassium-ATPase inhibition, addressing both electrical instability and potassium disturbance. Atropine, lidocaine or magnesium may be useful adjuncts, and pacing can be hazardous or ineffective before antidote. Calcium is not the antidote and should not delay Fab. Amiodarone has interaction and proarrhythmic concerns, while late charcoal cannot reverse established severe systemic toxicity.

Reference: Digoxin toxicity consensus review: https://pmc.ncbi.nlm.nih.gov/articles/PMC10599802/