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Hyperkalemia ECG — USMLE Step 3 MCQ

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HardEmergency MedicineHyperkalemia ECGUSMLE Step 3

A 71-year-old woman is brought 3 hours after ingesting a large amount of extended-release verapamil. She has junctional bradycardia at 38/min, blood pressure 68/40 mm Hg, glucose 246 mg/dL, and severe left-ventricular depression despite airway support, intravenous calcium, atropine, and norepinephrine. Which therapy should be added next with poison-center guidance?

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

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Correct answer: B — Begin high-dose insulin with dextrose and intensive glucose-potassium monitoring

The best answer is “Begin high-dose insulin with dextrose and intensive glucose-potassium monitoring”. Severe calcium-channel blocker poisoning causes bradycardia, vasodilation, impaired inotropy, and insulin resistance with hyperglycemia. High-dose insulin provides metabolic and direct inotropic support and is recommended early when shock persists, while dextrose and frequent glucose and potassium measurements prevent treatment complications. Calcium and vasopressors continue as needed; ECMO or other rescue therapies are considered for refractory shock.

Reference: AHA Guideline: Life-Threatening Calcium-Channel Blocker Poisoning: https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines/adult-and-pediatric-special-circumstances-of-resuscitation