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Lithium toxicity — RCPSC EM MCQ

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HardToxicologyLithium toxicityRCPSC EM

A patient presents three hours after a large sustained-release verapamil ingestion with HR 36/min, BP 74/40 mmHg and rising lactate despite IV fluid and calcium. What treatment should be started with critical-care and poison-centre support?

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Correct answer: C — Start high-dose insulin with dextrose and monitoring

The best answer is “Start high-dose insulin with dextrose and monitoring”. Refractory bradycardic shock after major calcium-channel-blocker exposure requires escalation in a monitored critical-care setting. High-dose insulin euglycaemia therapy is a key treatment and requires frequent glucose and potassium monitoring, alongside vasopressors and other measures chosen with a poison centre. Delay and beta-blockade are dangerous.

Reference: Ontario Poison Centre: Regular insulin availability and high-dose insulin euglycemia therapy: https://www.ontariopoisoncentre.ca/Newsandevents/news-archive/2026/change-in-regular-insulin-vial-availability/