Dantrolene Malignant Hyperthermia — MFDS Part 1 MCQ

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HardPharmacologyDantrolene Malignant HyperthermiaMFDS Part 1

During general anaesthesia for maxillofacial surgery, a patient who has received suxamethonium and sevoflurane develops a rapidly increasing end-tidal carbon dioxide despite increased ventilation, tachycardia, generalised muscle rigidity, metabolic acidosis and a rising core temperature. Which medical emergency should be suspected and treated promptly with intravenous dantrolene alongside supportive measures?

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Correct answer: D — Malignant hyperthermia

The correct answer is **A, malignant hyperthermia**. Exposure to a volatile anaesthetic and suxamethonium, followed by otherwise unexplained rising end-tidal carbon dioxide, tachycardia, rigidity, acidosis and increasing temperature, indicates an anaesthetic-triggered hypermetabolic crisis. Intravenous dantrolene is specifically indicated, together with immediate withdrawal of triggering agents and supportive management. It reduces pathological calcium release from the skeletal-muscle sarcoplasmic reticulum. Anaphylaxis more typically causes hypotension, bronchospasm and cutaneous signs without marked rigidity or hypercapnia. Thyroid storm is not acutely linked to anaesthetic triggers. Neuroleptic malignant syndrome usually follows dopamine-antagonist exposure and evolves over hours or days. Serotonin syndrome follows serotonergic drugs and commonly causes clonus and hyperreflexia rather than the characteristic anaesthetic-associated pattern.

Reference: Norgine Pharmaceuticals Ltd. Dantrium IV 20 mg powder for solution for injection, Summary of Product Characteristics, sections 4.1 and 5.1. Updated 18 May 2026. https://www.medicines.org.uk/emc/product/1097/smpc