A 22-year-old man with a documented episode of masseter spasm progressing to malignant hyperthermia during sevoflurane anaesthesia presents for elective surgery. If an inhalational technique must be used, which agent is safest?
- A Desflurane
- B Isoflurane
- C Nitrous oxide ✓
- D Sevoflurane with dantrolene prophylaxis
Correct answer: C. Nitrous oxide
Explanation
Nitrous oxide does not trigger malignant hyperthermia; the syndrome is caused by uncontrolled calcium release from the ryanodine receptor in skeletal muscle, and only the halogenated volatile agents act as triggers. All fluorinated ethers, including desflurane, isoflurane and sevoflurane, are contraindicated after a confirmed or strongly suspected episode, and dantrolene prophylaxis does not make them safe. The correct technique would otherwise be total intravenous propofol.
Reference: Miller's Anesthesia, 9th ed.
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