During rapid sequence induction with succinylcholine, a patient develops masseter muscle rigidity immediately after drug administration. Bag-mask ventilation is easy, and SpO2 remains 99%. What is the MOST appropriate next step?
- A Allow the succinylcholine to wear off, wake the patient, and plan awake intubation
- B Proceed with intubation attempt using direct laryngoscopy while oxygenation is maintained
- C Switch immediately to rocuronium and continue
- D Administer dantrolene 2.5 mg/kg IV immediately and cancel surgery ✓
Explanation
Isolated masseter spasm after succinylcholine is a warning sign for malignant hyperthermia (MH) susceptibility and mandates treating as MH until proven otherwise; dantrolene should be prepared or administered and the triggering agent (volatile anaesthetic, if started) stopped. Proceeding with surgery without treating the potential MH trigger is unsafe. Masseter spasm after succinylcholine in a child or young adult carries up to a 50% association with MH susceptibility, so the safest course is to abort the trigger and administer dantrolene if other signs emerge. Simply allowing the drug to wear off does not address the underlying MH risk.
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.