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MH Post-Crisis Monitoring — FRCA Final MCQ

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ModerateGeneral AnaesthesiaMH Post-Crisis MonitoringFRCA Final

A 38-year-old man (ASA I) undergoes an emergency appendicectomy under general anaesthesia. In recovery he has a core temperature of 38.8°C, masseter rigidity was noted at induction, and his ETCO2 was rising throughout the case. CK returns at 45000 U/L. He is diagnosed with malignant hyperthermia. After initial dantrolene treatment and stabilisation, what is the recommended duration of post-crisis monitoring in ICU?

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Correct answer: A — 24-48 hours

Following a malignant hyperthermia crisis, patients should be monitored in ICU/HDU for a minimum of 24-48 hours even after apparent clinical resolution. This is because MH can recur (re-triggering) in up to 25% of cases, typically within 6-12 hours. Monitoring includes: continuous ECG, temperature, urine output (target >2 mL/kg/hr to prevent myoglobin-induced AKI), serial CK levels, potassium, and calcium. Dantrolene 1 mg/kg IV should be continued every 4-6 hours for at least 24 hours. Referral to the MH investigation unit is mandatory.

Reference: AAGBI – 2020 – Malignant hyperthermia crisis guidelines; EMHG – 2024 – MH crisis recognition and management