Malignant hyperthermia during laparoscopic hernia repair23-year-old man, 90 kg, very muscular, for elective laparoscopic inguinal hernia repair under sevoflurane

The patient

The examiner asks

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1. Consider

   What are the risks in this fit young man?

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   • A fit 23-year-old having his first anaesthetic, no family history known, for laparoscopic hernia repair. Patient
   • No anaesthetic history and no family history: MH susceptibility can't be ruled out. Disease
   • Insufflated CO2 will lift his ETCO2 and can mimic MH. Surgery
   • Dantrolene and the MH kit checked and in theatre before we start. Disease

2. Crisis

   Thirty minutes after insufflation, ETCO2 is 68 mmHg despite doubling his ventilation. HR 128, temperature 37.9 °C, and his jaw is rigid. What do you do?

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   • MH algorithm: CO2 rising despite more ventilation, tachycardia and rigidity in him; not insufflation. (Crisis)
   • Trigger off: sevoflurane stopped, help called, and the surgeon finishes fast.
   • Pure oxygen at a fresh gas flow of 10 L/min or higher, hyperventilation, and charcoal filters fitted.
   • Propofol and opioid keep him asleep.
   • Dantrolene 2.5 mg/kg IV fast, repeated every 5 minutes until signs settle, up to 10 mg/kg.
   • Each vial mixed in sterile water, not saline, or it precipitates; I need extra hands.
   • Blood gas, potassium, CK and clotting sent now.

3. Crisis

   Ten minutes later: temperature 39.2 °C, K+ 7.1 mEq/L, peaked T waves and runs of VT. What now?

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   • Hyperkalaemia from muscle breakdown; more dantrolene is the most effective fix. (Crisis)
   • Calcium chloride, 10 mg/kg, given IV to steady his myocardium.
   • Insulin 10 units with 50 mL of 50% dextrose.
   • Bicarbonate 1–4 mEq/kg, guided by his gases.
   • VT treated by the adult algorithm; no calcium channel blockers alongside dantrolene.
   • Cooling: ice packs, cold saline 20 mL/kg, stopping at 38 °C.
   • Urine above 1–2 mL/kg/h, alkalinised, to protect his kidneys from myoglobin.

4. Plan

   He stabilises. What next?

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   • ICU for 24–48 hours; MH can recur in up to half of cases. (After surgery)
   • Maintenance dantrolene: 1 mg/kg six-hourly, or 0.25 mg/kg/h running, for 1–2 days.
   • Serial CK, potassium, clotting and kidney function.
   • Referral for testing: muscle contracture test or genetic testing.
   • His blood relatives are told they may carry it too.
   • MH alert on his record, a letter for him, and the case reported.