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Malignant hyperthermia

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Clinical Manifestations

  1. Elevation of ETCO2, unexplained tachycardia, tachypnoea (or breathing against ventilator), sweating, skin mottling, cyanosis, overheating soda lime
  2. Hypertonus skeletal muscle
    1. after succinylcholine
        a) failure skeletal muscle to relax
        b) severe muscle faciculations
        c) masseter spasm
    2. later during anaesthesia with inhalation agents e.g. halothane, isoflurane, sevoflurane
  3. A rapid rise in body temperature
  4. Metabolic derangement
    1. Hypercarbia, metabolic acidosis
    2. Hyperkalaemia
    3. Myoglobinaemia
    4. Renal failure
    5. Coagulopathy
    6. CK rise
    7. Dysrythmias

Management

  • Discontinue inhalational anaesthetic agents
  • Call for help
  • Contact o/c Anaesthetist
  • Intubate, hyperventilate with 100% O2
  • Drugs
    • Immediate Dantrolene 2.5 mg/kg iv, up to 10 mg/kg (initial dose available in Operating Rooms)
    • Late dantrolene 1 mg/kg 6 hourly for 48 h
    • Sodium Bicarbonate according to blood gas status
    • Mannitol 0.5 g/kg to maintain urine output (NB mannitol present in dantrolene mix)
  • Active cooling
  • Fluid bolus 20 ml/kg (cooled), repeated as required
  • Dextrose/Insulin (1 ml/kg 50% glucose + 0.1 U/kg/h insulin) to control K+
  • Maintain urine output 1 ml/kg/h

Consider

  • Labetolol 0.2-1 mg/kg iv followed by 1-3 mg/kg/h for tachyarrthmias
  • Fasciotomies if severe muscle damage with compartment syndrome

Monitoring

  • Temperature - central and peripheral
  • Invasive arterial monitoring
  • CVP
  • Urinary catheter
  • ABG
  • Serum electrolytes (Na, K, Cl, Ca, Phos)
  • Coagulation
  • CK, myoglobin assays
  • Cerebral status

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Document Control

  • Date last published: 28 February 2011
  • Document type: Clinical Guideline
  • Services responsible: Paediatric Intensive Care Unit
  • Editor: John Beca
  • Review frequency: 2 years