Trigger-Free Anaesthesia

Anaesthesia without using known triggers for MH, namely:

Indications

Absolute:

  • Known malignant hyperthermia

Relative:

  • Potential malignant hyperthermia
    • Skeletal muscular disease
      • Exercise-induced rhabdomyolysis
      • Central core disease
      • Centronuclear myopathy
      • Congenital fiber type disproportion
      • Multiminicore disease
      • King-Denborough syndrome
    • Family history
    • Geographic location
  • Neuromuscular disease
    Associated with hyperkalaemia and rhabdomyolysis, but not MH.
    • Duchenne muscular dystrophy
    • Becker muscular dystrophy

Preparation

Consider either:

  • Use of a dedicated vapour-free machine
  • Flushing of machine
    Time consuming. Requires:
    • Remove vapourisers
    • Attach a fresh:
      • Circuit
      • Reservoir bag
      • Soda lime
    • Washout machine
      As per manufacturers guidelines, but may be up to 60-90 minutes at 10L/min of 100% oxygen.
  • Use of activated charcoal filters
    • Change circuit as above
    • Flush circuit at maximal flow rate
    • Insert activated charcoal filters on both expiratory and inspiratory limb
    • Machine can be used:
      • At maximal flow rate for 30 minutes
      • At 3L/min thereafter
      • Each set of filters can be used for up to 12 hours

Ensure availability of:

  • Temperature monitoring
  • Active cooling
    • Blankets
    • Ice
    • Cold saline
  • Dantrolene

Anaesthesia

Performed with:

  • Intravenous induction
  • Nitrous oxide may be used as an adjuvant
  • Maintenance with TIVA

References

  1. EMHG. Preparation of Anaesthetic Workstations for MH suspected or susceptible patients. Accessed 7/2019.