Managing Patients at Risk

Once an increased risk of MH susceptibility is confirmed the management of anaesthesia is founded on the need to avoid exposure of the patient to triggering agents.

MH is a time-weighted dose response phenomenon and trace amounts of inhalational anaesthetics will not trigger malignant hyperthermia. Published procedures for the preparation of anaesthetic machines are based on reducing the delivered concentration of volatile anaesthetics to less than 5 ppm, but this is likely to provide a large margin of safety.

The principles of preparation of an anaesthetic machine or workstation involve exchange of components that can adsorb the inhalational anaesthetic and flushing the system with 100% oxygen for a period that is dependent on the complexity of the internal workings of the workstation. The manufacturer’s information should be consulted for the recommended period of flushing of the anaesthetic workstation.

If activated charcoal filters are available then all anaesthetic workstations can be ready to use for an MH risk patient in five minutes or less. We therefore recommend that all anaesthetic departments acquire activated charcoal filters. The activated charcoal filters are also recommended for use in management of an acute MH crisis.