| Abstract: | Malignant hyperthermia (MH) is a rare but potentially life-threatening emergency characterized by a hypermetabolic state which leads to pyrexia and muscle rigidity. It is a genetic disorder that displays autosomal dominant inheritance. Defects of the RyR1 and CACNA1S genes cause dysregulated calcium release within skeletal myocytes on exposure to triggering agents, causing tetanic contraction of the myocyte. Triggering agents are the halogenated volatile anaesthetic agents and suxamethonium chloride. Diagnosing MH involves genetic testing and an in-vitro contracture test. This is performed at specialist MH centres.An unexplained rise in end-tidal CO2 and tachycardia should prompt the anaesthetist to consider an MH crisis. This can occur at any time during an anaesthetic or within the ensuing hours. A previous uneventful general anaesthetic does not rule out a crisis happening on subsequent anaesthetics. Crisis management comprises of stopping the offending triggering agent and provision of a clean volatile-free anaesthetic circuit. Activated charcoal filters are useful for the sequestration of halogenated vapours. Dantrolene is the only available treatment and should be immediately available in every area providing anaesthetic assistance. Active body cooling should be implemented to target core body temperatures below 38.5°C. Supportive measures should be instigated until the reaction has subsided. Guidelines produced by the Association of Anaesthetists of Great Britain and Ireland and the European Malignant Hyperpyrexia Group are available to aid in the management of the MH-susceptible patient and an MH crisis. |
