Retrospective analysis of anaesthetics received by patients before susceptibility to malignant hyperpyrexia was recognized.

We have reviewed the anaesthetic histories of patients later found to be susceptible to malignant hyperpyrexia (MH). Many patients known to have this condition have been exposed to the known inducing agents previously, sometimes on more than on occasion. It is clear that insusceptibility to MH cannot be assumed from previous uneventful exposure to the known triggering agents and that all patients suspected of having inherited MH must be screened by in vivo muscle biopsy studies. No common factor could be found to explain this phenomenon.