Screening for malignant hyperthermia susceptibility.

In vitro pharmacological testing of isolated muscle strips surgically removed under general anaesthesia from 10 members of a known MH family enabled identification of three MH positive individuals. Diagnosis of MH susceptibility was based on increased sensitivity to low concentrations of caffeine and the presence of halothane-induced contractures in MH susceptible muscle. Dantrolene sodium 15 mg/l completely prevented halothane-induced contractures in two muscle strips from one of the MH positive cases. The successful anaesthetic management of known MH patients is described, as is the successful management of a hyperthermic episode during recovery in one of the MH positive cases.