Evaluation of 119 anaesthetics received after investigation for susceptibility to malignant hyperthermia.

A questionnaire was sent to the first 371 patients investigated for MH susceptibility at the Danish MH Register, in order to assess sequelae from the muscle biopsy and possible subsequent anaesthetic complications. The purpose was to evaluate both the safety of anaesthetizing MH-susceptible (MHS) patients without the use of trigger agents, and the safety of giving trigger agents to non-susceptible (MHN) patients. Eighty-eight per cent of patients alive replied to the questionnaire. Of these, 22% complained about discomfort at the site of the biopsy, 2% had experienced problems when needing a subsequent anaesthetic, and 0.9% had had trouble when applying for life or accident insurance. The median observation period for all patients following the muscle biopsy was 5.5 years (range 27 months-11 years). During this period, 36 MHS patients had been anaesthetized 52 times (28 general and 23 regional anaesthetics, data missing in one case) without any MH-related complications. None of the patients had received prophylactic dantrolene. Three MHE patients had received non-trigger anaesthetic agents on three occasions without development of MH. Thirty-five MHN patients had been anaesthetized 64 times, and 13 of these MHN patients had received trigger agents 26 times without any signs of MH. An estimate of the probability of clinical MH developing in MHN patients subsequently anaesthetized with trigger agents was found to be 0-24.7% (95% confidence limits), whereas the probability of clinical MH developing in MHS patients anaesthetized with non-trigger agents was 0-9.7% (95% confidence limits).