Evaluation of suspected Malignant Hyperthermia events during anaesthesia

Background: Malignant hyperthermia (MH), a metabolic myopathy triggered by volatile anesthetics and depolarizing muscle relaxants, is a potentially lethal complication of general anesthesia in susceptible patients. The implementation of modern volatile anesthetics that pretend to be less potent trigger substances and the recommended limitations of succinylcholine use are suggesting a considerable decline of fulminant MH cases. Aim of this study was the evaluation of incidence and severity of suspected MH episodes during general anesthesia in patients that were referred to the Wuerzburg MH unit between 2007 and 2011. Methods: With IRB approval data of patients that underwent muscle biopsy and in vitro contracture test (IVCT) between 2007 and 2011 were analyzed. Only patients with a history of suspected MH crisis were included in the study. The incidents were evaluated retrospectively using anesthetic documentations and medical records. Results: Between 2007 and 2011 a total of 124 patients had been tested. 19 of them were referred because of suspected MH events; 7 were diagnosed MH-susceptible, 4 MH-equivocal and 8 MH-non-susceptible according to IVCT. In a majority masseter spasm after succinylcholine had been the primary symptom. Cardiac arrhythmia and hypercapnia frequently occurred early in the course of events. Interestingly, dantrolene treatment was initiated in a few cases only. Discussion: MH is still an important anesthetic complication. Every anesthetist must be aware of this lifethreatening syndrome at any time. The rapid onset of adequate therapy is crucial to avoid major harm and possibly lethal outcome. Dantrolene must be readily available wherever MH triggering agents are used for anesthesia.