title: Incidence of malignant hyperthermia reactions in 2,214 patients undergoing muscle biopsy.
abstract: To determine the incidence of malignant hyperthermia (MH) reactions after trigger-free anaesthesia in a large population of MH-susceptible (MHS) patients, the charts of 2,214 patients who underwent elective muscle biopsy for malignant hyperthermia were reviewed. Either general or regional anaesthesia with non-triggering drugs was used. For general anaesthesia, the trachea was intubated in the absence of muscle relaxants. The halothane/caffeine contracture test was performed on the biopsied muscle. Suspected MH reactions were identified according to their site of occurrence (in the operating room, recovery room or ward). Ninety-seven percent of patients received a general anaesthetic; 3% received a regional anaesthetic or field block. Of the 2214 patients whose muscles were biopsied, 1082 patients were biopsy-positive for MH. Five patients in whom MH reactions were diagnosed in the recovery room were all subsequently proved to be biopsy-positive for MH. Four of the five received intravenous dantrolene as part of their therapy; the fifth received only symptomatic therapy as parenteral dantrolene was not commercially available. All patients recovered completely from their reactions. We conclude that the incidence of MH reactions in biopsy-positive patients who receive a trigger-free anaesthetic for minor surgery is small (0.46%, (0.15-1.07%, 95% CI)). These reactions occur in the immediate postoperative period.
authors.affiliation: Department of Anaesthesia, Hospital for Sick Children, Toronto, Ontario.
authors.forename: A S
authors.initials: AS
authors.lastname: Carr
authors.forename: J
authors.initials: J
authors.lastname: Lerman
authors.forename: M
authors.initials: M
authors.lastname: Cunliffe
authors.forename: M E
authors.initials: ME
authors.lastname: McLeod
authors.forename: B A
authors.initials: BA
authors.lastname: Britt
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000762:Anesthesia Recovery Period; D000765:Anesthesia, Conduction; D000768:Anesthesia, General; D001706:Biopsy; D002110:Caffeine; D002648:Child; D002675:Child, Preschool; D003286:Contracture / Q000175:diagnosis; D003620:Dantrolene / Q000627:therapeutic use; D004198:Disease Susceptibility; D006221:Halothane; D006801:Humans; D015994:Incidence; D007223:Infant; D007431:Intraoperative Complications; D008305:Malignant Hyperthermia / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology*; D009407:Nerve Block; D012189:Retrospective Studies
chemical_list: D002110:Caffeine; D003620:Dantrolene; D006221:Halothane