title: Clinical presentation, treatment, and complications of malignant hyperthermia in North America from 1987 to 2006.
abstract: BACKGROUND
  We analyzed cases of malignant hyperthermia (MH) reported to the North American MH Registry for clinical characteristics, treatment, and complications.
  
  
  METHODS
  Our inclusion criteria were as follows: AMRA (adverse metabolic/musculoskeletal reaction to anesthesia) reports between January 1, 1987 and December 31, 2006; "very likely" or "almost certain" MH as ranked by the clinical grading scale; United States or Canadian location; and more than one anesthetic drug given. An exclusion criterion was pathology other than MH; for complication analysis, patients with unknown status or minor complications attributable to dantrolene were excluded. Wilcoxon rank sum and Pearson exact chi(2) tests were applied. A multivariable model of the risk of complications from MH was created through stepwise selection with fit judged by the Hosmer-Lemeshow statistic.
  
  
  RESULTS
  Young males (74.8%) dominated in 286 episodes. A total of 6.5% had an MH family history; 77 of 152 patients with MH reported >or=2 prior unremarkable general anesthetics. In 10 cases, skin liquid crystal temperature did not trend. Frequent initial MH signs were hypercarbia, sinus tachycardia, or masseter spasm. In 63.5%, temperature abnormality (median maximum, 39.1 degrees C) was the first to third sign. Whereas 78.6% presented with both muscular abnormalities and respiratory acidosis, only 26.0% had metabolic acidosis. The median total dantrolene dose was 5.9 mg/kg (first quartile, 3.0 mg/kg; third quartile, 10.0 mg/kg), although 22 patients received no dantrolene and survived. A total of 53.9% received bicarbonate therapy. Complications not including recrudescence, cardiac arrest, or death occurred in 63 of 181 patients (34.8%) with MH. Twenty-one experienced hematologic and/or neurologic complications with a temperature <41.6 degrees C (human critical thermal maximum). The likelihood of any complication increased 2.9 times per 2 degrees C increase in maximum temperature and 1.6 times per 30-minute delay in dantrolene use.
  
  
  CONCLUSIONS
  Elevated temperature may be an early MH sign. Although increased temperature occurs frequently, metabolic acidosis occurs one-third as often. Accurate temperature monitoring during general anesthetics and early dantrolene administration may decrease the 35% MH morbidity rate.
authors.affiliation: Department of Anesthesiology H187, The North American Malignant Hyperthermia Registry of MHAUS, Penn State College of Medicine, Hershey, Pennsylvania 17033, USA. mlarach@gmail.co
authors.forename: Marilyn Green
authors.initials: MG
authors.lastname: Larach
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Gronert
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Allen
authors.forename: Barbara W
authors.initials: BW
authors.lastname: Brandom
authors.forename: Erik B
authors.initials: EB
authors.lastname: Lehman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000777:Anesthetics / Q000009:adverse effects; D002648:Child; D002675:Child, Preschool; D003620:Dantrolene / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008305:Malignant Hyperthermia / Q000150:complications / Q000175:diagnosis / Q000628:therapy; D008875:Middle Aged; D009125:Muscle Relaxants, Central / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D000777:Anesthetics; D009125:Muscle Relaxants, Central; D003620:Dantrolene