title: Intramuscular injection of malignant hyperthermia trigger agents induces hypermetabolism in susceptible and nonsusceptible individuals.
abstract: OBJECTIVE
  A new minimally invasive metabolic test for the diagnosis of susceptibility for malignant hyperthermia measuring intramuscular p(CO(2)) and lactate following local application of caffeine and halothane in humans was recently proposed. The present study tested the hypothesis that a more simplified test protocol allows a differentiation between malignant hyperthermia susceptible (MHS) and malignant hyperthermia nonsusceptible (MHN) and control individuals.
  
  
  METHODS
  With approval of the local ethics committee and informed consent, microdialysis and p(CO(2)) probes with attached microtubing were placed into the lateral vastus muscle of six MHS, seven MHN and seven control individuals. Following equilibration, boluses of 500 microl caffeine 80 mmol l(-1) and halothane 10 vol% dissolved in soybean oil were injected locally. p(CO(2)) and lactate were measured spectrophotometrically.
  
  
  RESULTS
  The maximal rate of p(CO(2)) increase was significantly higher in MHS than in MHN and control individuals following application of halothane and caffeine, respectively. Intramuscular caffeine injection leads to a significantly higher increase of local lactate levels in MHS than in MHN and control individuals, whereas halothane increased local lactate levels in all investigated groups. Haemodynamic and systemic metabolic parameters did not differ between the investigated groups.
  
  
  CONCLUSIONS
  Local caffeine and halothane injection increased intramuscular metabolism in MHS individuals significantly more than in the two other groups. In contrast to previous investigations, direct injection of the concentrations of halothane described here increased lactate and p(CO(2)) even in MHN skeletal muscle.
authors.affiliation: Department of Anesthesiology, University of Würzburg, Würzburg, Germany. metterlein_t@mail.klinik.uni-wuerzburg.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Metterlein
authors.forename: Frank
authors.initials: F
authors.lastname: Schuster
authors.forename: Peter
authors.initials: P
authors.lastname: Kranke
authors.forename: Norbert
authors.initials: N
authors.lastname: Roewer
authors.forename: Martin
authors.initials: M
authors.lastname: Anetseder
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002110:Caffeine / Q000009:adverse effects*; D002245:Carbon Dioxide / Q000737:chemistry; D005260:Female; D006221:Halothane / Q000009:adverse effects*; D006801:Humans; D007273:Injections, Intramuscular / Q000379:methods*; D007773:Lactates / Q000378:metabolism; D008297:Male; D008305:Malignant Hyperthermia / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000187:drug effects; D010100:Oxygen / Q000737:chemistry; D013024:Soybean Oil
chemical_list: D007773:Lactates; D002245:Carbon Dioxide; D002110:Caffeine; D013024:Soybean Oil; D010100:Oxygen; D006221:Halothane