title: The dose-response relationship and regional distribution of lactate after intramuscular injection of halothane and caffeine in malignant hyperthermia-susceptible pigs.
abstract: We hypothesized that IM halothane and caffeine injection increases local lactate concentration dose-dependently in malignant hyperthermia-susceptible (MHS) and nonsusceptible (MHN) pigs and that the hypermetabolic reaction measured by regional distribution of lactate and carbon dioxide is limited to a small muscle volume. Microdialysis probes were placed in the hindlimbs of 7 MHS and 7 MHN pigs and perfused with Ringer's solution. After equilibration, boluses of increasing halothane and caffeine concentrations were injected. For the second hypothesis regarding regional distribution, microdialysis probes were positioned in 7 MHS and 6 MHN pigs at the injection site for halothane and caffeine and at a distance of 10 mm and 25 mm. Lactate was measured in the dialysate by spectrophotometry. In addition, PCO2 was measured in the halothane experiments. Halothane and caffeine increased IM lactate dose-dependently in MHS pigs significantly more than in MHN pigs. Lactate and PCO2 were increased only at the injection site but not at 10 mm and 25 mm distance. MH susceptibility leads to a leftward shift of the dose-response curve for IM lactate after local injection of halothane and caffeine. The increase of lactate and carbon dioxide levels after local MH trigger injection is limited to a small area around the probe.
authors.affiliation: Department of Anesthesiology, University of Wuerzburg, Wuerzburg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Schuster
authors.forename: Hendrik
authors.initials: H
authors.lastname: Schöll
authors.forename: Martin
authors.initials: M
authors.lastname: Hager
authors.forename: Rainer
authors.initials: R
authors.lastname: Müller
authors.forename: Norbert
authors.initials: N
authors.lastname: Roewer
authors.forename: Martin
authors.initials: M
authors.lastname: Anetseder
mesh_terms: D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002110:Caffeine / Q000008:administration & dosage / Q000494:pharmacology*; D002245:Carbon Dioxide / Q000097:blood; D004198:Disease Susceptibility; D004305:Dose-Response Relationship, Drug; D006221:Halothane / Q000008:administration & dosage / Q000494:pharmacology*; D007273:Injections, Intramuscular; D019344:Lactic Acid / Q000378:metabolism*; D008305:Malignant Hyperthermia / Q000175:diagnosis / Q000378:metabolism*; D017551:Microdialysis; D013552:Swine
chemical_list: D018685:Anesthetics, Inhalation; D002245:Carbon Dioxide; D019344:Lactic Acid; D002110:Caffeine; D006221:Halothane