title: Effect of nitrous oxide on the minimum alveolar concentration for sevoflurane and the minimum alveolar concentration derivatives that prevent motor movement and autonomic responses in dogs.
abstract: OBJECTIVE
  To investigate the effects of the concurrent administration of 70% N(2)O on the minimum alveolar concentration (MAC) for sevoflurane in dogs, the MAC derivative that blocks motor movement (MAC(NM)), and the MAC derivative that blocks autonomic responses (MAC(BAR)).
  
  
  METHODS
  7 adult sexually intact male mixed-breed dogs.
  
  
  METHODS
  For each dog, anesthesia was induced with sevoflurane delivered via a face mask. Initially, the baseline MAC, MAC(NM), and MAC(BAR) for sevoflurane were determined by use of a noxious stimulus (50 V, 50 Hz, and 10 milliseconds) applied subcutaneously over a midulnar region. Nitrous oxide (70%) was added to the breathing circuit, and MAC, MAC(NM), and MAC(BAR) were determined again. Percentage changes from the respective baseline concentrations for MAC, MAC(NM)' and MAC(BAR) were calculated after the administration of N(2)O.
  
  
  RESULTS
  Baseline median values for the MAC, MAC(NM), and MAC(BAR) for sevoflurane were 1.75%, 2.00%, and 2.50%, respectively. Addition of 70% N(2)O significantly decreased MAC, MAC(NM), and MAC(BAR) by 24.4%, 25.0%, and 35.2%, respectively, and these values did not differ significantly from each other.
  
  
  CONCLUSIONS
  Supplementation with 70% N(2)O caused a clinically important and significant decrease in the MAC, MAC(NM)' and MAC(BAR) for sevoflurane in dogs.
authors.affiliation: Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA. mrsed@utk.edu
authors.forename: Reza
authors.initials: R
authors.lastname: Seddighi
authors.forename: Christine M
authors.initials: CM
authors.lastname: Egger
authors.forename: Barton W
authors.initials: BW
authors.lastname: Rohrbach
authors.forename: Meredith
authors.initials: M
authors.lastname: Hobbs
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Doherty
mesh_terms: D000768:Anesthesia, General / Q000662:veterinary; D000769:Anesthesia, Inhalation / Q000662:veterinary; D018685:Anesthetics, Inhalation / Q000493:pharmacokinetics* / Q000494:pharmacology; D000818:Animals; D001341:Autonomic Nervous System / Q000187:drug effects*; D004285:Dogs / Q000502:physiology*; D008297:Male; D008738:Methyl Ethers / Q000493:pharmacokinetics* / Q000494:pharmacology; D009043:Motor Activity; D009609:Nitrous Oxide / Q000494:pharmacology*; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000378:metabolism*; D000077149:Sevoflurane
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D009609:Nitrous Oxide