title: Effects of intravenous lidocaine, ketamine, and the combination on the minimum alveolar concentration of sevoflurane in dogs.
abstract: OBJECTIVE
  To evaluate the effects of intravenous lidocaine (L) and ketamine (K) alone and their combination (LK) on the minimum alveolar concentration (MAC) of sevoflurane (SEVO) in dogs.
  
  
  METHODS
  Prospective randomized, Latin-square experimental study.
  
  
  METHODS
  Six, healthy, adult Beagles, 2 males, 4 females, weighing 7.8 - 12.8 kg.
  
  
  METHODS
  Anesthesia was induced with SEVO in oxygen delivered by face mask. The tracheas were intubated and the lungs ventilated to maintain normocapnia. Baseline minimum alveolar concentration of SEVO (MAC(B)) was determined in duplicate for each dog using an electrical stimulus and then the treatment was initiated. Each dog received each of the following treatments, intravenously as a loading dose (LD) followed by a constant rate infusion (CRI): lidocaine (LD 2 mg kg(-1), CRI 50 microg kg(-1)minute(-1)), lidocaine (LD 2 mg kg(-1), CRI 100 microg kg(-1) minute(-1)), lidocaine (LD 2 mg kg(-1), CRI 200 microg kg(-1) minute(-1)), ketamine (LD 3 mg kg(-1), CRI 50 microg kg(-1) minute(-1)), ketamine (LD 3 mgkg(-1), CRI 100 microg kg(-1) minute(-1)), or lidocaine (LD 2 mg kg(-1), CRI 100 microg kg(-1) minute(-1)) + ketamine (LD 3 mg kg(-1), CRI 100 microg kg(-1) minute(-1)) in combination. Post-treatment MAC (MAC(T)) determination started 30 minutes after initiation of treatment.
  
  
  RESULTS
  Least squares mean +/- SEM MAC(B) of all groups was 1.9 +/- 0.2%. Lidocaine infusions of 50, 100, and 200 microg kg(-1) minute(-1) significantly reduced MAC(B) by 22.6%, 29.0%, and 39.6%, respectively. Ketamine infusions of 50 and 100 microg kg(-1) minute(-1) significantly reduced MAC(B) by 40.0% and 44.7%, respectively. The combination of K and L significantly reduced MAC(B) by 62.8%.
  
  
  CONCLUSIONS
  Lidocaine and K, alone and in combination, decrease SEVO MAC in dogs. Their use, at the doses studied, provides a clinically important reduction in the concentration of SEVO during anesthesia in dogs.
authors: Department of Small Animal Clinical Sciences, University of Tennessee, Knoxville, TN 37996, USA. jwilso62@utk.edu
authors: Jeffrey
authors: J
authors: Wilson
authors: Thomas J
authors: TJ
authors: Doherty
authors: Christine M
authors: CM
authors: Egger
authors: Andrew
authors: A
authors: Fidler
authors: Sherry
authors: S
authors: Cox
authors: Barton
authors: B
authors: Rohrbach
mesh_terms: D000768:Anesthesia, General / Q000662:veterinary*; D019162:Anesthetics, Combined / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D000818:Animals; D018592:Cross-Over Studies; D004285:Dogs / Q000378:metabolism / Q000502:physiology*; D005260:Female; D007262:Infusions, Intravenous / Q000662:veterinary; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology; D008012:Lidocaine / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008738:Methyl Ethers / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D011650:Pulmonary Alveoli / Q000378:metabolism*; D000077149:Sevoflurane
chemical_list: D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D008738:Methyl Ethers; D000077149:Sevoflurane; D007649:Ketamine; D008012:Lidocaine