title: Effects of lidocaine administration via continuous rate infusion on the minimum alveolar concentration of isoflurane in New Zealand White rabbits (Oryctolagus cuniculus).
abstract: OBJECTIVE
  To evaluate the effect of a continuous rate infusion (CRI) of lidocaine on the minimum alveolar concentration (MAC) of isoflurane in rabbits.
  
  
  METHODS
  Five 12-month-old female New Zealand White rabbits (Oryctolagus cuniculus).
  
  
  METHODS
  Rabbits were anesthetized with isoflurane. Baseline isoflurane MAC was determined by use of the tail clamp technique. A loading dose of lidocaine (2.0 mg/kg, IV) was administered followed by a CRI of lidocaine at 50 μg/kg/min. After 30 minutes, isoflurane MAC was determined. Another loading dose was administered, and the lidocaine CRI then was increased to 100 μg/kg/min. After 30 minutes, isoflurane MAC was determined again. Plasma samples were obtained for lidocaine analysis after each MAC determination.
  
  
  RESULTS
  Baseline isoflurane MAC was 2.09%, which was similar to previously reported values in this species. Lidocaine CRI at 50 and 100 μg/kg/min induced significant reductions in MAC. The 50 μg/kg/min CRI resulted in a mean plasma lidocaine concentration of 0.654 μg/mL and reduction of MAC by 10.5%. The 100 μg/kg/min CRI of lidocaine resulted in a mean plasma concentration of 1.578 μg/mL and reduction of MAC by 21.7%. Lidocaine also induced significant decreases in arterial blood pressure and heart rate. All cardiopulmonary variables were within reference ranges for rabbits anesthetized with inhalation anesthetics. No adverse effects were detected; all rabbits had an uncomplicated recovery from anesthesia.
  
  
  CONCLUSIONS
  Lidocaine administered as a CRI at 50 and 100 μg/kg/min decreased isoflurane MAC in rabbits. The IV administration of lidocaine may be a useful adjunct in anesthesia of rabbits.
authors.affiliation: Department of Clinical Science, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506.
authors.forename: Rodney W
authors.initials: RW
authors.lastname: Schnellbacher
authors.forename: James W
authors.initials: JW
authors.lastname: Carpenter
authors.forename: Diane E
authors.initials: DE
authors.lastname: Mason
authors.forename: Butch
authors.initials: B
authors.lastname: KuKanich
authors.forename: Hugues
authors.initials: H
authors.lastname: Beaufrère
authors.forename: Courtney
authors.initials: C
authors.lastname: Boysen
mesh_terms: D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D000818:Animals; D058126:Balanced Anesthesia / Q000379:methods* / Q000662:veterinary; D001794:Blood Pressure / Q000187:drug effects; D002853:Chromatography, Liquid; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007262:Infusions, Intravenous / Q000662:veterinary; D007530:Isoflurane / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008012:Lidocaine / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D013058:Mass Spectrometry; D011817:Rabbits
chemical_list: D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D008012:Lidocaine; D007530:Isoflurane