title: Clinical effects of a constant rate infusion of remifentanil, alone or in combination with ketamine, in cats anesthetized with isoflurane.
abstract: OBJECTIVE
  To evaluate the effects of a constant rate infusion of remifentanil, alone or in combination with ketamine, in healthy cats anesthetized with isoflurane.
  
  
  METHODS
  Randomized, controlled, clinical trial.
  
  
  METHODS
  23 cats undergoing elective ovariohysterectomy.
  
  
  METHODS
  Cats were premedicated with acepromazine and morphine; anesthesia was induced with propofol and maintained with isoflurane. Cats were given constant rate infusions of remifentanil (20 μg/kg/h [9 μg/lb/h], IV; n = 8), remifentanil and ketamine (0.5 mg/kg [0.23 mg/lb], then 1.8 mg/kg/h [0.82 mg/lb/h], IV; 7), or crystalloid fluids (8). The anesthesiologist was blinded to treatment group, end-tidal isoflurane concentration, and vaporizer setting. Heart rate, systolic arterial blood pressure, respiratory rate, end-tidal partial pressure of CO2, temperature, and end-tidal isoflurane concentration were monitored; recovery scores were assigned.
  
  
  RESULTS
  There were no significant differences among treatment groups with respect to age, body weight, surgery time, anesthesia time, time to extubation, recovery score, or cardiorespiratory variables. End-tidal isoflurane concentration was significantly reduced in cats given remifentanil and ketamine (mean ± SD, 0.63 ± 0.4%), compared with concentration in cats given crystalloid fluids (1.22 ± 0.5%) but not compared with concentration in cats given remifentanil alone (1.03 ± 0.4%). Compared with cats given crystalloid fluids, mean isoflurane requirement was reduced by 48.3% in cats given remifentanil-ketamine and 15.6% in cats given remifentanil alone.
  
  
  CONCLUSIONS
  At the dosages administered, a constant rate infusion of remifentanil-ketamine resulted in a significant decrease in the isoflurane requirement in healthy cats undergoing ovariohysterectomy. However, significant differences in cardiovascular variables were not observed among treatment groups.
authors: Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC J2S 2M2, Canada.
authors: Paulo V M
authors: PV
authors: Steagall
authors: Monica
authors: M
authors: Aucoin
authors: Beatriz P
authors: BP
authors: Monteiro
authors: Maxim
authors: M
authors: Moreau
authors: Brad T
authors: BT
authors: Simon
authors: Patrick M
authors: PM
authors: Burns
mesh_terms: D000778:Anesthetics, Dissociative / Q000008:administration & dosage / Q000494:pharmacology; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D002415:Cats; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D007044:Hysterectomy / Q000662:veterinary*; D007530:Isoflurane / Q000008:administration & dosage / Q000494:pharmacology*; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology*; D010052:Ovariectomy / Q000662:veterinary*; D010880:Piperidines / Q000008:administration & dosage / Q000494:pharmacology*; D000077208:Remifentanil
chemical_list: D000778:Anesthetics, Dissociative; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D010880:Piperidines; D007649:Ketamine; D007530:Isoflurane; D000077208:Remifentanil