title: Dose-finding study comparing three treatments of remifentanil in cats anesthetized with isoflurane undergoing ovariohysterectomy.
abstract: Objectives Three infusion rates of remifentanil were used in isoflurane-anesthetized cats undergoing ovariohysterectomy. The aim of this study was to identify a dosage regimen that would provide optimal anesthetic and surgical conditions, as well as to compare cardiovascular response to surgical stimulation, postoperative analgesia, anesthetic duration and quality of recovery among the tested remifentanil infusion rates. Methods Twenty-seven client-owned, mixed-breed adult healthy female cats were randomized to receive remifentanil 0.1 µg/kg/min (REMI01), remifentanil 0.2 µg/kg/min (REMI02) or remifentanil 0.4 µg/kg/min (REMI04). After premedication with acepromazine and induction of anesthesia with propofol, cats were mechanically ventilated and anesthesia was maintained at approximately 1.0 minimum alveolar concentration (MAC) of isoflurane (1.63% end-tidal isoflurane [ETISO]). Remifentanil infusion rate was increased or decreased by 20% if blood pressure had increased or decreased by 20% from previous values. Pulse rate (PR), systolic arterial pressure (SAP), esophageal temperature, pulse oximetry, end-tidal partial pressure of CO2and ETISOwere recorded at different time points during surgery. Meloxicam was administered before the end of surgery. Data within each treatment group were analyzed using a mixed-model ANOVA and Friedman's test followed by the Wilcoxon signed rank test. Bonferroni or Dunnett's post-hoc tests were used. The Kruskal-Wallis test followed by Dunn's post-hoc test were used to compare data between groups; significance was set at P <0.05. Results Time to sternal recumbency and time to standing were significantly longer in REMI04 than in the other groups. SAP was higher when compared with baseline in REMI01 and REMI02 groups than in REMI04. No significant difference in PR among groups was observed. One cat in REMI01 and another in REMI02 required postoperative rescue analgesia. Conclusion and relevance The dosage regimen of 0.4 µg/kg/min seemed to be the most appropriate to be used in cats undergoing ovariohysterectomy and anesthetized with 1.0 MAC of isoflurane.
authors.affiliation: 1 Graduate Program in Cardiovascular Sciences, College of Medicine, Fluminense Federal University (UFF), Niterói, RJ, Brazil.
authors.forename: Marcela L
authors.initials: ML
authors.lastname: Machado
authors.affiliation: 2 Department of Small Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA.
authors.forename: João Henrique N
authors.initials: JHN
authors.lastname: Soares
authors.affiliation: 3 Autonomous Veterinarian, Rio de Janeiro, RJ, Brazil.
authors.forename: Maria Alice
authors.initials: MA
authors.lastname: Kuster de Albuquerque Gress
authors.affiliation: 4 Heart Institute, São Paulo University, São Paulo, SP, Brazil.
authors.forename: Douglas
authors.initials: D
authors.lastname: Dos Santos E Castro
authors.affiliation: 5 Department of Large Animal Clinical Sciences. Anesthesia and Pain Management Service, University of Florida, Gainesville, FL, USA.
authors.forename: Kaleizu
authors.initials: K
authors.lastname: Teodoro Rosa
authors.affiliation: 6 Department of Pathology and Clinical Sciences, College of Veterinary Medicine, Fluminense Federal University, Niterói, RJ, Brazil.
authors.forename: Phillipe
authors.initials: P
authors.lastname: Bauer de Araujo Doria
authors.affiliation: 1 Graduate Program in Cardiovascular Sciences, College of Medicine, Fluminense Federal University (UFF), Niterói, RJ, Brazil.|7 Department of Physiology and Pharmacology, Biomedical Institute, Fluminense Federal University, Niterói, RJ, Brazil.
authors.forename: Fabio
authors.initials: F
authors.lastname: Otero Ascoli
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000758:Anesthesia / Q000662:veterinary*; D000762:Anesthesia Recovery Period; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D000818:Animals; D002320:Cardiovascular Physiological Phenomena; D002415:Cats; D004305:Dose-Response Relationship, Drug; D005260:Female; D007044:Hysterectomy / Q000662:veterinary; D007530:Isoflurane / Q000008:administration & dosage; D010052:Ovariectomy / Q000662:veterinary; D011182:Postoperative Care / Q000662:veterinary*; D011897:Random Allocation; D000077208:Remifentanil / Q000008:administration & dosage*; D013997:Time Factors
chemical_list: D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D007530:Isoflurane; D000077208:Remifentanil