title: Minimum infusion rate of alfaxalone for total intravenous anaesthesia after sedation with acepromazine or medetomidine in cats undergoing ovariohysterectomy.
abstract: OBJECTIVE
  To determine the induction doses, then minimum infusion rates of alfaxalone for total intravenous anaesthesia (TIVA), and subsequent, cardiopulmonary effects, recovery characteristics and alfaxalone plasma concentrations in cats undergoing ovariohysterectomy after premedication with butorphanol-acepromazine or butorphanol-medetomidine.
  
  
  METHODS
  Prospective randomized blinded clinical study.
  
  
  METHODS
  Twenty-eight healthy cats.
  
  
  METHODS
  Cats undergoing ovariohysterectomy were assigned into two groups: together with butorphanol [0.2 mg kg(-1) intramuscularly (IM)], group AA (n = 14) received acepromazine (0.1 mg kg(-1) IM) and group MA (n = 14) medetomidine (20 μg kg(-1) IM). Anaesthesia was induced with alfaxalone to effect [0.2 mg kg(-1) intravenously (IV) every 20 seconds], initially maintained with 8 mg kg(-1)  hour(-1) alfaxalone IV and infusion adjusted (±0.5 mg kg(-1)  hour(-1) ) every five  minutes according to alterations in heart rate (HR), respiratory rate (fR ), Doppler blood pressure (DBP) and presence of palpebral reflex. Additional alfaxalone boli were administered IV if cats moved/swallowed (0.5 mg kg(-1) ) or if fR >40 breaths minute(-1) (0.25 mg kg(-1) ). Venous blood samples were obtained to determine plasma alfaxalone concentrations. Meloxicam (0.2 mg kg(-1) IV) was administered postoperatively. Data were analysed using linear mixed models, Chi-squared, Fishers exact and t-tests.
  
  
  RESULTS
  Alfaxalone anaesthesia induction dose (mean ± SD), was lower in group MA (1.87 ± 0.5; group AA: 2.57 ± 0.41 mg kg(-1) ). No cats became apnoeic. Intraoperative bolus requirements and TIVA rates (group AA: 11.62 ± 1.37, group MA: 10.76 ± 0.96 mg kg(-1)  hour(-1) ) did not differ significantly between groups. Plasma concentrations ranged between 0.69 and 10.76 μg mL(-1) . In group MA, fR , end-tidal carbon dioxide, temperature and DBP were significantly higher and HR lower.
  
  
  CONCLUSIONS
  Alfaxalone TIVA in cats after medetomidine or acepromazine sedation provided suitable anaesthesia with no need for ventilatory support. After these premedications, the authors recommend initial alfaxalone TIVA rates of 10 mg kg(-1)  hour(-1) .
authors.affiliation: Equine Department, Vetsuisse Faculty, Section Anaesthesiology, University of Zurich, Zurich, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Schwarz
authors.forename: Karin
authors.initials: K
authors.lastname: Kalchofner
authors.forename: Julia
authors.initials: J
authors.lastname: Palm
authors.forename: Stephanie
authors.initials: S
authors.lastname: Picek
authors.forename: Sonja
authors.initials: S
authors.lastname: Hartnack
authors.forename: Regula
authors.initials: R
authors.lastname: Bettschart-Wolfensberger
mesh_terms: D000075:Acepromazine / Q000008:administration & dosage; D000762:Anesthesia Recovery Period; D000769:Anesthesia, Inhalation / Q000662:veterinary*; D000777:Anesthetics / Q000008:administration & dosage; D000818:Animals; D002371:Cat Diseases / Q000601:surgery*; D002415:Cats; D005260:Female; D006993:Hypnotics and Sedatives / Q000008:administration & dosage; D007044:Hysterectomy / Q000662:veterinary*; D020926:Medetomidine / Q000008:administration & dosage; D010052:Ovariectomy / Q000662:veterinary*; D011277:Pregnanediones / Q000008:administration & dosage; D011446:Prospective Studies
chemical_list: D000777:Anesthetics; D006993:Hypnotics and Sedatives; D011277:Pregnanediones; D000075:Acepromazine; C006477:alphaxalone; D020926:Medetomidine
keywords: acepromazine; alfaxalone; cat; medetomidine; total intravenous anaesthesia