title: Effect of dexmedetomidine constant rate infusion on the bispectral index during alfaxalone anaesthesia in dogs.
abstract: OBJECTIVE
  To assess the effect of two rates of infusion of dexmedetomidine on the bispectral index (BIS) in dogs anaesthetized with alfaxalone constant rate infusion (CRI).
  
  
  METHODS
  Prospective, randomized, 'blinded' experimental study.
  
  
  METHODS
  Six healthy Beagles (three females and three males).
  
  
  METHODS
  Dogs received as premedication saline (group D0), 1 μg kg(-1) (group D1) or 2 μg kg(-1) (group D2) dexmedetomidine, intravenously (IV). Anaesthesia was induced with alfaxalone (6 mg kg(-1) to effect IV) and maintained with alfaxalone at 0.07 mg kg(-1)  minute(-1) and a CRI of saline (D0) or dexmedetomidine 0.5 μg kg(-1)  hour(-1) (D1) or 1 μg kg(-1)  hour(-1) (D2) for 90 minutes. BIS, electromyography (EMG), signal quality index (SQI) and suppression ratio (SR) were measured at 10 minute intervals and the median values were calculated. Nociceptive stimuli were applied every 30 minutes and BIS and cardiorespiratory values were compared before and after stimuli. Cardiorespiratory parameters were recorded throughout the study.
  
  
  RESULTS
  BIS and EMG values differed significantly among groups, being lower in D2 (71 ± 8) than in D0 (85 ± 10) and D1 (84 ± 9). SQI was always over 90% and SR was zero throughout all the treatments. There were no significant differences between pre- and post-stimulus values of BIS, EMG and SQI for any treatment, although in D0 and D1, heart rate, respiratory rate and arterial pressures increased significantly after the nociceptive stimulus.
  
  
  CONCLUSIONS
  Administration of dexmedetomidine (2 μg kg(-1)  + CRI 1 μg kg(-1)  hour(-1) ) decreases the BIS values and avoids the autonomic responses of a nociceptive stimulus during alfaxalone anaesthesia at 0.07 mg kg(-1)  minute(-1) in dogs. However, further studies are needed to verify whether this combination produces an adequate degree of hypnosis under surgical situations.
authors.affiliation: Department of Animal Medicine and Surgery, Anaesthesia Unit, Veterinary Faculty, University of Córdoba, Córdoba, Spain.
authors.forename: Rocio
authors.initials: R
authors.lastname: Navarrete
authors.affiliation: Department of Animal Medicine and Surgery, Anaesthesia Unit, Veterinary Faculty, University of Córdoba, Córdoba, Spain.
authors.forename: Setefilla
authors.initials: S
authors.lastname: Quirós-Carmona
authors.affiliation: Department of Animal Medicine and Surgery, Anaesthesia Unit, Veterinary Faculty, University of Córdoba, Córdoba, Spain.
authors.forename: María Del M
authors.initials: Mdel M
authors.lastname: Granados
authors.affiliation: Department of Animal Medicine and Surgery, Anaesthesia Unit, Veterinary Faculty, University of Córdoba, Córdoba, Spain.
authors.forename: Rafael J
authors.initials: RJ
authors.lastname: Gómez-Villamandos
authors.affiliation: Department of Animal Medicine and Surgery, Anaesthesia Unit, Veterinary Faculty, University of Córdoba, Córdoba, Spain.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Domínguez
authors.affiliation: Department of Animal Medicine and Surgery, Anaesthesia Unit, Veterinary Faculty, University of Córdoba, Córdoba, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Férnandez-Sarmiento
authors.affiliation: Department of Animal Medicine and Surgery, Anaesthesia Unit, Veterinary Faculty, University of Córdoba, Córdoba, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Muñoz-Rascón
authors.affiliation: Department of Animal Medicine and Surgery, Anaesthesia Unit, Veterinary Faculty, University of Córdoba, Córdoba, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Funes
authors.affiliation: Department of Animal Medicine and Surgery, Anaesthesia Unit, Veterinary Faculty, University of Córdoba, Córdoba, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Morgaz
mesh_terms: D000758:Anesthesia / Q000379:methods / Q000662:veterinary; D000777:Anesthetics / Q000008:administration & dosage*; D000818:Animals; D003243:Consciousness / Q000187:drug effects*; D020927:Dexmedetomidine / Q000008:administration & dosage*; D004285:Dogs; D004569:Electroencephalography / Q000379:methods / Q000662:veterinary; D004576:Electromyography / Q000662:veterinary; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D010147:Pain Measurement / Q000662:veterinary; D011277:Pregnanediones / Q000008:administration & dosage*; D011446:Prospective Studies
chemical_list: D000777:Anesthetics; D011277:Pregnanediones; D020927:Dexmedetomidine; C006477:alphaxalone
keywords: alfaxalone; anaesthesia; bispectral index; dexmedetomidine; dog