Induction of general anaesthesia by rapid injection of propofol and dexmedetomidine or propofol and buthorphanol: cardiopulmonary and echocardiographic parameters in unpremedicated dogs

2011 The Authors. Veterinary Anaesthesia and Analgesia 20 2011 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists, 38, 1–35 Induction of general anaesthesia by rapid injection of propofol and dexmedetomidine or propofol and butorphanol: cardiopulmonary and echocardiographic parameters in unpremedicated dogs G Ravasio, L Borghi, D Fonda, P Brambilla, V Bronzo, J Cincotti & C Locatelli Universita` degli Studi di Milano, Facolta` di Medicina Veterinaria di Milano, via Celoria 10, 20133 (MI) Italy The aim was to compare quality of induction, echocardiographic and cardiopulmonary effects of two different general anaesthesia induction protocols. Twelve dogs (ASA I-II) were assigned randomly into two groups. Both groups received a rapid bolus of propofol (2.2 mg kg)1 IV) immediately followed by a rapid bolus of dexmedetomidine 3 lg kg)1 IV (group A) or butorphanol 0MAP, SAP (NIBP) were recorded and 2, 5, 10, 15, 20 minutes after drug administration. Induction quality, intubation time, additional propofol dose to achieve intubation, sedation score (Fernandez et al. 2005) and adverse effects were recorded. Echocardiogram was performed at baseline and immediately after tracheal intubation. Data were analyzed using repeated measures ANOVA and Wilcoxon test (p < 0.05). Induction quality, intubation time (A: 75 ± 25, B: 145 ± 66.8 seconds) were statistically different between groups, HR was statistically lower in group A compared to baseline (62 ± 23; 101 ± 23), fR was not statistically different between groups but lower than baseline in group A, NIBP was statistically higher in group A and lower in group B compared to baseline. Body temperature, SpO2, PE¢CO2 were not statistically different. No apnoea (>30 seconds) or emesis were recorded. Five group B dogs required additional propofol (1.1 ± 0.7 mg kg)1 IV) to achieve tracheal intubation. Left ventricular end-diastolic diameter was statistically lower in group B and statistically higher in group A compared to baseline. Cardiac output decrease was 18.5% in group A and 24.4% in group B. Quality of induction was better in group A. Echocardiographic parameters varied compared to baseline in both groups but remained within normal ranges for adult dogs (Cornell et al. 2004). References: Fernandez JG, Parodi E, Garcia P et al. (2005) Clinical action of subarachnoid sevoflurane in vivo: a study in dogs. Brit J Anaesth 95(4), 530– 534. Cornell CC, Kittleson MD, Della Torre P et al. (2004) Allometric scaling of M-Mode cardiac measurements in normal adult dogs. J Vet Intern med 18(3), 311–321..4 mg kg)1 IV (group B) administered by a blinded operator. Baseline HR,