A comparison of the effects of two different doses of ketamine used for co-induction of anaesthesia with a target-controlled infusion of propofol in dogs

摘要

To assess the cardiorespiratory and hypnotic-sparing effects of ketamine co-induction with target-controlled infusion of propofol in dogs. Prospective, randomized, blinded clinical study. Ninety healthy dogs (ASA grades I/II). Mean body mass 30.5 pl SD 8.6 kg and mean age 4.2 pl 2.6 years. All dogs received pre-anaesthetic medication with acepromazine (0.03 mg kgp#) and morphine (0.2 mg kgp#) administered intramuscularly 30 minutes prior to induction of anaesthesia. Heart rate and respiratory rate were recorded prior to pre-medication. Animals were allocated into three different groups: Group 1 (control) received 0.9% NaCl, group 2, 0.25 mg kgp# ketamine and group 3, 0.5 mg kgp# ketamine, intravenously 1 minute prior to induction of anaesthesia, which was accomplished using a propofol target-controlled infusion system. The target propofol concentration was gradually increased until endotracheal intubation was possible and the target concentration at intubation was recorded. Heart rate, respiratory rate and noninvasive blood pressure were recorded immediately prior to induction, at successful intubation and at 3 and 5 minutes post-intubation. The quality of induction was graded according to the amount of muscle twitching and paddling observed. Data were analysed using a combination of chi-squared tests, Fisher's exact tests, Kruskal-Wallis, and anova with significance assumed at p < 0.05. There were no significant differences between groups in the blood propofol targets required to achieve endotracheal intubation, nor with respect to heart rate, noninvasive blood pressure or quality of induction. Compared with the other groups, the incidence of post-induction apnoea was significantly higher in group 3, but despite this dogs in this group had higher respiratory rates overall. Under the conditions of this study, ketamine does not seem to be a useful agent for co-induction of anaesthesia with propofol in dogs.