The electability and the standardization of anaesthetic doses of ketamine and propofol in dogs by a gravimetric method.

Abstract

Inhalation anaesthetic agents have been used worldwide for anaesthesia in animals with improving safety and efficacy, but these agents are expensive, difficult or impossible to use for bronchoscopies and laryngoscopies, more over, these may couse organ toxicity, have an operating theatre pollution on personnel, and possible environmental damage caused by nitrous oxide and the halogenated volatile anaesthetics. A suitable alternative methode to compare with and reduce those side effects of inhalation anaesthesia agents is needed. The aim of this study was to evaluate quality of anaesthesia by gravimetric infusion anaesthesia with ketamine HCl and propofol to get a standard dose of ketamine HCl and propofol in dogs. The quality of anaesthesia, duration of actions, and the physiological response of anaesthesia were evaluated in two steps of the study. In the first step, twenty four male domestic dogs were used in this experiment and divided randomly into six groups. In the second step, twenty male domestic dogs were used and divided randomly into five groups. In the first step, group 1, group 2, and group 3 were preanaestheted intramuscularly with 0.03 mg/kg BW atropine and 2 mg/kgBW xylazine respectively. Group 4 to 6 received in the same way 0.03 mg/kgBW atropine and 0.2 mg/kgBW midazolam respectively. Group 1 and 4 were induced then with 4 mg/kgBW ketamine HCl, group 2 and 5 with 4 mg/kgBW propofol, and group 3 and 6 were induced with a combination dose of 4 mg/kgBW ketamine HCl and propofol respectively. The quality of anaesthesia, duration of action and the physiological responses were evaluated. From the first step, group 3 was elected the best premedication for the second step. In the second step, all group received 0.03 mg/kgBW atropine sulfate and 2 mg/kgBW xylazine intramuscularly and were then induced intravenously with 4 mg/kgBW Ketamine HCl and propofol respectively. Following the anaesthesia, group I, II, III in second step received intravenous infusion of mixed ketamine HCl and propofol in saline by a gravimetric method to maintain the anaesthesia status. The doses of mixture were arranged at the rate of 0.2, 0.4, and 0.6 mg/kgBW/ minute respectively. Group IV was only infused with 0.4mg/kgBW/minute propofol in saline and compared to the inhalation anaesthesia, and group V was given isoflurane of 1.0 – 2.0 %. The quality of anaesthesia, duration of action, heart rate (HR), capillary refill time (CRT), noninvasive blood pressure (NIBP), electrocardiogram (ECG), respiratory rate (RR), blood oxygen saturation (SpO2), end tidal CO2 (ET CO2), and rectal temperature (RT) were measured. All groups showed rapid and smooth inductions, prolonged surgical stage, and rapid recovery. Animals of groups I and II yielded minimal physiological effects. The HR, RR, ET CO2, SpO2, CRT, NIBP, RT, and ECG wave were relatively stable. The combination of group III showed SpO2 depression, and an increase in instability of HR, RR and ET CO2. Group IV showed a decrease in HR, SpO2 and respiratory depression. All combinations showed no significant influence (P>0,05) on the electrocardiogram. The combination of ketamine HCl-propofol at the dose rates of 0.2 and 0.4 mg/kgBW/minute was an ideal dose of gravimetric method of infusion.