Anestesia intravenosa contínua com tiletamina-zolazepam.

Abstract

The objective was to evaluate the quality of continuous intravenous anesthesia promoted by the tiletamine-zolazepam combination, in rabbits and bitches pre-medicated with acepromazine. Six rabbits and eight bitches weighing 2.5±0.3 and 13.7±1.9 kg, respectively, were used. The animals were premedicated with acepromazine (0.1 mg/kg) and, after 15 minutes, intravenous induction of 2 mg/kg bolus of the tiletamine-zolazepam combination, followed by continuous intravenous infusion of these drugs at a dose of 10 mg/kg/h (rabbits) and 2 mg/kg/h (bitches), for 60 minutes. The parameters that were measured in all animals, before pre-medication (M-15), before induction (M0) and at 5, 10, 20, 30, 40, 50 and 60 minutes after the continuous infusion (M5, M10, M20, M30, M40, M50 and M60) were as follows: electrocardiography (ECG), heart rate (HR), mean arterial pressure (MAP), respiratory rate (RR) and body temperature (BT), rabbits were still measured 90 minutes after infusion (M90). Arterial hemogasometry was performed at moments M-15, M0, M5, M30, M60 and M90 in rabbits, and at moments M-15, M0, M30 and M60 in bitches. An electrical stimulator was used to evaluate the degree of analgesia. We also evaluated the myorelaxation and the quality of the anesthetic recovery, classifying these parameters as: excellent, good and bad. The anesthetic recovery time was recorded in minutes. Rabbits: MAP decreased significantly after M-15. RR decreased significantly in M20, M30 and M50. Hypothermia did not occur. There was no significant difference regarding the electrocardiographic parameters, HR, PaCO2, HCO3 -, TCO2, EB and analgesia. PaO2 and SaO2 in M5 were lower than in M-15, but without occurrence of hypoxemia. The myorelaxation and the quality of the anesthetic recovery were considered excellent. The recovery period was 69.3 ± 19.3 minutes. Bitches: HR increased significantly at time M10 in relation to M-15, and at moments M5, M10, M40 and M50 in relation to M0. MAP decreased significantly in M20 and M30 compared to baseline. BT decreased significantly in M50 compared to M0, but no hypothermia was observed. RR showed a significant reduction at moments M5, M10 and M20 in relation to M- 15, and in M5 and M10 in relation to M0, and bradypnoea was observed during the first 20 minutes after anesthetic induction. Significant decreases in the PR interval at moments M10, M40 and M50 were observed in relation to M-15. The R wave amplitude showed a significant decrease in M20 compared to M-15. In the other ECG parameters, there was no significant difference between the moments evaluated. Hemogasometric parameters and analgesia did not present significant alterations. The myorelaxation and the quality of the anesthetic recovery were considered excellent. The recovery period was 15.1±7.7 and 45.5±23.1 minutes. Continuous intravenous administration of tiletamine-zolazepam in rabbits and bitches premedicated with acepromazine promoted intense myorelaxation and excellent anesthetic recovery, however, in rabbits, it produced hypotension, transient hypoxemia and mild analgesia, and in bitches it produced transient respiratory depression and moderate analgesia.