Comparison of anesthesia induced by ketamine-fentanyl combination and maintained by propofol or etomidate in New Zealand white rabbits.

Ketamine-fentanyl-propofol and ketamine-fentanyl-etomidate combinations were administered intravenously to four groups of rabbits. Each group received ketamine (30 mg/kg of body weight) and fentanyl (0.025 mg/kg) for anesthesia induction. Either propofol or etomidate was administered by an infusion pump to maintain anesthesia. The rabbit's responses to noxious stimuli were determined before anesthesia was induced and at 10-min intervals thereafter until the rabbit recovered. The effects of the anesthetic combinations on the cardiopulmonary system were measured by monitoring respiratory and heart rates, blood pressure, and arterial blood gas tensions. Etomidate infused at the rate of 0.2 or 0.1 mg/kg/min could maintain surgical anesthesia with fewer effects on the cardiopulmonary system for 40 and 30 min respectively. However, the high mortality and side effects such as hemolysis in these two groups preclude the clinical use of etomidate for anesthesia maintenance. Propofol administered intravenously at rates of 0.8 and 0.4 mg/kg/min could maintain surgical anesthesia for 40 and 30 min respectively. However, relatively severe hypotension, hypercapnia, and respiratory acidosis were associated with this drug. Recovery from the propofol infusion was very rapid. Ketamine-fentanyl-etomidate combination is not recommended for clinical anesthesia in rabbits. Ketamine-fentanyl-propofol combination at a dosage of 30-0.025-0.4 mg/kg/min can be safely used for short-term surgery.