[Propofol in continuous perfusion as anesthetic in experimental surgery in the rabbit]

To study anesthesia with intramuscular ketamine chlorohydrate and continuous intravenous perfusion of propofol (2.6 phenyl diisopropyl) in 30 white New Zealand rabbits undergoing tracheal and vascular surgery and experimental bronchoscopy without mechanical ventilation.

The animals were monitored by transcutaneous pulse oximetry and were sedated before canalization of the auricular vein. Oxygen was administered under a bell at a rate of 5 l/min. Variables recorded were heart and respiratory rates, oxygen saturation, blink reflex, and movements during surgery. The anesthetic protocol consisted of sedation (intramuscular ketamine chlorohydrate 50 mg/kg), followed by induction (intravenous propofol 3 mg/kg), and maintenance with intravenous infusion of diluted propofol in 2 phases as follows: a loading dose of 1.2 mg/kg/min first, followed by maintenance with 0.9 mg/kg/min propofol in dextrose at 5% concentration (4 mg/ml).

The procedure afforded adequate anesthesia for surgery lasting up to 70 min. Vital signs were stable in all animals. The perfusion rate was modified during surgery in 8 animals, in 5 because of superficial anesthesia and in 3 because of respiratory depression. Respiratory rate was the only parameter that was significantly correlated with depth of anesthesia and propofol dose. Postanesthetic recovery was rapid in all animals. No cases of heart/respiratory failure or death occurred.

The proposed method is useful for anesthetizing the rabbit, as it renders mechanical ventilation unnecessary. Only simple monitoring of respiratory rate is required.