Comparison of the effects of different durations of propofol infusion on physical and biochemical values for long-term deep sedation in rabbits.

This study aimed to investigate the effects of prolonged propofol infusion for deep sedation on physiological, biochemical, and molecular parameters in rabbits. Rabbits were randomly assigned into four groups: control, and 6-, 12-, and 24-hour infusion groups. All animals were premedicated with xylazine HCl and induced with ketamine HCl. Propofol infusion was initiated at the 20th minute following induction. In all groups, propofol was administered at a dose of 50mg/kg/h during the first hour, followed by a gradual dose reduction depending on the duration of infusion. Throughout the infusion period, heart rate, respiratory rate, end-tidal carbon dioxide (EtCO₂), oxygen saturation (SpO₂), and body temperature were continuously monitored. Control animals were euthanized after induction, whereas animals in the infusion groups were euthanized at the end of their respective infusion periods. Blood samples were collected before the initiation of infusion and after its completion, and tissue samples were obtained post-mortem. With increasing infusion duration, time-dependent changes were observed in all physiological parameters except oxygen saturation (SpO₂). Biochemical analyses revealed that creatinine levels and BUN/CRE ratio did not differ significantly between groups. Molecular analyses demonstrated that all parameters, except catalase levels, varied significantly according to both tissue type and infusion duration. During the study period, no clinically significant pathological findings such as bradycardia, arrhythmia, or desaturation (<90%) were observed in rabbits subjected to 6-, 12-, and 24-hour propofol infusions. However, mechanical ventilation was required in four rabbits due to the development of apnea. These findings indicate that propofol infusion can be safely used for deep sedation in rabbits for durations up to 24hours.