Comparison between anesthesia with sufentanil-midazolam and sevoflurane in medetomidine premedicated rabbits undergoing ovariohysterectomy

Abstract: Rabbits carry a high risk of anesthesia related death. This study was part of a project to develop a form of total intravenous anesthesia (TIVA) with minimal effects on cardiac, respiratory and metabolic parameters. In the study, TIVA with sufentanil and midazolam (group TIVA, n=9) was compared with inhalation anesthesia with sevoflurane (group SEVO, n=9) in female rabbits undergoing surgery (ovariehysterectomi). All rabbits were pre-medicated with medetomidin and carprofen before anesthesia induction. Anesthesia was induced with TIVA (2.3 μg/ ml sufentanil, 0.45 mg/ ml midazolam) at a rate of 4 ml/ kg/ h and the mean induction dose was 0.4 μg/ kg of sufentanil and 0.1mg/ kg of midazolam. The induction time was 4.7 ± 1.7 min (mean ± SD) and time to intubation 7.4 ± 6.7 min. After induction the TIVA infusion was maintained at rate of 0.6 ml/ kg/ h in group TIVA during preparations. In group SEVO, the TIVA infusion was stopped after anesthesia induction, and sevoflurane was administered at a concentration of 1 %. During surgery, the TIVA infusion rate and the sevoflurane concentration were adjusted to maintain a surgical plane of anesthesia in the respective groups. The mean infusion rate during anesthesia was 2.9 ± 1.5 ml /kg/ h in group TIVA and in group SEVO the mean sevoflurane concentration was 1.7 ± 1.0 % during maintenance of anesthesia. Mechanical ventilation was necessary in all rabbits in group TIVA and in four of the rabbits in group SEVO to maintain a PaCO2 between 5 and 6 kPa. Time to extubation was 19 ± 14 min in group TIVA, and time to recovery of the righting reflex was 56 ± 33 min. In group SEVO time to extubation was 5 ± 4 min and time to recovery of the righting reflex 21 ± 11 min. No differences between groups could be detected in terms of circulatory parameters.