General inhalation anesthesia or total intravenous associated with subarachnoid anesthesia in sheep

The purpose of this study was to evaluate the efficacy and safety of sheep submitted to inhalation anesthesia with isoflurane or total intravenous anesthesia with propofol, both associated with subarachnoid anesthesia. Fourteen animals were pre-medicated with 0.3mg.kg(-1) morphine IM, and 5 minutes later received 20mcg.kg(-1) detomidine IV. Then they were allocated into two groups: GISO (n=7), which were induced with 0.5mg.kg(-1) of diazepam and 5mg.kg(-1) of ketamine IV, and anesthesia maintenance was performed by isoflurane diluted in 100% oxygen; or GPRO (n=7), where animals were induced with 4mg.kg(-1) propofol IV and subsequent maintenance anesthesia with its own infusion of 0.3mg.kg.min(-1). To perform the bilateral tibial osteotomy, all animals received 0.5mg.kg(-1) 0.75% ropivacaine combined with 0.1mg.kg(-1) morphine by the intrathecal route. There was a 40% reduction in mean heart rate after the sedative protocol in both groups, resulting in a 23% average reduction until the end of the review. Mean arterial pressure showed transient elevation of around 16%, after induction of anesthesia in GISO, but reducing it to the end of the procedure, as well as in GPRO. The average EtISO was 0.57 V% and average infusion rate of propofol was 0.24mg.kg(-1).min(-1). The total time of surgery, anesthesia and extubation was 66 +/- 9.8, 92 +/- 7.0 and 13.8 +/- 1.5 minutes in GISO and 56 +/- 2.4, 82.9 +/- 4.6 and 5.4 +/- 1.5 minutes in GPRO. The maintenance of anesthesia with propofol or isoflurane produced similar anesthesia with minimal cardiovascular and blood gas effects, which are well tolerated in healthy sheep.