Propofol modifies recovery from isoflurane-nitrous oxide anesthesia

A randomized, prospective study was performed to evaluate the hemodynamic changes and recovery characteristics in 60 ASA physical status class I-II unpremedicated patients undergoing gynecological laparotomies with either isoflurane anesthesia only (ISO group) or isoflurane anesthesia followed by propofol infusion (ISO-PRO group). All patients received isoflurane 0.5-1.5% and nitrous oxide (N2O) 66% in oxygen after tracheal intubation. ISO-PRO group (n = 30) received 6 mg kg-1 hr-1 propofol infusion in substitution for isoflurane 25 minutes before the end of surgery. Propofol in ISO-PRO group and isoflurane in ISO group (n = 30) were discontinued 5 minutes before the end of surgery. In both groups, N2O was administered throughout the operation until skin was closed. Hemodynamic measurements were similar between the two groups except at extubation when heart rate and blood pressure were lower in ISO-PRO group. The maximal blood pressure was also lower in ISO-PRO group. In ISO-PRO group, the time required to responsiveness to verbal commands and to orientation were significantly shorter. ISO-PRO group had better Steward's score on arrival at the recovery room and was earlier to get a full score of six. The two groups experienced similar rates of emesis and excitement either two hours or 24 hours postoperatively. We conclude that in relatively long intra-abdominal operations, replacement of isoflurane by propofol infusion 25 minutes before the end of surgery may provide stable maintenance of anesthesia and a faster recovery.