RECOVERY CHARACTERISTICS OF PROPOFOL ANESTHESIA, WITH AND WITHOUT NITROUS-OXIDE - A COMPARISON WITH HALOTHANE NITROUS-OXIDE ANESTHESIA IN CHILDREN

Few studies have examined whether nitrous oxide influences the recover y characteristics of propofol anaesthesia. The present study examined the effect of nitrous oxide on the recovery characteristics of propofo l anaesthesia, and compared these data with those for halothane/nitrou s oxide anaesthesia. Sixty children aged 3-12 years were assigned at r andom to receive one of three maintenance regimens: propofol with or w ithout nitrous oxide (70%) or halothane/nitrous oxide (70%). During pr opofol/N2O anaesthesia, the infusion rate of propofol (180 +/- 39 mu g .kg(-1).min(-1)) required to maintain the mean arterial pressure and h eart rate within 20% of the baseline values was significantly less tha n that during propofol/O-2 (220 +/- 37 mu g.kg(-1).min(-1); P<0.005). The time from discontinuation of anaesthesia to eye-opening (11 +/- 6 min), to response to commands (12 +/- 6 min), and to return of full wa kefulness (21 +/- 10 min) after propofol/N2O were similar to those aft er propofol/O-2, but significantly less (by approximately 30%) than th ose after halothane (P<0.05). The overall incidence of emesis after pr opofol/N2O (53%) was greater than that after propofol/O-2 (17%, P<0.05 ) and comparable to that after halothane/N2O (58%). These data suggest that N2O has little effect on the rate of recovery after propofol, bu t significantly increases the incidence of postoperative emesis, there by attenuating one of the main attributes of propofol anaesthesia.