Omission of nitrous oxide from a propofol-based anesthetic does not affectthe recovery of women undergoing outpatient gynecologic surgery

Background: Although nitrous oxide (N2O) is used commonly during anesthesia , clinically relevant advantages-disadvantages of using this agent are not well established in the ambulatory setting. This study in women undergoing ambulatory gynecologic surgery compares outcomes in patients administered t otal intravenous anesthesia with propofol versus the propofol plus N2O. The primary outcome was the time to home readiness. Secondary outcomes include d the incidence of postanesthetic adverse events. Methods: Women presenting for elective ambulatory termination of pregnancy or gynecologic laparoscopy were indued with an intravenous sleep dose of pr opofol and fentanyl. After induction, subjects were randomly allocated to m aintenance anesthesia with propofol alone or propofol plus 65% N2O. patient s were assessed by a blinded observer in the postanesthetic care unit at 20 -min intervals to determine home readiness. Postoperative pain and nausea w ere measured with visual analog scales. Postoperative analgesics and antiem etics were recorded. The incidence of adverse events occurring after hospit al discharge was assessed by a telephone interview 24 h postoperatively. Results: A total of 740 patients received propofol alone and 750 patients r eceived propofol plus N2O. Mean home readiness times were not significantly different between treatment groups. There were no significant differences between groups in pain scores, nausea scores, analgesia administration, or antiemetic administration before discharge. There were no significant diffe rences in the frequency of adverse events for 24 h after discharge from hos pital. Conclusions: Omission of N2O from a propofol-based anesthetic for ambulator y gynecologic surgery does not affect time to home readiness or the inciden ce of postoperative adverse events up to 24 h after discharge from hospital .