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 total intravenous anesthesia with propofol versus the propofol plus N2O. The primary outcome was the time to home readiness. Secondary outcomes included the incidence of postanesthetic adverse events.
Methods: Women presenting for elective ambulatory termination of pregnancy or gynecologic laparoscopy were induced with an intravenous sleep dose of propofol and fentanyl. After induction, subjects were randomly allocated to maintenance anesthesia with propofol alone or propofol plus 65% N2O. Patients were assessed by a blinded observer in the postanesthetic care unit at 20-min intervals to determine home readiness. Postoperative pain and nausea were measured with visual analog scales. Postoperative analgesics and antiemetics were recorded. The incidence of adverse events occurring after hospital discharge was assessed by a telephone interview 24 h postoperatively.
Results: A total of 740 patients received propofol alone, and 750 patients received 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 differences in the frequency of adverse events for 24 h after discharge from hospital.
Conclusions: Omission of N2O from a propofol-based anesthetic for ambulatory gynecologic surgery does not affect time to home readiness or the incidence of postoperative adverse events up to 24 h after discharge from hospital. (Key words: Awareness; outpatient surgery; total intravenous anesthesia.)