Use of propofol for office-based anesthesia: effect of nitrous oxide on recovery profile

To evaluate the effect of nitrous oxide (N2O) on the recovery profile and the incidence of postoperative nausea and vomiting (PONV) after office-based surgery performed under propofol anesthesia.

Prospective, randomized, single-blind study.

Office-based surgical center.

69 ASA physical status I, II, and III healthy, consenting outpatients undergoing superficial surgical procedures lasting 15 to 45 minutes.

After a standard propofol induction (1.5 mg.kg-1 i.v.), anesthesia was initially maintained with propofol, 100 micrograms.kg-1.min-1 i.v., in combination with either air or N2O 65% in oxygen. The propofol infusion rate was subsequently varied to maintain an adequate depth of anesthesia. All patients received local anesthetic infiltration prior to the surgical incision, as well as during the operation. No prophylactic antiemetics were administered.

Recovery times and the incidences of PONV were recorded during the first 24 hours after surgery. Early and late recovery variables were similar in the two treatment groups; however, 65% N2O produced a 19% decrease in the propofol maintenance dosage requirement. One patient (3%) experienced nausea prior to discharge in the propofol-N2O group, and two patients (6%) experienced nausea at home in the propofol alone group. None of the patients vomited or received antiemetic medication during the 24 hours postdischarge period. Ninety-seven percent of patients receiving propofol alone and all of the patients in the propofol-N2O group were "very satisfied" with their anesthetic experience.

In outpatients undergoing office-based surgical procedures with propofol anesthesia, administration of 65% N2O decreased the anesthetic requirement without increasing PONV. Therefore, use of a propofol-N2O combination may be a cost-effective alternative to propofol alone for office-based anesthesia.