Nitrous Oxide, Nausea, and Vomiting After Outpatient Gynecologic Surgery

Postanesthetic nausea and vomiting can delay discharge of outpatients and can cause occasional admissions to hospital. Nitrous oxide (N2O) has been thought to increase this frequency, but previous studies have been indecisive. One hundred eighty-five unpremedicated outpatients undergoing laparoscopic tubal ligation were studied to determine the effect of N2O on postanesthetic nausea and vomiting. The patients were divided by registration number, intubated, and given mixtures of either N2O-O2 enflurane or air-O2 enflurane. Intravenous (IV) lidocaine, administered initially prior to intubation to control bucking, was later omitted in randomly chosen cases to determine its effect. The overall prevalence of nausea and vomiting was 29.2% with N2O and 9.3% with air (p less than 0.001). While the lidocaine subseries was small, it appeared to prevent nausea and vomiting, particularly when N2O was omitted. Further study is justified. Fentanyl, given postoperatively for pain, did not increase the prevalence of nausea and vomiting. It was concluded that N2O is associated with an increased prevalence of nausea and vomiting.