Ventilation with nitrous oxide during open cholecystectomy increases the incidence of postoperative hypoxemia.

Abstract

The effect of intraoperative use of air versus nitrous oxide (N2O) on postoperative oxygen (O2) saturation in blood was evaluated in 40 ASA Class I and II patients undergoing elective, open cholecystectomy. Patients were allocated randomly to two groups on the basis of whether they received air (Group A, n = 20) or N2O (Group B, n = 20) intraoperatively. Oxygen saturation was recorded on arrival of the patients in the ward, 24 h, and 48 h postoperatively. Although mean O2 saturation did not differ significantly (P > 0.05) between the groups over the first 24 h postoperatively, it was significantly higher (P < 0.05) in Group A as compared to Group B 48 h postoperatively. Incidence of hypoxemia (O2 saturation < 90%) was 40% in Group B as compared to 0% in Group A at the end of 48 h postoperatively. We conclude that the use of N2O during cholecystectomy is associated with a higher incidence of hypoxemia postoperatively.