Intraoperative Ventilation with Air and Oxygen during Laparoscopic Cholecystectomy Decreases the Degree of Postoperative Hypoxaemia

Abstract

We studied the effects of intraoperative use of air in oxygen (O₂) (FiO₂ = 0.33) versus nitrous oxide (N₂O) in O₂ (FiO₂ = 0.33) on the degree of postoperative hypoxaemia in 30 patients undergoing laparoscopic cholecystectomy. Patients were randomly allocated to receive either general anaesthesia with air (Group A, n=15) or with N₂O (Group N, n=15). Arterial gas tensions were measured before, 24h and 48h after surgery while breathing room air. The mean P_aO₂ 24h and 48h postoperatively decreased significantly in both groups compared with the preoperative values. The mean P_aO₂ 24h postoperatively in Group N (74.6±6.4 mmHg) tended to be lower than that in Group A (78.1±8.3 mmHg). The mean P_aO₂ 48h postoperatively in Group N (75.0± 7.8 mmHg) was significantly lower than that in Group A (83.5±7.9 mmHg) (P<0.05). On the contrary, the mean P_aCO₂ did not show any significant change during 48h postoperatively in either group. Our results suggest that ventilation with N₂O and O₂ during laparoscopic cholecystectomy is associated with a lower degree of postoperative hypoxaemia.