Intraoperative ventilation with air and oxygen during laparoscopic cholecystectomy decreases the degree of postoperative hypoxaemia

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, 24 h and 48 h after surgery while breathing room air. The mean PaO2 24 h and 48 h postoperatively decreased significantly in both groups compared with the preoperative values. The mean PaO2 24 h 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 PaO2 48 h 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 PaCO2 did not show any significant change during 48 h 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.