THE INFLUENCE OF NITROUS-OXIDE ON RECOVERY OF BOWEL FUNCTION AFTER ABDOMINAL HYSTERECTOMY

The influence of nitrous oxide on the recovery of bowel function was studied in 36 patients anaesthetised for elective abdominal hysterectomy with or without salpingooophorectomy. Patients were randomly assigned to receive either isoflurane in nitrous oxide and 30% oxygen (N2O group) or isoflurane in air and 30% oxygen (Air group). Anaesthetic management included thiopentone, fentanyl, suxamethonium and atracurium. The lungs were not ventilated prior to intubation. Before closing the abdomen, the surgeon assessed the degree of distension of the intestines and the closing conditions. Postoperative nausea and vomiting was assessed 2, 6, 12 and 24 h after recovery from anaesthesia. The lapse of time before mobilisation and passing of flatus and faeces was recorded. The patients in the Air group were significantly older than the patients in the N2O group (48.9 years versus 44.0 years, P = 0.04); otherwise, there were no differences in the demographic data of the patients. We found no significant differences between the groups with respect to nausea and vomiting, distension of the intestines before closure of the abdomen, closing conditions, time elapsing before mobilisation, constipation before recovery of bowel function or time elapsing before passing of flatus. We found a statistically significant delay of 10.3 h in time elapsing before passing of faeces in the N2O group compared to the Air group (P = 0.04), suggesting a potentially adverse effect of nitrous oxide. However, the delay seen in the present study is of dubious clinical significance. In conclusion, regarding operating conditions and time elapsing before recovery of bowel function, our results do not justify the omission of nitrous oxide from anaesthetics lasting approximately 2 h or less.