[Intestinal distention during elective abdominal surgery: should nitrous oxide be banished?]

High concentrations (70-80 per cent) of nitrous oxide (N2O) have been shown to cause distension of gas-containing distensible structures such as the intestines and are, for this reason, avoided by some during elective abdominal operations on the GI tract. We undertook this study to determine if N2O was responsible of a measurable change in intestinal diameter or of clinical difficulty in closing the abdomen in patients undergoing elective intestinal surgery of intermediate duration. Twenty patients scheduled for elective abdominal surgery were studied. Premedication and induction were identical in all patients. Maintenance of anesthesia in Group I was with enflurane in air/oxygen, and fentanyl. Patients in Group II received enflurane in N2O/oxygen, and fentanyl. FIO2 was 0.4 in both groups and monitored neuromuscular blockade with pancuronium was kept optimal throughout the operation. The surgeon was blinded as to the random distribution of patients to either group. Girth measurements at the level of the umbilicus were recorded before induction and after surgery. The circumferences of the terminal ileum and of the transverse colon were measured at the beginning and at the end of surgery. The surgeon was asked to rate the difficulty in closing the abdomen as 0 = none, 1 = slight, 2 = moderate, 3 = severe, 4 = impossible. Data were analysed using Student's paired t test, unpaired t test and Fisher's exact test. P less than 0.05 was considered statistically significant. There was no significant difference between groups in age, sex distribution, weight and duration of surgery (approximately 90 minutes in both groups).(ABSTRACT TRUNCATED AT 250 WORDS)