Recovery of bowel motility after high dose fentanyl or morphine anaesthesia for cardiac surgery

Recovery of bowel function was investigated after cardiac surgery. The time to first passage of flatus was measured using a carbon dioxide analyser as an indication of the return of coordinated bowel motility in 22 adult patients who received high-dose fentanyl (56.3, SD 20.9 micrograms/kg) or morphine (1.3, SD 0.7 mg/kg) anaesthesia. The time from the patient's arrival in the intensive care unit to passage of the first flatus in patients who received fentanyl anaesthesia was significantly longer than in those who received morphine (p less than 0.05). There was a significant relationship between the time to first flatus and the total dose of fentanyl, but no such relationship could be demonstrated for morphine. It is concluded that high-dose fentanyl anaesthesia delays recovery of bowel motility in a dose-dependent manner.