Effects of propranolol on human postoperative ileus

BACKGROUND: The sympathetic nervous hyperactivity present in response to surgical stress has been implicated as an important component of the postoperative paralytic ileus. A randomized and prospective study was conducted, evaluating the effects of the preoperative beta-adrenergic blockade with propranolol in schistosomotic patients during the period of postoperative ileus. METHODS: The study compared schistosomotic patients submitted, or not, to beta-adrenergic blockade. Basal cardiac frequency was determined and propranolol was used in a dose of 40 mg twice a day. The dose was adjusted weekly until a minimum decrease of 20% in cardiac frequency was achieved. Three coupled bipolar electrodes were placed in the left colon in both groups, and registration of myoelectric activity of the left colon was made twice a day during the period of postoperative ileus using a system of data collection (DATA Q Series 200). The electric signals were previously amplified, filtered and separated into Electric Control Activity (ECA) and Electric Response Activity (ERA). RESULTS: The dose of propranolol varied from 80 to 160 mg/day. The proportional decrease in basal heart frequency varied from 20 to 33%, with an average of 25.4 +/- 3.9% in the propranolol group, maintaining a mean of 24.3 +/- 3.6% decrease in the postoperative period. Differences on clinical recovery of the postoperative ileus were not found. Significant differences on electromyographic patterns were not observed between the groups, except for the presence of a greater number of short-duration contractions in the second postoperative day in the beta-blocked group. CONCLUSION: The authors suggest that the preoperative beta-adrenergic blockade with propranolol does not determine myoelectric activity changes that could contribute to an earlier resolution of postoperative ileus.