Small intestinal motor patterns in critically ill patients after major abdominal surgery

OBJECTIVES: In patients who have had major surgery or trauma. early enteral feeding is safer and more effective than parenteral or nasogastric feeding but is frequently associated with diarrhea. Limited recordings have shown that the patterning of duodenal interdigestive motor activity is frequently abnormal after surgery or in patients who are critically ill. The aims of this study were to evaluate the effects of major abdominal surgery on small intestinal motility, and to elucidate the motor patterns that occur postop eratively in critically ill patients in response to enteral feeding. METHODS: The effects of elective aortic aneurysm repair on small intestinal motility were studied in I I patients aged 63-77 yr. A 3.5-mm diameter mul tilumen extrusion was used to monitor pressures at 12 points, distributed b etween the antrum and 100 cm distal to the pylorus. An additional lumen all owed enteral feeding into the duodenum. Recordings commenced immediately po stoperatively and continued for up to 4 days. Data are given as means and S EMs. RESULTS: Bursts (frequency > 10/min) of small intestinal pressure waves tha t resembled phase Ill interdigestive motor activity occurred in all patient s immediately after surgery. During mechanical ventilation, the timing of b ursts along the segment evaluated was frequently abnormal for true interdig estive phase Ill activity, with simultaneous onset in multiple channels (46 %), multiple or distal origins (8%), or retrograde migration (20%). When pa tients were not being ventilated, the migration pattern of the bursts was m ore typical of interdigestive phase Ill activity. The interval between burs ts was unusually short for interdigestive motor activity, although it incre ased from 30 +/- 12 min on day I to 41 +/- 18 min on day 3 (P < 0.05). A ph ase Il pattern of pressure waves was virtually absent in all patients on al l study days. In six patients who received postoperative enteral nutrition. the bursts of pressure waves were not abolished by feeding, contrary to no rmal phase Ill activity. CONCLUSIONS: Small intestinal pressure wave bursts are seen immediately aft er elective aortic aneurysm repair, but the migration of these bursts is fr equently abnormal for phase Ill interdigestive activity. Duodenal nutrient delivery did not interrupt the occurrence of these bursts. Persistence of p ressure wave bursts in this setting may be important in the delivery of ent eral nutrition.