Small Intestinal Motor Patterns in Critically Ill Patients After Major Abdominal Surgery J.-P.Tournadre, M.D.,M.Barclay, M.D.,R. Fraser, M.D.,J. Dent,M.D.,R. Young,M.D.,M.Berce, M.D., P. Jury,M.D.,L. Fergusson, M.D.,and J.Burnett, M.D. Department of Gastrointestinal Medicine and University Department of Medicine, Royal Adelaide Hospital; and Intensive Care Unit and Department of Vascular Surgery, Royal Adelaide Hospital and St. Andrews Hospital, Adelaide, Australia 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 pat- terning ofduodenal interdigestive motor activity isfre- quently abnormal after surgery or in patients who are crit- ically 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 postoperatively in critically ill patients in response to enteral feeding. METHODS: The effects of elective aortic aneurysm repair on smallintestinal motility were studied in 11 patients aged 63–77 yr.A 3.5-mm diameter multilumen extrusion was used to monitor pressures at 12 points, distributed between the antrum and 100 cm distal to the pylorus. An additional lumen allowed enteral feeding into the duodenum. Record- ings commenced immediately postoperatively and contin- ued for up to 4 days. Data are given as means and SEMs. RESULTS: Bursts (frequency . 10/min) of small intestinal pressure waves that resembled phase III interdigestive mo- tor activity occurred in all patients immediately after sur- gery.During mechanical ventilation, the timing of bursts along the segment evaluated was frequently abnormal for true interdigestive phase III activity, with simultaneous on- setin multiple channels (46%), multiple or distal origins (8%),or retrograde migration (20%). When patients were not being ventilated, the migration pattern of the bursts was more typical of interdigestive phase III activity. The interval between bursts was unusually short for interdigestive motor activity, although it increased from 30 6 12 min on day 1 to 41 6 18 min on day 3 (p , 0.05). A phase II pattern of pressure waves was virtually absent in all patients on all study days. In six patients who received postoperative en- teral nutrition, the bursts of pressure waves were not abol- ished by feeding, contrary to normal phase III activity. CONCLUSIONS: Smallintestinal pressure wave bursts are seen immediately after elective aortic aneurysm repair, but the migration of these bursts is frequently abnormal for phase III interdigestive activity. Duodenal nutrient delivery did not interrupt the occurrence of these bursts. Persistence of pressure wave bursts in this setting may be important in the delivery of enteral nutrition. (Am J Gastroenterol 2001; 96:2418 –2426. © 2001 by Am. Coll. of Gastroenterology) INTRODUCTION Reduced or absent intake ofnutrients contributes to im- paired immune function, and to serious infections during prolonged admission to the intensive care unit (ICU) after major surgery or trauma (1–3). Enteral feeding is associated with fewer complications than is parenteral nutrition, but is itself associated with serious complications such as aspira- tion pneumonia (4 – 6). Compared to nasogastric feeding, duodenal or jejunal tube feeding may have a lower risk of pulmonary aspiration (7) but higherratesof diarrhea, cramping abdominal pain, and distension (8). Limited data suggesthatthe upper smallintestinal motorresponse to nutrients is disordered in critically ill patients (9 –11), but there are no data on mid-to-distal smallintestinal motor function in this setting. It is possible that this incompletely documented abnormal patterning of small intestinal motor function may contribute to poor tolerance of enteral feeding Previous studies using perfused manometric assemblies have been of limited duration, in partbecause of the high volume of perfusate required to achieve adequate pressure rise rates with manometric channels of conventional diam- eters ranging from 0.6 to 0.8 mm in diameter (12).The number of sites from which pressures have been recorded has also been limited by the diameter of manometric assem blies or, in the case of intraluminal transducer recordings, the cost and technical feasibility of multiple (.8) recording point probes. Difficulties in placing such assemblies beyond the duodenum have also been a significant limiting factor. As a consequence, there are no studies which have exam- ined the relationship among gastric, duodenal, and jejunal motility during the first 72 h after major surgery. Recently miniature perfused manometric assemblies have been de- veloped that have manometric channels 0.36 – 0.50 mm in diameter, which are substantially smaller than more con- ventional manometric assemblies. Compared to standard- diameter manometric channels, miniaturization makes it THE AMERICAN JOURNAL OFGASTROENTEROLOGY Vol. 96,No.8, 2001 © 2001 by Am. Coll.of Gastroenterology ISSN 0002-9270/01/$20.00 Published by Elsevier Science Inc. PII S0002-9270(01)02514-X