Clinical Comparison of Tolerance to Elemental or Polymeric Enteral Feedings in the Postoperative Patient E. G. FORD, S. F. HULL, M. JENNINGS, R. J. ANDRASSY Journal of the American College of Nutrition 11:11–16, 1992

Controversy exists in the literature regarding the optimal enteral formula for use in the initial postoperative period: presently, clinicians use either an elemental formula because it is easiest to digest or a polymeric formula because it more closely approximates a normal diet. The authors of this study compared differences in gastrointestinal tolerance, nitrogen balance, and blood chemistry values in postoperative surgery patients randomly assigned to receive either an elemental diet (Vivonex TEN) or a polymeric diet (Osmolite HN). Thirty consecutive patients between the ages of 19 and 71 years undergoing abdominal operations with concomitant placement of a feeding jejunostomy were included in the study. Pancreatic cancer (n = 5) and gunshot wound to the abdomen (n = 4) were the two primary indications for surgery. The remaining patients had a variety of upper gastrointestinal, biliary, hepatic, and pancreatic disorders and intestinal perforation. Tube feeding was initiated with.5 kcal/mL at 50 mL/h on day 1, increasing to 75 mL/h on day 2 and to 1 kcal/mL at 75 mL/h on day 3. On day 4, the feedings were increased to the rate that was most appropriate to meet the patient's nutritional needs. Four patients in the Vivonex TEN group received supplemental parenteral nutrition for 3 to 7 days and three patients in the Osmolite HN group received parenteral nutrition for 1 to 5 days. Data collected for 7 days postoperatively included an initial nutrition assessment on the day of the operation (within 24 hours of laparotomy) that included serum albumin, prealbumin, sodium, potassium, blood urea nitrogen, and phosphate determinations. Additional data collected daily included 24‐hour urine urea nitrogen and creatinine determinations, fluid input and output, body weight measurements and tolerance to enteral feeding, ie, stool frequency (diarrhea was defined as ≥5 stools/ day), stool consistency, and incidence of abdominal discomfort. Serum electrolytes and prealbumin were measured on postoperative days 1, 4, and 7. Both study groups were similar with respect to sex, age, height, weight, diagnosis, type and duration of operation, energy needs, initial serum prealbumin levels, total lymphocyte count, and serum phosphate values. However, the mean initial serum albumin level was higher in the Osmolite HN group (3.39 ± 0.14 g/dL) than that of the Vivonex TEN group (2.97 ± 0.13 g/dL; p <.03). Urinary nitrogen and nitrogen balance were similar in the two groups and remained so throughout the study; serum prealbumin levels improved in both groups. Serum chloride significantly decreased in the Vivonex TEN group (from 105.7 ± 1.35 to 99.8 ± 1.24 mEq/L); this difference in serum chloride was attributed to the fact that Vivonex TEN has a lower chloride content than Osmolite HN (23 vs 40 mEq/L). Tube feeding tolerance was similar in both groups; there were no significant differences in stool frequency, although both feeding regimens caused watery stools (quantitative data not reported). When tube feeding intakes in the two groups were compared, no significant differences were seen on days 1 through 4, but on day 5, the Vivonex TEN group had a greater intake than did the Osmolite HN group (p <.02); however, when intake was expressed as percent of caloric goal, there was no difference between the groups at any time during the study. The authors concluded that there was no clinically significant difference in tolerance between the two enteral formulas in patients undergoing gastrointestinal surgical procedures who received early postoperative enteral feeding through a jejunostomy tube.