[[ International Symposium�F06 ]]

The Benefits/Risks of Enteral Nutrition: a Clinical and Scientific Approach Kenneth A. Kudsk, M. D. Professor of Surgery Director of Surgical Research The University of Tennessee, Memphis

Over the past ten years, there has been a significant interest in specific nutrients to up-regulate the immune system and improve host defense mechanisms. These nutrients include glutamine, arginine, omega-3 fatty acids, and nucleotides. It now appears that there is positive data in both cancer patients and in trauma patients that there is a significant reduction in septic complications when these immune-enhancing diets are used. In addition to septic complications, there also appears to be fewer wound healing complications as well as shorter length of stay. Most clinical trials have not compared these specialty diets, however, against isonitrogenous, isocaloric diets or diets with similar concentrations of fat. In a prospective, blinded study, 35 severely injured patients with an Abdominal Trauma Index 25 or an Injury Severity Score 21 who had early enteral access at the time of the initial surgery were randomized to either an immune-enhancing diet (Immun-Aid, n=17) or an isonitrogenous, isocaloric diet (Promote and Casec, n=18) diet. In addition, because of recent criticisms that nutrition studies do not include a nonfed control population, we prospectively analyzed--without randomization--the outcome of patients who were eligible by severity of injury but in whom enteral access had not been obtained (n=19). These patients served as contemporaneous controls. Outcome measurements included septic complications, antibiotic usage, hospital and ICU stay, and hospital cost. Two patients died in the treatment groups and were dropped from the study. There were no significant differences in ATI, Glasgow Coma Scale score, or ISS among the three groups (Table 1). There were, however, significantly more colon injuries in the control group, but the amount of blood administered to this group was significantly less than the two enterally fed groups. There was no significant difference in nitrogen intake between the two fed groups (0.230.2 g/kg/day for each group) and only two of the contemporaneous control group received any nutrition support prior to the onset of infectious complications. Patients randomized to the immune-enhancing diet developed significantly fewer major infectious complications (6%) than patients in the isonitrogenous group (infections = 41%, p=0.02) or the contemporaneous control group (58%, p=0.002). While there was no significant difference in prophylactic antibiotics or empiric antibiotics, significantly less therapeutic antibiotics were administered to the IED group than either the ISO or control group. While it did not quite reach statistical significance (p=0.08), the control group received therapeutic antibiotics for more than twice as long as the ISO group and five times as long as the IED group. Hospital stay was significantly shorter with the immune-enhancing diet and, while statistical significance was not reached, hospital charges were least with the IED, midrange with the ISO group, and highest in the unfed control patient population. It appeared that an immune-enhancing diet significantly reduced infectious complications in this randomized, blinded study of severely injured trauma patients compared with those receiving an isonitrogenous diet or no early enteral nutrition. Increased costs of these nutrients, however, should lead to their use in patients who are the most critically ill rather than as routine hospital diet for malnourished patients. There is compelling evidence that the gastrointestinal tract plays an important role in the reduction in infectious complications in critically injured patients. As we are unraveling mechanisms to explain the defects, hopefully, we will eventually be able to identify parenteral factors which will support these same defenses by and by administration to patients who require intravenous nutrition support. The increased cost of these nutrients, however, should lead to their use in patients who are most critically ill rather than as a routine hospital diet for malnourished patients. References: 1. Daly JM, Weintraub FN. Shou J. et al: Enteral nutrition during multimodality therapy in upper gastrointestinal cancer patients. Ann Surg 221 :327-38. 1995. 2. Kudsk KA, Minard G, Croce MA, Brown RO, Lowrey TS, Pritchard E, Dickerson RN, Fabian TC: A randomized trial of isonitrogenous enteral diets following severe trauma: an immune-enhancing diet (IED) reduces septic complications. Ann Surg 224(4):531-543, 1996.