Background: Failure to use the gastrointestinal (GI) tract in patients with acute pancreatitis may exacerbate the stress response and disease severity, leading to greater incidence of complications and prolonged hospitalization. The objectives of this study were to determine the optimum route for nutrition support, whether nutrition therapy is better than no artificial nutrition support, whether specific additives to enteral or parenteral therapy can further enhance their efficacy, and whether methodologic differences irk delivery of enteral nutrition (EN) influence tolerance. Methods: A computerized search was performed of MEDLINE, Cochrane database, EMBASE, and reference lists of pertinent review articles for prospective randomized trials in adult patients with acute pancreatitis that evaluated interventions with nutrition therapy. Primary outcome data and surrogate endpoint parameters (for nutrition indices, stress markers, and measures of the inflammatory/immune response) were extracted in duplicate independently. Where appropriate, meta-analysis was performed by random-effects model. Results: From 119 articles screened, 27 randomized controlled trials were included and analyzed. In patients admitted for acute pancreatitis, meta-analysis of 7 trials showed that use of EN was associated with a significant reduction in infectious morbidity (risk ratio [RR] = 0.46; 95% confidence interval [CI], 0.29-0.74; p =.001) and hospital length of stay (LOS; weighted mean difference [WMD] = - 3.94; 95% Cl, - 5.86 to - 2.02; p <.000 1), a trend toward reduced organ failure (RR = 0.59; 95% Cl, 0.28-1.27; p =.18), with no effect on mortality (RR = 0.88; 95% Cl, 0.43-1.79; p =.72) when compared with use of parenteral nutrition (PN). Results from individual studies suggest that EN in comparison to PN reduces oxidative stress, hastens resolution of the disease process, and costs less. Insufficient data exist to determine whether EN improves outcome over standard therapy (no artificial nutrition support) in patients admitted for acute pancreatitis. However, in those patients requiring surgery for complications of acute pancreatitis, meta-analysis of 2 trials indicates that provision of EN postoperatively may reduce mortality (RR = 0.26; 95% Cl, 0.06-1.09; p =.06) compared with standard therapy. PN provided early within 24 hours of admission was shown to worsen outcome, whereas PN provided later after full-volume resuscitation appeared to improve outcome when compared with standard therapy. In early individual studies, specific supplements added to EN, such as arginine, glutamine, omega-3 polyunsaturated fatty acids, and probiotics, may be associated with a positive impact on patient outcome in acute pancreatitis, compared with EN alone without the supplements, but studies are too few to make strong treatment recommendations. Supplementation of PN with parenteral glutamine was shown to reduce oxidative stress and improve patient outcome (reduced duration of nutrition therapy and decreased hospital LOS) compared with PN alone in patients with acute pancreatis. A wide range of tolerance to EN exists, irrespective of known influences such as mode (continuous vs bolus) and level of infusion within the GI tract (gastric vs postpyloric). Conclusions: Patients with acute severe pancreatitis should begin EN early because such therapy modulates the stress response, promotes more rapid resolution of the disease process, and results in better outcome. In this sense, EN is the preferred route and has eclipsed PN as the new "gold standard" of nutrition therapy. Wen PN is used, it should be initiated after 5 days. The favorable effect of both EN and PN on patient outcome may be further enhanced by supplementation with modulators of inflammation and systemic immunity. Individual variability allows for a wide range of tolerance to EN, even in severe pancreatitis.
