Enteral nutrition in patients with pancreatitis

Clinical study on nutrition support in patients with severe acute pancreatitis

AIM: To investigate the effect of nutritional support therapy on severe acute pancreatitis (SAP).

METHODS: A total of 96 patients with severe acute pancreatitis were divided randomly into control and treatment groups. The former group received total parenteral nutrition (TPN) via central venous infusion, while parenteral nutrition (PN) and enteral nutrition (EN) therapies were applied in different phases for the latter group. The nutrition status, acute phase responses, pancreas lesions, enteric mucosa penetrability and immune functions were monitored.

RESULTS: Body weight and prealbumin concentration were increased in treatment group, compared to those in the control group, but albumin concentration did not change significantly. Acute physiology and chronic health evaluation II (APACHE II) scores decreased after 7 d of treatment, whereas the scores of the control group decreased on the 11^th day. Concentrations of tumor necrosis factor-α (TNF-α), interleukine-6 (IL-6) and serum C reactive protein (CRP) dropped earlier in the treatment group (on the 4^th day) than that in the control group (on the 7^th day). No difference was observed in pancreatic lesions between the control and treatment groups. Concentration of endotoxin and lactulose/manicol (L:M) ratio of urine did not change in treatment group, but those in the control group were elevated markedly. Compared with the treatment group, CD4:CD8 T cells ratio and immunoglobulin G (IgG) concentration in the control group decreased significantly.

CONCLUSION: Compared to TPN, the combined therapy of EN and PN could improve the nutrition status and moderate the acute phase response obviously. Moreover, the integrity of enteric mucosa and immune function were protected more effectively in treatment group than in the control one. On the other hand, EN did not simulate the excretion of pancreas and avoid exaggerating the inflammation of pancreas. Thus, appropriate application of PN and EN appears to be more effective for patients with SAP.

Nutrition support during acute pancreatitis

Studies have shown that protein catabolism increases by 80% and energy expenditure by 20% in acute pancreatitis, indicating that nutritional requirements are elevated. Other studies have associated the resolution of negative nitrogen balance by nutrition support with improved outcome. Consequently, the need for effective nutrition is one cornerstone of management of acute pancreatitis. Concerns that feeding may exacerbate the disease process by stimulating the synthesis of proteolytic enzymes in the acinar cell and perpetuating autolysis has led to the widespread use of total parenteral nutrition (TPN) and bowel rest. Unfortunately, the use of TPN in clinical practice has been associated with major metabolic and infective complications, possibly because 1). patients with acute pancreatitis are intolerant of glucose due to coexistent pancreatic endocrine dysfunction and 2). the disease causes immune suppression. This has led to the search for alternatives. Based on physiologic studies, infusion of nutrients into the distal jejunum bypasses the stimulatory effect of feeding on pancreatic secretion. Many controlled trials have compared TPN with jejunal feeding. No study has shown that jejunal feeding exacerbates the disease. Further, jejunal feeding is associated with fewer infectious and metabolic complications. These observations and the fact that enteral feeding is one-tenth the cost of TPN has resulted in the general acceptance of jejunal feeding as the preferred mode for maintaining nutrition in patients with acute pancreatitis.

Nutrition in acute pancreatitis

The majority of patients (80%) admitted with acute pancreatitis recovers after a few days of bowel rest and intravenous fluids. However, some cases progress to a fulminant disease complicated by a severe systemic inflammatory response and multiple organ failure, a condition in which mortality is related to the degree of negative nitrogen balance. The goal of nutrition support in this situation is to cover the increased metabolic demands without stimulating pancreatic secretion and exacerbating the "autodigestion" that characterizes the condition. Although human and animal studies have shown conflicting results regarding the effect of composition and location of feeding on pancreatic enzyme secretion, there is consensus that total parenteral nutrition (TPN), given at moderate infusion rates, does not significantly stimulate secretion in humans and that enteral diets stimulate enzyme secretion unless delivered below the jejunum. Consequently, until recently TPN has been the standard of therapy. The fact that the cost and complications of TPN can often outweigh its benefits (catheter sepsis, hyperglycemia) has led to a series of recent controlled clinical trials of modified enteral diets in which the diet is delivered by nasojejunal tube. Results have demonstrated that enteral nutrition, with either elemental or polymeric formulas, was cheaper, safer, and at the same time more effective in reducing the systemic inflammatory response. The pathophysiologic explanation for these observations needs further investigation.