Effects of enteral nutrition on gastrointestinal function in patients who are critically ill.

Nutritional management is a cornerstone of therapy for patients who are critically ill. Data show that enteral nutrition is better than parenteral nutrition with regard to the morbidity of critcally ill patients, especially for infectious complications. These findings suggest that feeding patients enterally has other beneficial effects besides delivering nutrients. In the absence of enteral nutrition, the mucosal architecture changes distinctly, leading to an impairment in function of the gastrointestinal barrier. This impairment facilitates the migration of bacteria from the intestinal lumen into the submucosal tissue and triggers epithelial inflammation. Consequently, proinflammatory and anti-inflammatory factors are imbalanced, leading to further degradation of gastrointestinal mucosal resistance. The enteral stimulus is also important to maintain physiological interaction of commensal bacteria with enteric immune cells. The absence of enteral nutrition induces deregulation of receptors that modulate the immunological response to commensal bacteria and pathogens-an important factor that initiates intestinal inflammation. Additionally, without enteral nutrients, the gastrointestinal mucosa atrophies because epithelial cells absorb nutrients directly from the gastrointestinal tract to meet their nutritional requirements. All these negative effects of absent enteral nutrition can be explained by a distinct change in cellular signalling pathways. Studies show that the physiological stimulus of enteral nutrition is crucial to maintain gastrointestinal functions such as barrier, immunological, and resorptive function. Enteral nutrients are important to maintain intact gastrointestinal motility since the nutrients stimulate the secretion of motility-regulating gastrointestinal hormones.