Enteral Feeding1

Enteral Feeding1

Laura E. Matarese

Michele M. Gottschlich

Metabolic hallmarks of trauma and surgery include hypermetabolism and erosion of protein stores. Provision of sufficient nutrition to the critically ill patient is vital to optimize conditions that advance recovery. Traditionally, nutrition was regarded as adjunctive care designed to stabilize the patient during repair. More recently, nutrition support has evolved as an emergent medical intervention specifically designed to attenuate the catabolic response to stress, prevent oxidative injury, protect the gastrointestinal (GI) mucosa, modulate the immune response, and promote wound healing. Current clinical practice guidelines strongly recommend enteral nutrition (EN) support for patients who cannot meet their nutrient needs through voluntary oral intake (for purposes of this chapter, EN refers primarily to tube feeding methods). This chapter provides guidelines for the use, implementation time and access substrate characteristics, diseases, specific formulations, and various administration tips that are important to consider during EN support.


Besides the GI tract’s role in digestion, absorption, and secretion, it is now recognized that the gut is a metabolically active organ that performs an important function in nutrient transport as well as immune defense. The deliberation on whether to use EN versus parenteral nutrition (PN) for feeding is largely academic because of the physiologic advantages associated with using normal digestive and absorptive pathways. In practice, if the GI tract is functional, accessible, and safe to use, EN should be given primary consideration with the mindset that intravenously supplied nutrients can be used as adjunctive support. Justification for directing nutrition support to the GI tract includes the fact that enteral nutrients experience first-pass metabolism in the liver, thus maximizing utilization. Furthermore, direct exposure of the small intestine to nutrition stimuli supports the functional integrity of the gut, enhances blood flow, and induces the release of endogenous trophic agents (e.g., cholecystokinin, gastrin, bombesin, and bile salts). Luminal nutrients help maintain normal intestinal pH and gut microbiota, whereas specific enteral nutrients (e.g., glutamine and short-chain fatty acids) provide a source of fuel for the intestine as well as stimulate enterocyte proliferation and growth. From a practical standpoint, enteral formulas mimic oral intake and supply intact nutrients such as fiber, whole proteins, dipeptides, and specialized fatty acids that cannot be delivered parenterally.

The positive effects of EN when compared with PN are well documented (Table 83.1) (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24). The most consistent beneficial outcome from the use of EN compared with PN is decreased infectious complications (3, 13, 14, 15, 16, 17). A decline in mortality has not been clearly demonstrated. EN has also been associated with significant reductions in hyperglycemia (11, 18), hospital length of stay (19, 20, 21, 22), and cost of nutrition intervention (11, 22, 23, 24).


The underlying metabolic responses to early enteral feeding and the benefit to clinical outcomes have been well described for the intensive care unit (ICU) patient (47). Secretory IgA, gut-associated lymphoid tissue (GALT), and mucosa-associated lymphoid tissue (MALT) are stimulated by enteral feedings and help fight infection locally in the gut and at distant sites as well (48, 49). An analysis of 12 randomized prospective controlled trials, showed significant reduction in infections and hospital length of stay with the use of immediate postoperative tube feeding or aggressive early oral nutrition versus standard therapy (50). A metaanalysis of 3 high-quality randomized controlled trials in trauma patients (total 126 patients) showed that the provision of early EN was associated with a significant reduction in mortality (odds ratio, 0.20; 95% confidence interval, 0.04 to 0.91) (51). Although GI motility is impaired in critically ill postoperative patients (52), the use of prokinetic agents alone or in combination with opiate antagonists and a multifaceted change in clinical practice (53, 54) aided the delivery of adequate EN support. EN and PN guidelines for critically ill patients have been published by the European Society of Parenteral and Enteral Nutrition (ESPEN) (55, 56) and the American Society for Parenteral and Enteral Nutrition (ASPEN) jointly with the Society of Critical Care Medicine (SCCM) (25). These guidelines make generally well-supported recommendations to initiate normal food intake or enteral feeding early and that EN is the preferred route of nutrition support over PN.

Current clinical practice guidelines suggest that tube feeding should generally be started within 24 hours after surgery for patients undergoing major head and neck surgery or major GI surgery for cancer, if possible (55, 56). In addition, it is recommended that EN should be initiated early in patients with severe trauma and in malnourished surgical patients (25, 55, 56). The presence of bowel sounds is not required to implement enteral feedings (see later). Current clinical practice guidelines (25, 55, 56) and several metaanalyses (50, 57) also favor the early institution of postoperative EN for surgical and acutely ill patients in the ICU setting without, however, uniformity of agreement (58, 59) or a clear definition of “early.” Ultimately, the decision to start early enteral intervention must be based not only on the aforementioned recommendations but also individualized based on each patient’s condition and special circumstances.

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Jul 27, 2016 | Posted by in PUBLIC HEALTH AND EPIDEMIOLOGY | Comments Off on Enteral Feeding1
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