also predictive of the need for early nonelective readmission to the hospital (Friedmann et al., 1997; Sullivan, 1992).

The indications for providing nutrients by the enteral or parenteral route have not been well defined, and the efficacy of nutrition support is unproven in many circumstances. Nutrition support is most frequently used as short-term therapy for hospitalized patients with protein–energy undernutrition. The consequences of protein–energy undernutrition include depletion of body cell mass and decline of vital tissue and organ functions (see chapter 4). Compromise in host defense and wound-healing functions can result in suboptimal response to medical and surgical therapies. Complications may include hospital-acquired infections and wound breakdown. Adverse outcomes that may result include increased morbidity and mortality with associated increased length of hospital stay and increased use of health care resources (Friedmann et al., 1997; Incalzi et al., 1998; Jensen et al., 1997; Marinella and Markert, 1998; Sullivan et al., 1999).

The rationale for the provision of nutrition support includes (1) to mitigate the effects of semi-starvation, and (2) to favorably alter the natural history or response to treatment for a disease. Nutrition support is clearly indicated when food intake or nutrient assimilation will be compromised for an extended period, since starvation and death will otherwise result. Such patients may include those with inadequate gastrointestinal function (e.g., short-bowel syndrome or chronic intestinal obstruction), as well as those with severe oropharyngeal dysfunction or permanent neurological impairment.

Enteral and parenteral nutrition support of shorter duration can also prevent and treat protein–energy undernutrition among other selected Medicare beneficiaries in the hospital setting. Complications can be reduced among patients who are either undernourished or at high risk of becoming undernourished. Such patients may include those who have suffered major abdominal trauma or who undergo major elective abdominal surgery (Heyland, 1998; Kudsk et al., 1992; Moore et al., 1992; Müller et al., 1982; Senkal et al., 1997; VA TPN Cooperative Study Group, 1991). Reported benefits have included decreased rates of septic and wound complications, with resulting reductions in number of hospital days and cost.

There are also risks associated with enteral and parenteral nutrition support that must be taken into consideration. Serious complications include aspiration of enteral feedings and infectious and thrombotic events related to parenteral venous access (Cataldi-Betcher et al., 1983; Ryan et al., 1974). Appreciable under- or overfeeding can result in adverse metabolic consequences (Dark et al., 1985; Keys et al., 1950). Feeding intolerance, derangement of fluid balance, and laboratory abnormalities may be

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