Specialized Nutrition Support

SPECIALIZED NUTRITION SUPPORT

Specialized nutrition support is the provision of nutrients orally, enterally, or parenterally with therapeutic intent (1). Enteral nutrition involves the nonvolitional delivery of nutrients by tube into the gastrointestinal tract through a feeding tube, catheter, or stoma (1,2). Parenteral nutrition is the administration of nutrients intravenously (1,2). The provision of specialized nutrition support via the enteral (gastrointestinal) or parenteral (intravenous) routes may help maintain the nutritional status of patients unable to consume adequate nutrients by mouth during their recovery from illness. The modality of nutrition support selected should permit the delivery of required nutrients by the safest, most cost-effective route for the patient. Enteral nutrition is the preferred route for the provision of nutrition for patients who cannot meet their needs thorough voluntary oral intake (2). The goals of nutrition support in both well-nourished and malnourished critically ill patients are to prevent the depletion of lean body mass, promote acute phase and whole body protein synthesis, and prevent physiologic deterioration (3).

The following section is a brief outline of nutritional management with these two modalities of nutritional support. For more detailed information, the clinician is directed to the referred literature and published guidelines related to the management of critically ill patients in the intensive care setting (3).

Indications (1)
The 2006 evidence-based guidelines for managing critical care patients in the intensive care unit support early nutrition intervention. In the critically ill patient, enteral nutrition is recommended over parenteral nutrition when the patient is hemodynamically stable and has a functioning gastrointestinal tract; enteral nutrition along with adequate fluid resuscitation should be initiated 24 to 48 hours after injury or admission to the intensive care unit (Grade I)* (3). In the critically ill patient, early enteral nutrition is associated with a reduction in infectious complications (Grade I) (3) and may reduce the length of hospital stay (3). Patients who receive enteral nutrition experience lower rates of septic morbidity and fewer infectious complications than patients who receive parenteral nutrition (Grade I) (3,4).

Guidelines from the American Society of Parenteral and Enteral Nutrition suggest that specialized nutrition support be initiated in patients with inadequate oral intake for 7 to 14 days and in patients expected to have inadequate oral intake for 7 to 14 days (1). Moderately or severely malnourished patients undergoing major gastrointestinal surgery should receive 7 to 14 days of preoperative specialized nutrition support if the operation can be safely postponed (1). (Refer to Signs of Nutritional Deficiencies for guidelines to identify patients who are malnourished or may become malnourished.) Postoperative specialized nutrition support should be administered to patients who are not anticipated to resume adequate oral intake for 7 to 10 days (1). Patients who are hypermetabolic, critically ill, or malnourished may require specialized nutrition support therapy before 7 days to prevent catabolism (1).

Contraindications
Specialized nutrition support is usually not indicated for: malnourished patients who are eating adequate amounts to meet their estimated nutrient requirements; well-nourished patients who are anticipated to resume adequate oral intake within 7 days; and patients whose prognosis does not warrant aggressive nutritional care (1,5).

*The American Dietetic Association has assigned grades, ranging from Grade I (good/strong) to Grade V (insufficient evidence), to evidence and conclusion statements. The grading system is described in Clinical Nutrition Management A Reference Guide.

References

ASPEN Board of Directors and the Clinical Guidelines Task Force. Guidelines for the use of parenteral and enteral nutrition in adult and pediatric patients[published erratum appears in J Parenter Enteral Nutr. 2002;26:144]. J Parenter Enteral Nutr. 2002;26 (suppl 1):1SA-138SA.
ASPEN Board of Directors and Standards Committee. American Society for Parenteral and Enteral Nutrition. Definition of terms, style, and conventions used in A.S.P.E.N. guidelines and standards. Nutr Clin Pract. 2005;20:281-285.
Critical Illness Evidence-Based Nutrition Practice Guideline. American Dietetic Association Evidence Analysis Library. American Dietetic Association; 2006. Available at: http://www.adaevidencelibrary.com. Accessed October 15, 2007.
Braunschweig CL, Levy P, Sheean PM, Wang X. Enteral compared with parenteral nutrition: a meta-analysis. Am J Clin Nutr. 2001;74:534-542.
Maillet JO, Potter RL, Heller L. Position of the American Dietetic Association: ethical and legal issues in nutrition, hydration, and feeding. J Am Diet Assoc. 2002;102:716-726.