Parenteral Nutrition

Nutritional support refers to the provision of nutrients to individuals who are unable to maintain adequate nutritional status due to derangements in nutritional intake, malabsorption, or altered metabolism. The nutrition assessment process is a critical step in identifying patients who are at nutritional risk. It incorporates both subjective (medical and nutrition histories) as well as objective (physical examination, anthropometric measurements, laboratory tests, etc.) parameters to determine those in whom nutritional support would be beneficial. Nutritional support can be in the form of oral, enteral, or parenteral administration of nutrients. Enteral nutrition allows nourishment via a liquid diet formulation and is accomplished through a tube placed in the upper gastrointestinal tract (i.e., nasogastric, gastrostomy, nasointestinal, and jejunostomy). Parenteral nutrition, which is a compounded formulation of crystalline amino acids, dextrose, fats, electrolytes, vitamins, and minerals, is utilized in situations where the gastrointestinal tract is not functioning or cannot be accessed or in those cases where adequate nutrition cannot be attained by enteral or oral means alone. The advent of parenteral nutrition has revolutionized the management of very ill patients who are unable to maintain adequate nutritional intake. The purpose of this article is to review the indications and contraindications of parenteral nutrition for adult nutritional support, to describe the individual components utilized in formulating parenteral nutrition, to identify complications associated with parenteral nutrition, and to review important elements in the implementation and monitoring of parenteral nutrition, which are necessary to promote safe and effective utilization.