Chapter 18: Enteral and Parenteral Nutrition

INTRODUCTION

DEFINITIONS

Nutritional support is the provision of nutrients with therapeutic intent by either the enteral or the parenteral route. Technically, the term enteral nutrition includes oral supplements as well as tube feeding, but in practice, clinicians usually use the term to refer strictly to tube feeding. Parenteral nutrition (PN) refers to the intravenous administration of nutrition that may include protein, carbohydrate, fat, minerals and electrolytes, vitamins, and other trace elements. Parenteral nutrition is sometimes referred to as total parenteral nutrition (TPN). PN is reserved for patients who are unable to eat or absorb enough food through tube feeding or by mouth to maintain a good nutrition status.

Enteral and parenteral nutrition are important in the management of many medical conditions. Safe and effective nutritional therapy depends on careful selection for the individualized patient and a thorough understanding of the complications that can occur. Principles of nutritional assessment and oral diets are presented in Chapter 17, Nutritional Assessment, Therapeutic Diets, and Infant Feeding.

ENTERAL NUTRITION

“If the gut works, use it.” This simple adage is the guiding principle of nutritional support. Clinical practice guidelines consistently endorse the use of enteral nutrition for patients who have a functional GI tract but cannot take enough nutrients orally to maintain adequate nutritional goals. Enteral nutrition has physiologic and practical benefits that make tube feeding superior to parenteral nutrition (Table 18-1).

Technological advances in enteral access techniques have increased the numbers of patients who can safely receive tube feeding. The indications for enteral nutrition are summarized in Table 18-2.

Principles of Enteral Tube Feeding

Timing: The optimal time for initiating enteral nutrition depends on the patient’s baseline nutritional status and ...