Chapter 073. Enteral and Parenteral Nutrition (Part 1)

Harrisons Internal Medicine Part 4. Nutrition Chapter 73. Enteral and Parenteral Nutrition TherapyEnteral and Parenteral Nutrition Therapy: IntroductionThe ability to provide specialized nutritional support (SNS) represents a major advance in medical therapy. Nutritional support, via either enteral or parenteral routes, is used in two main settings: (1) to provide adequate nutritional intake during the recuperative phase of illness or injury, when the patients ability to ingest or absorb nutrients is impaired, and (2) to support the patient during the systemic response to inflammation, injury, or infection during an extended critical illness.SNS is also used in patients with...
Nội dung trích xuất từ tài liệu:
Chapter 073. Enteral and Parenteral Nutrition (Part 1) Chapter 073. Enteral and Parenteral Nutrition (Part 1) Harrisons Internal Medicine > Part 4. Nutrition > Chapter 73. Enteraland Parenteral Nutrition Therapy Enteral and Parenteral Nutrition Therapy: Introduction The ability to provide specialized nutritional support (SNS) represents amajor advance in medical therapy. Nutritional support, via either enteral orparenteral routes, is used in two main settings: (1) to provide adequate nutritionalintake during the recuperative phase of illness or injury, when the patients abilityto ingest or absorb nutrients is impaired, and (2) to support the patient during thesystemic response to inflammation, injury, or infection during an extended criticalillness. SNS is also used in patients with permanent loss of intestinal length orfunction. In addition, an increasing number of elderly patients living in nursinghomes and chronic care facilities receive enteral feeding, usually as a consequenceof inadequate nutritional intake. Enteral refers to feeding via a tube placed into the gut to deliver liquidformulas containing all essential nutrients. Parenteral refers to the infusion ofcomplete nutrient solutions into the bloodstream via a peripheral vein or, morecommonly, by central venous access to meet nutritional needs. Enteral feeding is generally the preferred route because of benefits derivedfrom maintaining the digestive, absorptive, and immunologic barrier functions ofthe gastrointestinal tract. Small-bore pliable tubes have largely replaced large-borerubber tubes, making placement easier and more acceptable to patients. Infusionpumps have also improved the delivery of nutrient solutions. For short-term use, enteral tubes can be placed via the nose into thestomach, duodenum, or jejunum. For long-term use, these sites can be accessedthrough the abdominal wall using endoscopic, radiologic, or surgical procedures.Intestinal tolerance of tube feeding may be limited during acute illness by gastricretention or diarrhea. Parenteral feeding has greater risk of infection, reflecting theneed for venous access, and a greater propensity for inducing hyperglycemia.However, these risks can generally be managed successfully by SNS teams. Forthe postoperative patient with preexisting malnutrition, or in trauma patients whowere previously well nourished, SNS is strikingly cost-effective. In the mostcritically ill patient in the intensive care unit, SNS can dramatically enhancesurvival. Although enteral nutrition (EN) can be provided by most health careteams caring for hospitalized patients, safe and effective parenteral nutrition (PN)usually requires specialized teams. Approach to the Patient: Requirements for Specialized NutritionalSupport Indications for Specialized Nutritional Support Although at least 15–20% of patients in acute care hospitals have evidenceof significant malnutrition, only a small fraction will benefit from SNS. For others,wasting is an inevitable component of a terminal disease and the course of thedisease will not be altered by SNS. The decision to use SNS should be based on the likelihood that preventingprotein-calorie malnutrition (PCM) will increase the likelihood of recovery, reduceinfection rates, improve healing, or otherwise shorten the hospital stay. In the case of the elderly or chronically ill patient for whom full recovery isnot anticipated, the decision to feed is usually based on whether SNS will extendthe duration and quality of life. The decision-making process used to decide whento use SNS is depicted in Fig. 73-1. Figure 73-1