- The GI tract defends the host from toxins and antigens by both immunologic and nonimmunologic mechanisms, collectively referred to as the gut barrier function. Whenever possible, enteral nutrition (EN) is preferred over parenteral nutrition (PN) because it is as effective, may reduce metabolic and infectious complications, and is less expensive.
- Candidates for EN are those with a sufficiently functioning GI tract to allow adequate nutrient absorption who cannot or will not eat and in whom enteral access can be safely obtained.
- The most common route for both short- and long-term EN access is directly into the stomach. The method of delivery may be either continuously via an infusion pump, intermittently via a pump or gravity drip, or by gravity or syringe bolus administration.
- Patients unable to tolerate feeding directly into the stomach because of impaired gastric motility and for those at high risk of aspiration, feeding tube tip placement into the duodenum or jejunum may be indicated. When feeding into the small bowel, the continuous method of delivery via an infusion pump is required to enhance tolerance.
- Selection of the enteral feeding formulation depends on nutritional requirements, the patient’s primary disease state and related complications, and nutrient digestibility and absorption. A standard polymeric formulation will meet the needs of the majority of adults and children.
- Measurement of gastric residual volumes can be used to monitor GI tolerance in patients receiving gastric feeding. Although not always reliable, excessive residual volumes may be associated with nausea, abdominal distension, and increased aspiration risk.
- Management of diarrhea in patients receiving EN should focus on identification and correction of the most likely cause(s). Tube feeding-related causes include too rapid delivery or advancement, intolerance to the formula composition, and occasionally formula contamination.
- Prior to administering medications through a feeding tube, the feeding tube tip location should be verified (stomach or small bowel) and the most suitable dosage form selected. Medications that should not be crushed and administered through a tube include enteric-coated or sustained-release capsules or tablets and sublingual or buccal tablets.
- The coadministration of medications with EN can result in alterations in bioavailability and/or changes in the desired pharmacologic effects. Medications known to interact with EN include phenytoin, warfarin, selected antibiotics, antacids, and proton-pump inhibitors.
On completion of this chapter, the reader will be able to:
Discuss the basic mechanisms of carbohydrate, fat, and protein digestion and absorption.
Describe how the GI tract defends the host from toxins and antigens and the impact of feeding on gut barrier function.
Identify appropriate indications for the use of enteral nutrition (EN).
List potential advantages to the use of EN compared to parenteral nutrition.
Identify enteral access options, including the gastric and small bowel route for both short-term and long-term use.
Select the appropriate administration method of EN (e.g., continuous, cyclic, bolus, and intermittent).
Differentiate between the various classes of enteral feeding formulations.
Select an appropriate enteral formula to meet the needs of a given adult and pediatric ...