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Source: Kumpf VJ, Chessman KH. Enteral nutrition. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. Accessed March 23, 2017.


  • Delivery of nutrients by tube or mouth into gastrointestinal (GI) tract.

    • Focus of entry: delivery through feeding tube.


  • Usable fuels generated through digestion and absorption.

    • Digestion: stepwise conversion of complex chemical and physical nutrients via mechanical, enzymatic, and physicochemical processes into molecular forms that can be absorbed from GI tract.

    • Absorption occurs across intestinal cell membrane.

      • Nutrients reach systemic circulation through portal venous or splanchnic lymphatic systems.


  • Enteral nutrition (EN) indicated in patients who cannot or will not eat enough to meet nutritional requirements.

    • Requires both a functioning GI tract to allow for nutrient absorption, and a safe method of enteral access.

    • Typically indicated for patients with a variety of conditions or disease states such as stroke, cancer, altered mental status, etc.

  • Contraindicated with mechanical obstruction, bowel ischemia, uncorrectable coagulopathy, active peritonitis, and necrotizing enterocolitis.

  • EN success may be challenged with:

    • Severe diarrhea.

    • Protracted vomiting.

    • Enteric fistulas.

    • Severe GI hemorrhage.

    • Intestinal dysmotility.

  • Advantages of EN over parenteral nutrition (PN):

    • Maintaining GI tract structure and function.

    • Fewer metabolic, infectious, and technical complications.

    • Lower costs.

  • Initiate EN within 24–48 hours of hospitalization for critically ill patients.

  • Delay EN until oral intake inadequate for 5–7 days in mild to moderately stressed, well-nourished patients.


  • Provide calories, macronutrients, and micronutrients to patients unable to achieve these requirements from oral diet.


  • Enteral access.

    • Four routes of administration.

      • Indications, tube placement options, advantages, and disadvantages in Table 1.

      • Choice depends on anticipated duration of use and feeding site (stomach vs. small bowel).

  • Administration methods.

    • Continuous.

      • Preferred for initiation.

      • Well tolerated.

      • Increased costs due to pump and administration.

    • Cyclic.

      • Increased mobility due to breaks from infusion system.

    • Bolus.

      • Commonly used in long-term care residents with gastrostomy tube.

      • Minimal equipment and administration time required (5–10 min)

      • Potential side effects:

        • Cramping.

        • Nausea.

        • Vomiting.

        • Aspiration.

        • Diarrhea.

    • Intermittent.

      • Similar to bolus except that administration time longer (20–60 min)

      • Improved tolerability but more equipment.

  • Initiation.

    • Optimize achievement of nutrient goals by improved GI tolerance with use of initiation and advancement protocols.

    • Continuous EN feedings.

      • Adults: 20–50 mL/hour and advanced by 10–25 mL/hour every 4–8 hours until goal achieved.

      • Children: 1–2 mL/kg/h.

      • Premature infants: 10–20 mL/kg/day.

    • Intermittent EN feedings:

      • Adults: 120 mL every 4 hours and advanced by 30–60 mL every 8–12 hours.

    • Bolus.

      • Children: 2–4 mL/kg per bolus with advancement by similar amounts every 4–24 hours.

  • Formulations.

    • Provide essential nutrients, including macronutrients (eg, carbohydrates, fats, and proteins) and micronutrients (eg, electrolytes, trace elements, vitamins, and water).

    • Proteins: molecular form ...

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