Enteral Nutrition

Aka: Enteral Nutrition, Nutritional Supplement, Dietary Supplementation

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II. Defintions

  1. Nutritional Support Therapy
    1. Formulated enteral or Parenteral nutrients given to Restore nutritional status
  2. Enteral Nutrition
    1. Gastrointestinal Tract delivery of Nutritional Support
  3. Parenteral Nutrition
    1. Intravenous delivery of Nutritional Support

III. Indications

  1. See Malnutrition
  2. See Nutrition in the Intensive Care Unit

IV. Contraindications

  1. Severe gastrointestinal dysfunction (refractory Vomiting, ileus or Bowel Obstruction)
  2. Hemodynamic instability
  3. Multisystem organ failure

V. Evaluation

  1. See Nutrition Support
  2. See Subjective Global Assessment of Nutritional Status
  3. See Lab Markers of Malnutrition

VI. Technique: Enteral Nutrition devices

  1. Nasogastric Tube
    1. Indicated in short-term enteral support (e.g. hospitalized patients)
  2. Enterostomy Tube
    1. Indicated in long-term enteral support
    2. Gastrostomy Tube
      1. Gastric feeding is typically preferred for more physiologic intake and larger volumes
    3. Jejunostomy Tube (Post-pyloric feeding) Indications
      1. Aspiration risk
      2. Severe Esophagitis
      3. Gastric dysmotility or gastric obstruction
      4. Recurrent Emesis
      5. Pancreatitis

VII. Technique: Feeding Protocols

  1. Bolus Feedings
    1. Most closely resembles physiologic intake
    2. Indicated in non-critically ill patients with intact Gag Reflex and normal gastrointestinal function
  2. Intermittent Feedings
    1. Delivered over 20-30 minutes in non-critically ill patients unable to tolerate bolus feedings
  3. Cyclic Feedings
    1. Delivered over 8 to 16 hours via feeding pump
  4. Continuous Feedings
    1. Delivered over 12-24 hours via feeding pump

VIII. Preparations: Polymeric Formulations (Intact or whole macronutrient formulas)

  1. Polymeric - Standard
    1. Isotonic, lactose-free, nutritionally complete formulas
    2. Indicated for normal Gastrointestinal Tract
    3. Adult: 1-1.2 kcal/ml
      1. Boost, Ensure, Isocal, Jevity 1.2, Nutren 1.0, Osmolite
    4. Child: 1 kcal/ml or 30 kcal/oz
      1. Boost kid essentials, Pediasure, Nutren Junior
  2. Polymeric - High Calorie
    1. Concentrated formulas with significantly higher calories per ml (typically by increasing fat concentration)
    2. Indicated for fluid restriction (CHF, SIADH) or high calorie requirement (e.g. Trauma)
    3. Adult: 2 kcal/ml
      1. Deliver 2.0, Novasource 2.0, Nutren 2.0, Twocal HN
    4. Child: 1.5 kcal/ml or 45 kcal/oz
      1. Boost kid essentials 1.5, Resource Just for Kids 1.5
  3. Polymeric - High Protein
    1. Indicated for hypercatabolic state or high Protein requirement (e.g. Wound Healing)
    2. Adult: 1-1.5 kcal/ml with Protein comprising 18-25% of total calories
      1. Boost high Protein, Ensure plus HN, Isocal HN, Isosource HN, Osolite 1.2 CAL, Replete, Sustacal HC
  4. Polymeric - With fiber
    1. Isotonic, typically soy-based fiber of both soluble and insoluble types with 4-22 grams fiber per Liter
    2. Indicated for prevention of Diarrhea in the short-term, and Constipation in the long-term
    3. Adult: Ensure with fiber, Fibersource HN, Jevity, Ultracal
    4. Child: Nutren Junior with fiber, Pediasure with fiber
  5. Blenderized
    1. Pureed natural foods
    2. Indicated for longterm enteral support and intact gastrointestinal function

IX. Preparations: Elemental Formulations

  1. Oligomeric
    1. Elemental formula, Proteins with short peptides and free Amino Acids, higher osmolarity and lactose-free
    2. Provide 1-1.5 kcals/ml
    3. Indicated for malabsorption syndromes and pancreatic insufficiency
    4. Disadvantages: Expensive, may worsen Diarrhea
    5. Adults: Criticare HN, Peptamen, Perative, Subdue, Tolarex, Vital HN, Vivonex TEN, Vivonex Plus
    6. Child: Peptamen Junior, Vivonex Pediatric
  2. Modular Formulation
    1. Indicated for a specific nutrient deficiency or as a component in a multi-formulation plan
    2. Protein formulations: Beneprotein instant Protein powder, Promod
    3. Carbohydrate formulations: Moducal, Polycose
    4. Fat formulations: MCT Oil, Microlipid
    5. Fiber formulations: Benefiber

X. Preparations: Disease Specific Formulations

  1. Diabetic Formulation
    1. Lower Carbohydrate, higher monounsaturated fat, and higher fiber; 1 kcal/ml
    2. Preparations: Choice DM, Diabetisource, Glucerna, Glytrol
  2. Immunomodulating Formulation
    1. Higher Protein, with increased Arginine, Glutamine, Omega-3 Fatty Acids and other components
    2. Provides components thought to improve immune response
    3. Indicated in ICU patients with major Trauma, burns, or the critically ill on Mechanical Ventilation
    4. Deliver 1-1.5 kcal/ml
    5. Preparations: Alitraq, Crucial, Impact
  3. Pulmonary Formulation
    1. Low Carbohydrate, high fat, no fiber formulations with 1.5 kcal/ml
      1. Some contain Omega-3 Fatty Acids and antioxidants which may be considered in Acute Lung Injury or ARDS
    2. Indicated for COPD, Mechanical Ventilation weaning (formulated to reduce carbon dioxide production)
    3. Preparations: Nutren, Nutrivent, Oxepa, Pulmocare
  4. Renal Formulation
    1. Formulations with reduced Potassium, Phosphorus and Magnesium; available in low and high Protein formulations
    2. High Protein formulation (for renal replacement therapy): Magnacal Renal, Nepro
    3. Low Protein formulation (if not ion Dialysis): Novasource Renal, Renalcal, Suplena

XI. Labs

  1. Baseline
    1. Complete Blood Count
    2. Glucose
    3. Electrolytes including Magnesium, phosphate, Calcium
    4. Renal Function tests
    5. Liver Function Tests including albumin
    6. Serum Iron
    7. Vitamin B12
    8. Vitamin D
    9. Zinc
    10. Copper
    11. Serum Folate
    12. INR
  2. Monitoring: Frequency based on clinical status
    1. Complete Blood Count
    2. Glucose (several times daily)
    3. Electrolytes including Magnesium, phosphate, Calcium
    4. Renal Function tests
    5. Liver Function Tests including albumin
      1. Expect 2-3 fold over baseline with 10-14 days TPN
  3. Monitoring: periodic recheck when on longterm Enteral Nutrition
    1. Vitamin B12
    2. Vitamin D
    3. Zinc
    4. Copper
    5. Serum Folate
  4. Other monitoring
    1. Gastric residuals every 4 to 6 hours when gastric feeding
    2. Monitor intake and output

XII. Complications

  1. See Refeeding Syndrome
  2. Aspiration Pneumonia (up to 44% of cases)
    1. Elevate head of bed to 30 degrees
    2. Measure gastric residuals periodically and adjust instillation volumes as needed
    3. Inflate endotracheal cuff if intubated
    4. Consider postpyloric feeding (Nasoduodenal tube or Jejunostomy)
  3. Diarrhea (up to 65% of cases)
    1. Management
      1. Evaluate for and treat underlying cause first
      2. Reduce rate and titrate more slowly
      3. Add fiber to formulation
      4. Consider antidiarrheal medication
    2. Causes
      1. Sorbitol containing elixirs
      2. Antibiotics with secondary Clostridium difficile
      3. Low fiber content
      4. High fat content
      5. Bacterial contamination of delivery device
      6. Hyperosmolar formulation
      7. Delivery rate too high
  4. Feeding Tube related complications
    1. See Feeding Tube
  5. Fluid, Electrolyte, and metabolic abnormalities
    1. Hyperglycemia
    2. Vitamin K Deficiency
    3. Trace element deficiency (zinc, copper)
    4. Vitamin B12 Deficiency
    5. Iron Deficiency
    6. Hypertonic Dehydration (calorie dense formulations with inadequate fluid intake)

XIII. References

  1. Bankhead (2009) JPEN J Parenter Enteral Nutr 33(2): 122-67 [PubMed]
  2. Bristrian (2006) Crit Care Med 34(5): 1525-31 [PubMed]
  3. Chen (2009) Nutr Clin Pract 24(3): 344-55 [PubMed]
  4. Koretz (2009) Nutr Clin Pract 24(3): 316-324 [PubMed]
  5. Kulick (2011) Am Fam Physician 83(2): 173-83 [PubMed]
  6. Lesser (2021) Am Fam Physician 104(6): 580-8 [PubMed]

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