Enteral Nutrition (Tube Feeds)

Enteral Nutrition (Tube Feeds)

David Ray Velez, MD

Table of Contents

Feeding
Management
Formula Variations

Feeding

Initiation

  • Early Initiation (Within 48 Hours) is Generally Preferred
  • Preferred Over Total Parenteral Nutrition (TPN) if Able
  • Consider PEG Tube Placement if Not Eating for > 4 Weeks

Contraindications

  • Hemodynamic Instability on Vasopressor Support (Risk for Intestinal Ischemia is Debated)
    • Consider Trophic Tube Feeds (10-30 cc/hr) to Prevent Mucosal Atrophy
  • Bowel Ischemia
  • Major Upper GI Bleeding
  • Bowel Obstruction
  • Prolonged Ileus
  • Bowel Discontinuity (Open Abdomen Alone is Not a Contraindication)
  • Intractable Vomiting
  • *Fresh Anastomosis is Not a Contraindication & Early Enteral Nutrition Actually Improves Outcomes

Benefits

  • Early Enteral Feeding Increases Survival in Sepsis and Pancreatitis
  • IBD Patients Have Decreased Risk of Infectious Complications
  • Comparison to TPN:
    • Avoids Bacterial Translocation (Bacteria Within Gut Lumen Traverse Intestinal Wall and Colonize Mesenteric Lymph Nodes)
    • Avoids TPN Complications

Access Site

  • Gastric
    • Generally Preferred
    • Easier to Place and Better Approximation of Normal Physiology
    • Contraindications:
      • Nasogastric Tube Output > 600 cc/Day
      • History of Aspiration
      • Lack of Adequate Airway Protection
      • Severe Pulmonary Dysfunction
      • Recent Regurgitation
      • Unable to Maintain 30-Degree Reverse Trendelenburg Position
  • Postpyloric/Jejunal
    • Preferred if at Risk for Aspiration (Delayed Gastric Emptying or Severe GERD)
    • Decreased Risk of Aspiration Pneumonia (30% Reduction)
    • No Difference in Mortality or Other Clinical Outcomes

Feeding Schedule

  • Bolus
    • Large Amounts Given Over Short Periods (≤ 5 Minutes)
    • Use Only for Gastric Feeding, Not Postpyloric (Will Not Tolerate Such a Large Volume)
    • Most Likely to Cause GI Side Effects
  • Intermittent
    • Can Use for Either Gastric or Postpyloric Feedings
  • Continuous
    • Can Use for Either Gastric or Postpyloric Feedings
    • Usually the Best Tolerated Method, Especially in the Postoperative Period or ICU Setting

Management

Nasal Tube Bridling

  • Definition: A System to Secure the Feeding Tube Around the Nasal Septum
  • Decreases Risk of Tube Dislodgement, Resulting in Improved Caloric Intake

Enteral Feeding Intolerance (EFI)

  • Definition: Vomiting or Large Volume Residuals Due to Gastroparesis/Delayed Gastric Emptying
  • Treatment: Prokinetic Agents
    • Metoclopramide (Reglan) or Erythromycin
    • Some Data Suggests Erythromycin May Be More Effective but Increases QT Prolongation

Gastric Residual Volumes (GRV)

  • Definition: Placing a Feeding Tube to Suction at Defined Intervals to Monitor Residual Volumes with the Belief that High Residual Volumes Indicate Enteral Feeding Intolerance
    • Typically Checked Every 4-8 Hours Once Tube Feeds are Initiated
    • Consider Holding Enteral Feeds if Volumes are Large ≥ 400-500 cc
    • Consider Starting Reglan or Erythromycin with High Residuals
  • Checking Residuals Does Not Prevent Aspiration and Has Shown No Benefit – Further Contributes to Malnutrition and Guidelines Recommend Against Their Use

Clamp Trial

  • Generally Performed when Considering Removal of a Nasogastric Tube
    • Used if Tube Has Been Set to Suction (Not Necessary if Being Used for Feeding)
  • Clamp Tube (Take Off Suction) for 4 Hours and Then Check the Residual Volume
  • Tube Removed if Residuals < 125 cc (Exact Amount is Poorly Defined)
  • Benefit is Questioned and Many Recommend Removal When Clinically Ready without a Clamp Trial

Formula Variations

Formula Variations

  • Elemental (Predigested) Formula
    • Protein and Carbs are Already Partially Digested
    • Possible Indications:
      • Malabsorptive Syndromes
      • Chylothorax or Chylous Ascites
      • Failure to Tolerate Standard Formula (Persistent Diarrhea)
    • *No Proven Benefit Over Standard Formula
  • Concentrated Formula
    • Higher Nutritional Concentration with Low Fluid Volume
    • Used for Critically Ill Patients Requiring Volume Restriction
  • Hepatic Formula
    • High Levels of Branched Chain Amino Acids (Leucine, Valine, Isoleucine) and Low Levels of Aromatic Amino Acids (Phenylalanine, Tyrosine, Tryptophan)
    • Branched Chain Amino Acids Stimulate Ammonia Detoxification
    • Largely Considered for Hepatic Encephalopathy
    • *No Proven Benefit Over Standard Formulas – Particularly if Already Receiving First-Line Therapies (Lactulose and Antibiotics)
    • *Historically Used Low-Protein Formulas but Data Shows Worse Nutrition and Muscle Loss
  • Renal Formula
    • Low Protein and Nitrogen with High Calories (Reduced Volume)
    • *Generally Not Used in AKI – Critically Ill Patients Have High Protein Losses

Immunonutrition Supplementation

  • Glutamine
    • Involved in Immune Functions
    • Used by Enterocytes and May Reduce Intestinal Mucosal Permeability/Bacterial Translocation
    • Particularly Recommended for TBI and Perioperative SICU Patients
  • Arginine
    • Decreases Risk of Postoperative Infection and Promotes Wound Healing but May Increase Mortality in Sepsis
    • Contraindicated in Sepsis and Septic Shock
  • Omega-3 Fatty Acids
    • Reduce Proinflammatory Molecule Production
  • Antioxidants (Vitamins C/D/E, Selenium, Zinc, Copper)
    • Inhibit Oxygen Free Radicals
    • Recommend Against the Use of Vitamin C in Sepsis
    • IV Vitamin C Can Interfere with POC Glucose (Risk for Life-Threatening Hypoglycemia)
    • Selenium is Believed to Be One of the Most Effective in the Clinical Setting
  • *No Clear Benefit in the Literature to Immunonutrition and Their Role is Poorly Established