What are the guidelines for initiating and managing enteral nutrition (EN) in patients?

Enteral Nutrition: Guidelines for Initiation and Management

When to Initiate Enteral Nutrition

Enteral nutrition should be initiated in all patients who are not expected to resume a full oral diet within 3 days. 1, 2

• In ICU patients who are hemodynamically stable with a functioning gastrointestinal tract, begin enteral nutrition within the first 24 hours of admission. 1, 2
• Early enteral nutrition (within 48 hours) significantly reduces infectious complications (RR 0.50) and shortens both ICU stays and hospital stays compared to total parenteral nutrition. 2
• For cancer patients, start nutritional therapy if undernutrition already exists or if inadequate food intake (<60% of estimated energy expenditure for >10 days) is anticipated. 1

Energy Delivery Targets

During the acute phase of critical illness, limit energy provision to 20-25 kcal/kg body weight/day to avoid overfeeding, which is associated with worse outcomes. 1, 2

• Exceeding 25 kcal/kg/day during the acute phase may worsen outcomes and increase metabolic complications. 1, 2
• During the anabolic recovery phase, increase energy provision to 25-30 kcal/kg body weight/day. 1, 2
• In severely undernourished patients, target 25-30 total kcal/kg body weight/day from the start. 1

Protein Requirements

Provide low-dose protein (maximum 0.8 g/kg/day) during the early phase of critical illness, then increase to >1.2 g/kg/day during the rehabilitation phase. 3

• For cancer patients and those under moderate stress, target 1.0-1.5 g/kg/day depending on stress level. 4
• Avoid excessive protein restriction (<0.8 g/kg/day) unless specific renal indications exist, as this worsens nutritional status. 4

Route of Administration

Use the enteral route whenever the gastrointestinal tract is functioning; enteral nutrition is superior to parenteral nutrition. 1, 2

• There is no significant difference in efficacy between jejunal and gastric feeding in most critically ill patients. 1, 2
• Begin with nasogastric tube feeding; if gastric intolerance occurs (high gastric residuals, vomiting), advance to post-pyloric (nasojejunal) feeding. 4, 5
• Use percutaneous access (gastrostomy or jejunostomy) when enteral nutrition is anticipated for ≥4 weeks. 3
• For patients with gastroparesis unresponsive to prokinetic treatment, nasojejunal tube feeding is the preferred route. 4

Formula Selection

Standard whole protein polymeric formulas are appropriate for most patients, as no clinical advantage of peptide-based formulas has been demonstrated. 1, 2

• For diabetic patients, use modified enteral formulas with lower sugar content, slowly digestible carbohydrates, and enriched monounsaturated fatty acids. 4
• Most formulations should be lactose-free, as lactose intolerance may occur during critical illness. 5
• Use age-adapted standard polymeric formula enriched with fibers for most pediatric patients. 6

Special Populations and Immune-Modulating Formulas

Immune-modulating formulas (enriched with arginine, nucleotides, and omega-3 fatty acids) should NOT be used routinely in severe sepsis or patients with APACHE II score >15, as they may be harmful. 1

• Immune-modulating formulas are superior to standard formulas in elective upper GI surgical patients and patients with mild sepsis (APACHE II <15). 1
• For patients with ARDS, use formulas containing omega-3 fatty acids and antioxidants. 1
• Glutamine should be supplemented in patients suffering from burns or trauma. 1

Managing Feeding Intolerance

For patients with gastric intolerance (high gastric residuals), administer intravenous metoclopramide or erythromycin before abandoning enteral nutrition. 1

• Start enteral nutrition at low rates and increase slowly over days until requirements are met. 2
• Vomiting and increased gastric residual volume indicate gastric intolerance, while sudden abdominal pain, distension, or rising abdominal pressure indicate lower gastrointestinal intolerance. 3
• A plasma phosphate drop of 30% should prompt reduction of feeding rate and high-dose thiamine to prevent refeeding syndrome. 3

When to Add Parenteral Nutrition

Avoid supplementary parenteral nutrition in patients who tolerate enteral nutrition and can be fed approximately to target values. 1

• Use supplemental parenteral nutrition only in patients who cannot be fed sufficiently via the enteral route after 3-7 days, especially in severely malnourished patients. 1, 2
• When adding parenteral nutrition, use caution to avoid overfeeding, which contributes to infectious complications. 2

Critical Pitfalls to Avoid

• Delayed initiation: All ICU patients who won't resume full oral diet within 3 days should receive nutritional support; delays can be harmful. 2
• Overfeeding during acute phase: Providing >25 kcal/kg/day during the acute phase worsens outcomes. 2
• Premature abandonment of enteral nutrition: High gastric residuals should prompt prokinetic intervention rather than switching to parenteral nutrition. 2
• Ignoring refeeding syndrome: Monitor electrolytes and phosphorus levels daily, especially when initiating nutrition in malnourished patients. 2, 3
• Using immune-modulating formulas in severe sepsis: These formulas may be harmful in patients with APACHE II >15. 1