Should patients on high doses of levophed (norepinephrine) be fed?

Feeding Patients on High-Dose Norepinephrine

Patients on high doses of norepinephrine (≥0.3 μg/kg/min) should not receive full enteral nutrition until they are hemodynamically stabilized and weaned from high-dose vasopressors.

Rationale for Delaying Full Feeding During Vasopressor Support

Enteral nutrition (EN) during high-dose vasopressor therapy presents significant risks due to:

1. Compromised Splanchnic Circulation: High-dose vasopressors cause significant vasoconstriction in the splanchnic circulation, potentially leading to:

   • Intestinal ischemia
   • Impaired nutrient absorption
   • Increased risk of feeding intolerance

2. Evidence-Based Concerns: Recent guidelines specifically caution against early high-dose feeding in patients on high-dose vasopressors:

   • The Personalized Nutrition in Critical Care guidelines (2023) recommend avoiding higher doses of protein in "well-nourished mechanically ventilated patients admitted to ICU in shock on high doses of vasopressors (doses of norepi. ≥0.2 μg/kg/min)" 1
   • The Nutrirea-3 trial showed increased ICU length of stay by one day in patients on high-dose vasopressors (admission norepinephrine: 0.5 μg/kg/min) who received full nutrition compared to those on low-dose nutrition 1

Recommended Feeding Approach for Patients on High-Dose Norepinephrine

Phase 1: During High-Dose Vasopressor Support (≥0.3 μg/kg/min)

• Provide hypocaloric nutrition (not exceeding 70% of energy expenditure)
• Limit protein to ≤0.8 g/kg/day until patient is stabilized and weaning off vasopressors 1
• Consider low-dose enteral nutrition (10-15 kcal/kg/day) if the patient has an intact and functioning GI tract

Phase 2: During Vasopressor Weaning (Norepinephrine <0.3 μg/kg/min)

• Gradually increase nutrition as vasopressor requirements decrease
• Monitor for feeding intolerance (high gastric residuals, abdominal distension)
• Consider prokinetic agents (metoclopramide) if feeding intolerance occurs 1

Phase 3: After Vasopressor Discontinuation

• Progress to full nutritional support (25-30 kcal/kg/day) 1
• Increase protein to >1.2 g/kg/day 1

Monitoring Parameters During Feeding

1. Signs of Feeding Intolerance:

   • Increased gastric residual volumes (>500 ml/6h) 1
   • Abdominal distension
   • Worsening hemodynamic parameters after feeding initiation

2. Metabolic Parameters:

   • Lactate levels (rising levels may indicate intestinal ischemia)
   • Blood glucose (maintain appropriate glycemic control)

Special Considerations

• Alternative Feeding Routes: Post-pyloric feeding may be considered in patients with high gastric residuals but should still follow the hypocaloric approach during high-dose vasopressor therapy
• Parenteral Nutrition: Consider supplemental parenteral nutrition only if enteral route is contraindicated and after patient is hemodynamically stabilized 1

Common Pitfalls to Avoid

1. Aggressive Early Feeding: The ESPEN guidelines caution that "early high-dose feeding should be avoided until patient is stabilized early in ICU stay" 1

2. Ignoring Signs of Intestinal Ischemia: Abdominal distension, increasing lactate, or worsening hemodynamics after feeding initiation should prompt immediate feeding cessation

3. One-Size-Fits-All Approach: While general guidelines recommend caution with feeding during high-dose vasopressor therapy, individual assessment of hemodynamic stability and resuscitation status remains important

The evidence clearly supports a cautious approach to feeding patients on high-dose norepinephrine, with gradual advancement of nutrition as hemodynamic stability improves and vasopressor requirements decrease.