Is it safe to feed patients on vasopressors (vasoactive medications)?

Feeding Patients on Vasopressors: Safety and Recommendations

Yes, it is safe to feed patients on low-to-moderate dose vasopressors who are adequately resuscitated, but you must avoid high-dose feeding in patients on high-dose vasopressors (norepinephrine ≥0.3 mcg/kg/min) until they are stabilized and weaning. 1

Key Decision Algorithm: When to Start and What Dose

Safe to Initiate Enteral Nutrition (EN):

• Norepinephrine <0.3 mcg/kg/min with normalized lactate (adequately resuscitated) 1
• Stable or decreasing vasopressor doses 1
• No escalating vasopressor requirements 1

Contraindications - Do NOT Feed:

• Norepinephrine ≥0.3 mcg/kg/min (high-dose vasopressors) 1
• Unresuscitated hemodynamic instability with persistent lactic acidosis 1
• Escalating vasopressor support 1
• Abdominal distension, gastrointestinal bleeding, or new abdominal pain 1

Feeding Strategy Based on Vasopressor Dose

Low-Dose Vasopressors (Norepinephrine <0.3 mcg/kg/min):

• Start trophic/hypocaloric EN at 10-15 kcal/kg/day or <70% of measured energy expenditure 1
• Protein: ≤0.8 g/kg/day initially, then progressively increase to >1.2 g/kg/day as patient stabilizes 1
• This approach is supported by the 2023 Critical Care guidelines emphasizing personalized nutrition 1

High-Dose Vasopressors (Norepinephrine ≥0.3 mcg/kg/min):

• Avoid high-dose feeding until vasopressor weaning occurs 1
• If feeding is attempted, use very low doses: 6 kcal/kg/day with 0.2-0.4 g/kg/day protein 1
• The NUTRIREA-3 trial demonstrated increased ICU length of stay with full nutrition (25 kcal/kg/day) versus low-dose nutrition in patients on vasopressors 1

Evidence Supporting Safety

Observational data strongly supports early EN in stabilized patients on vasopressors:

• A large observational study showed early EN (<48 hours) in patients with stable hemodynamics on vasopressors was associated with **reduced mortality** compared to late EN (>48 hours) 1
• A multi-institutional study of 1,174 mechanically ventilated patients on vasopressors found early EN was associated with lower ICU mortality (22.5% vs 28.3%) and hospital mortality (34.0% vs 44.0%) 2
• The benefit was most evident in the sickest patients requiring multiple vasopressors 2

However, the risk of bowel ischemia exists:

• Non-occlusive mesenteric ischemia (NOMI) occurs in <1% of patients, but is life-threatening 1
• The 2022 World Society of Emergency Surgery guidelines note that vasopressors like norepinephrine and epinephrine can impair mucosal perfusion 1
• The NUTRIREA-2 trial found significantly higher rates of bowel ischemia with enteral versus parenteral nutrition in critically ill patients 1

Critical Monitoring Parameters

You must monitor for signs of bowel ischemia:

• Unexplained abdominal distension 1
• Gastrointestinal bleeding or passage of maroon/bright red blood 1
• New onset organ failure or increased vasoactive support 1
• Nutrition intolerance (elevated gastric residual volumes, vomiting) 3
• Worsening metabolic acidosis 1

A retrospective study found 20% of patients on vasopressors had elevated gastric residual volumes versus 7% without vasopressors, but no difference in bowel ischemia rates 3

Vasopressor-Specific Considerations

Not all vasopressors affect splanchnic perfusion equally:

• Norepinephrine and epinephrine may impair mucosal perfusion 1
• Dobutamine, low-dose dopamine, and milrinone have less impact on mesenteric blood flow 1
• Vasopressin and digoxin can worsen ischemia 1

Common Pitfalls to Avoid

Do not delay EN indefinitely in patients on stable low-dose vasopressors - this is associated with worse outcomes 1, 2

Do not push full-dose nutrition early in patients on high-dose vasopressors - wait until they are stabilizing and weaning 1

Do not ignore clinical signs in sedated ICU patients - approximately 25% of NOMI cases are undetectable in sedated patients, so maintain high suspicion with any negative physiologic changes 1

Do not assume all patients tolerate EN equally - patients with cardiopulmonary resuscitation, bacteremia, and diarrhea should raise suspicion for NOMI regardless of abdominal pain presence 1

Do not use vasopressor dose as the sole criterion - adequate resuscitation status (normalized lactate) is equally important 1