Why can't tube feeding be done in a patient on high doses of vasopressors (pressors)?

From the Guidelines

Tube feeding should be avoided in patients on high doses of vasopressors (norepinephrine ≥ 0.3 ug/kg/min) due to the risk of non-occlusive mesenteric ischemia and other complications, and instead, consider parenteral nutrition or delayed enteral feeding until the patient is stabilized and pressor requirements decrease. The use of high-dose vasopressors indicates severe hemodynamic compromise, which can lead to reduced blood flow to the gastrointestinal tract, increasing the risk of gut ischemia and other serious complications 1.

Key Considerations

• The risk of non-occlusive mesenteric ischemia is dose-dependent, with higher pressor requirements indicating greater risk of gut ischemia 1.
• Instead of tube feeding, consider parenteral nutrition if the patient requires prolonged nutritional support.
• Once the patient is stabilized and pressor requirements decrease (typically when norepinephrine is less than 0.1-0.14 mcg/kg/min or equivalent doses of other pressors), you can cautiously initiate enteral feeding, starting with trophic rates (10-20 mL/hr) and monitoring for signs of feeding intolerance such as abdominal distension, increased gastric residuals, or worsening lactic acidosis.
• The Nutrirea-3 trial showed increased ICU LOS by one day in intubated patients on vasopressors (admit norepinephrine: 0.5 ug/kg/m) in low-dose nutrition group (6 kcal/kg/day//0·2–0·4 g/kg/day protein) vs full-nutrition (25 kcal/kg/day//1·0–1·3 g/kg/day protein), highlighting the importance of avoiding early high-dose feeding in patients on high doses of vasopressors 1.

Monitoring and Adjustments

• Monitor patients closely for signs of feeding intolerance and adjust the feeding plan as needed.
• Use indirect calorimetry to determine energy expenditure and guide nutrition therapy 1.
• Consider the use of specialized nutrients, such as HMB, creatine, and leucine, to improve strength, muscle mass, and lean mass, although more data is needed in ICU populations 1.

From the FDA Drug Label

DOSAGE & ADMINISTRATION Norepinephrine Bitartrate Injection is a concentrated, potent drug which must be diluted in dextrose containing solutions prior to infusion. Restoration of Blood Pressure in Acute Hypotensive States Blood volume depletion should always be corrected as fully as possible before any vasopressor is administered.

The patient on high doses of pressors, such as norepinephrine, may have vasoconstriction which can lead to decreased blood flow and tissue perfusion. Tube feeding may not be tolerated due to decreased gastrointestinal perfusion.

• Decreased perfusion of the gut can lead to malabsorption and increased risk of ischemia.
• High doses of pressors can cause plasma volume depletion, which should be continuously corrected by appropriate fluid and electrolyte replacement therapy 2. It is recommended to avoid tube feeding in patients on high doses of pressors until blood pressure and tissue perfusion are maintained without therapy and fluid volume requirements are met 2.

From the Research

Tube Feeding in Patients on High-Dose Pressors

• The use of high-dose pressors in critically ill patients can potentially affect the safety and tolerance of enteral nutrition (EN) 3, 4.
• Studies have shown that EN can be safely initiated in patients receiving vasopressors, but the decision to proceed with EN should be made on a case-by-case basis, taking into account the patient's hemodynamic stability and gastrointestinal function 5, 4.
• The risk of bowel ischemia and gastrointestinal intolerance is a concern in patients receiving vasopressors, but research suggests that EN is generally well tolerated in these patients 4.
• High-dose norepinephrine treatment can be associated with a poor outcome due to excessive vasoconstriction, and the decision to initiate EN should consider the patient's overall clinical condition and the potential risks and benefits of EN 6.

Considerations for Tube Feeding

• The patient's hemodynamic stability and gastrointestinal function should be carefully evaluated before initiating EN 3, 4.
• The risk of bowel ischemia and gastrointestinal intolerance should be monitored closely in patients receiving vasopressors and EN 4.
• The decision to initiate EN should be made on a case-by-case basis, taking into account the patient's individual needs and clinical condition 5, 4.
• The use of high-dose pressors can be a marker of severe disease, and the potential benefits and risks of EN should be carefully weighed in these patients 6.