1. ENS Interactions with Supportive Care

Mechanical ventilation and vasopressor therapy can increase aspiration risk and impair gut perfusion. Optimizing ventilator settings and circulatory support enhances enteral nutrition (EN) safety.

A. Mechanical Ventilation and Aspiration Risk

• Head‐of‐Bed Elevation: Maintain 30°–45° elevation to reduce reflux and aspiration. Reassess compliance daily and document in the nursing flow sheet.
• Feeding–Ventilator Synchrony: In assist‐control modes, timing feeding to positive pressure phases may promote gastric emptying. Consider continuous rather than bolus delivery in unstable patients.
• Ventilator‐Associated Pneumonia (VAP) Prevention: Implement a VAP bundle including oral hygiene with 0.12% chlorhexidine rinse twice daily, use of subglottic secretion drainage endotracheal tubes when available, and daily sedation interruption to enable spontaneous breathing trials.

B. Hemodynamic Support

Vasopressors at moderate doses preserve gut mucosal perfusion, but high‐dose catecholamines risk splanchnic ischemia. Initiate EN when circulatory parameters stabilize.

• Vasopressor Effects on Gut Perfusion: Norepinephrine at doses ≤0.1–0.2 µg/kg/min is generally considered safe and preserves microcirculation. Dopamine >8 µg/kg/min and high‐dose epinephrine may shunt blood flow away from the mesenteric bed.
• Perfusion Thresholds for EN Initiation: Aim for a mean arterial pressure (MAP) ≥60 mm Hg on a stable or decreasing vasopressor dose. A cardiac index >2.2 L/min/m² and central venous O₂ saturation ≥70% correlate with adequate splanchnic flow. Avoid initiating full‐volume EN if MAP is <60 mm Hg or vasopressor requirements are escalating.

2. ICU‐Related Complication Prevention

Pharmacologic prophylaxis for venous thromboembolism (VTE) and stress ulcers, along with strict infection control, are critical in EN recipients to reduce morbidity and mortality.

A. VTE Prophylaxis Pharmacotherapy

B. Stress‐Related Mucosal Bleeding Prophylaxis

C. Infection Control

• Tube‐Related Infection Prevention: Maintain aseptic handling of feeding ports and perform daily site inspection. Flush tubes before and after feeds and medication doses with 20–30 mL sterile water. Use closed‐system feeding sets and change per manufacturer guidelines.
• Antibiotic Stewardship: Culture suspected infections (e.g., site exudate, bloodstream) before starting antibiotics. Tailor empiric coverage for skin flora (MSSA/MRSA) based on local antibiograms. Narrow therapy promptly based on culture results; a typical duration is 5–7 days for uncomplicated site infections.

3. Management of Iatrogenic ENS Complications

Early identification and protocolized management of refeeding syndrome and tube occlusions limit morbidity in malnourished and EN‐dependent patients.

A. Refeeding Syndrome

This life-threatening condition is caused by rapid re-feeding in severely malnourished patients. A protocolized approach is essential for prevention.

B. Tube‐Related Infections and Occlusions

• Diagnostic Criteria and Therapy: Local signs include erythema, tenderness, and purulence; systemic signs include fever or leukocytosis. Obtain wound or blood cultures and start empiric anti‐staphylococcal therapy (e.g., cefazolin, or vancomycin if MRSA risk is high).
• Tube Patency Maintenance: Routinely flush with 20–30 mL of water before and after each intervention. For resistant occlusions, consider an enzymatic declogging agent (e.g., pancreatic enzyme solution) or a carbonated water flush. Always favor liquid medication formulations and avoid crushing sustained‐release or enteric-coated tablets.

4. Multidisciplinary Goals-of-Care

Time‐limited trials and structured family meetings ensure that extended or invasive enteral nutrition aligns with patient values and prognosis.

A. Prolonged ENS and Ethical Considerations

• Time‐Limited Trials: When the benefit of EN is uncertain, establish a trial duration (e.g., 7–14 days) with clear clinical endpoints (e.g., ability to wean from ventilator, improvement in functional status) to guide decisions about continuation.
• Proportionality: Continuously balance the nutritional benefit of EN against its burdens (e.g., aspiration risk, discomfort, catheter complications). When the prognosis is poor and burdens outweigh benefits, the goals of nutrition should shift to comfort-focused feeding.

B. Family and Care Team Communication

• Early Surrogate Involvement: Engage with family or designated surrogates early to clarify the patient’s values, goals, and what they would consider an acceptable quality of life and trade-offs.
• Structured Interdisciplinary Meetings: Regularly scheduled meetings that include pharmacy, nutrition, nursing, and palliative care are essential. Reevaluate the goals of EN every 7–10 days or whenever a major clinical change occurs.

5. Pharmacotherapy Details

A deeper dive into the pharmacology of supportive care agents used in patients receiving enteral nutrition.

A. VTE Prophylaxis

• Mechanisms of Action: Unfractionated heparin (UFH) potentiates antithrombin III, leading to the inhibition of both thrombin (Factor IIa) and Factor Xa. Low-molecular-weight heparin (LMWH) has a greater affinity for inhibiting Factor Xa.
• Indications and Agent Selection: Prophylaxis is indicated for nearly all critically ill patients due to risk factors like immobilization, sepsis, and central venous catheters. LMWH is generally preferred for its predictable kinetics and lower risk of HIT in patients with stable renal function. UFH is favored in patients with severe renal impairment (CrCl <30 mL/min), high bleeding risk, or anticipated invasive procedures due to its short half-life and reversibility.

B. Stress Ulcer Prophylaxis (SUP)

• Mechanisms of Action: Proton pump inhibitors (PPIs) provide profound acid suppression by irreversibly binding to the H⁺/K⁺ ATPase pump on gastric parietal cells. Histamine-2 receptor antagonists (H2RAs) competitively block the H2 receptor, reducing acid secretion.
• Adverse Warnings and Pearls: The primary concern with PPIs is an association with increased risk of hospital-acquired pneumonia and Clostridioides difficile infection due to profound acid suppression. This has led to a push for risk-based SUP strategies rather than universal prescribing. De-escalate or discontinue SUP as soon as the primary risk factors (e.g., mechanical ventilation >48h, coagulopathy) have resolved.

C. Antimicrobials for Tube-Related Infections

• Empiric Spectrum and Dosing: Initial therapy should target common skin flora. For non-purulent cellulitis without systemic signs, an anti-staphylococcal agent like cefazolin (1–2 g IV q8h) is appropriate. If MRSA risk factors are present (e.g., prior colonization, high local prevalence) or the infection is purulent, vancomycin (dosed per pharmacy protocol) should be used.
• Monitoring and Stewardship: De-escalate therapy based on culture and sensitivity results. Avoid broad-spectrum agents like piperacillin-tazobactam or carbapenems for simple cellulitis unless there is a high suspicion for polymicrobial or resistant gram-negative infection. A duration of 5–7 days is sufficient for most uncomplicated infections.