Enteral and Parenteral Nutrition in Critically Ill Patients: PowerPoint Presentation
Slide 1: Core Principle
Early enteral nutrition (EN) within 48 hours is preferred over early parenteral nutrition (PN) in critically ill patients, as it reduces infectious complications by 50% and improves clinical outcomes. 1, 2, 3
Slide 2: Definition and Timing
What is Early Enteral Nutrition?
- EN initiated within 24-48 hours of ICU admission in hemodynamically stable patients with functioning gastrointestinal tracts 1, 2, 3
- Independent of type or amount of feeding 1
Evidence for Early EN
- Reduces infectious complications (RR 0.50,95% CI 0.37-0.67) compared to delayed EN 2, 3
- Shorter ICU stays (RR -0.73, p = 0.01) and hospital stays (RR -1.23, p = 0.002) versus PN 3
- Reduced infectious episodes with EN versus TPN (RR 0.64,95% CI 0.48-0.87) 3
Slide 3: When to START Enteral Nutrition
Initiate EN in These Situations:
- Controlled shock with hemodynamic stability and adequate tissue perfusion 1
- Stable hypoxemia with compensated or permissive hypercapnia/acidosis 1
- Patients on neuromuscular blocking agents (do not delay EN solely for this reason) 1
- Therapeutic hypothermia (start low dose, increase after rewarming) 1
- Severe acute pancreatitis, traumatic brain injury, GI surgery, abdominal trauma 1
Slide 4: When to DELAY Enteral Nutrition
Absolute Contraindications:
- Uncontrolled shock with very high vasopressor doses (e.g., norepinephrine >1 μg/kg/min) and persistent hyperlactatemia or end-organ hypoperfusion 1
- Uncontrolled life-threatening hypoxemia, hypercapnia, or acidosis 1
- Uncontrolled upper GI bleeding 1
- Bowel ischemia 1
- Bowel obstruction 1
- Abdominal compartment syndrome 1
- Gastric aspirate >500 ml/6 hours 1
- High-output fistula without distal feeding access 1
Slide 5: How to Initiate and Advance EN
Starting Protocol:
- Begin at 10-20 ml/hour while carefully monitoring abdominal/GI symptoms 1
- Increase slowly once symptoms resolve and no new symptoms develop 1
- Do NOT increase if intolerance occurs (pain, distension, rising intra-abdominal pressure) 1
Monitoring During EN:
- Use prokinetics and/or postpyloric feeding for gastric retention without other abdominal symptoms 1
- Measure intra-abdominal pressure (IAP) in patients with severe abdominal pathology, hypoperfusion, or fluid overload 1
- Consider postpyloric feeding for patients with diminished consciousness and inadequate swallowing to prevent aspiration 1
Slide 6: Energy and Protein Targets
Acute Phase (First 72-96 Hours):
- Energy: 20-25 kcal/kg/day (avoid exceeding actual energy expenditure) 1, 2, 3
- Protein: 1.3-1.5 g/kg ideal body weight/day 2
- Do NOT aim for full energy target with early EN—hypocaloric EN is safe, while overfeeding is harmful 1
Recovery/Anabolic Phase:
Slide 7: Role of Parenteral Nutrition
When to Consider PN:
- EN is contraindicated or impossible 3
- EN fails to meet nutritional requirements after 3-7 days, especially in severely malnourished patients 3
Supplemental PN (SPN + EN):
- Decreases nosocomial infections (RR 0.733, p = 0.032) compared to EN alone 4
- Reduces ICU mortality (RR 0.569, p = 0.030) 4
- Improves energy and protein delivery when EN alone is inadequate 5, 4
- No significant difference in hospital stay, hospital mortality, or ventilator days 4
Caution with PN:
- Early PN alone (without EN) is NOT recommended as first-line therapy 1, 3
- PN associated with higher infectious complications and hyperglycemia risk versus EN 2, 3
- Implement with caution to avoid overfeeding 3
Slide 8: Glycemic Control
Target Blood Glucose:
- Maintain 140-180 mg/dL (7.8-10 mmol/L) 2
- Avoid both hypoglycemia and hyperglycemia, as both increase morbidity and mortality 2
Slide 9: Clinical Vignette #1
Case: Septic Shock Patient
62-year-old male with septic shock from pneumonia, requiring norepinephrine 0.3 μg/kg/min, lactate 2.8 mmol/L, MAP 68 mmHg, mechanically ventilated.
Management:
- Initiate EN within 24-48 hours as shock is controlled (norepinephrine <1 μg/kg/min, lactate normalizing) 1
- Start at 10-20 ml/hour 1
- Target 20-25 kcal/kg/day during acute phase 2, 3
- Monitor for gastric retention and abdominal symptoms 1
- Do NOT start PN unless EN fails after 3-7 days 3
Slide 10: Clinical Vignette #2
Case: Severe Acute Pancreatitis
48-year-old female with severe acute pancreatitis, APACHE II score 18, no shock, mechanically ventilated for respiratory failure.
Management:
- Initiate EN within 48 hours (evidence shows reduced infectious complications in pancreatitis) 1
- Start at 10-20 ml/hour 1
- Advance slowly while monitoring for abdominal pain, distension, rising IAP 1
- Consider postpyloric feeding if gastric intolerance develops 1
- Target hypocaloric feeding (20-25 kcal/kg/day) initially 1, 2, 3
Slide 11: Clinical Vignette #3
Case: Refractory Shock with Bowel Ischemia Concern
55-year-old male with distributive shock requiring norepinephrine 1.5 μg/kg/min, lactate 6.2 mmol/L, abdominal distension, bloody nasogastric aspirate.
Management:
- DELAY EN due to uncontrolled shock (norepinephrine >1 μg/kg/min), persistent hyperlactatemia, and concern for bowel ischemia 1
- Do NOT initiate PN early (no mortality benefit, may worsen outcomes) 1, 3, 6
- Reassess once shock controlled and vasopressor requirements decrease 1
- Start low-dose EN (10-20 ml/hour) once norepinephrine <1 μg/kg/min and lactate trending down 1
Slide 12: Clinical Vignette #4
Case: Traumatic Brain Injury
32-year-old male with severe TBI (GCS 6), intubated, hemodynamically stable, ICP 18 mmHg on sedation and osmotic therapy.
Management:
- Initiate EN within 48 hours (evidence shows reduced infectious complications in TBI) 1
- Start at 10-20 ml/hour 1
- Consider postpyloric feeding due to diminished consciousness and aspiration risk 1
- Target 20-25 kcal/kg/day during acute phase 2, 3
- Do NOT delay EN for neuromuscular blockade if used 1
Slide 13: Clinical Vignette #5
Case: Post-Operative Abdominal Surgery with EN Intolerance
68-year-old female, post-exploratory laparotomy for perforated diverticulitis, EN started day 2, now day 5 with persistent high gastric residuals (400 ml q6h), receiving only 40% of caloric goal.
Management:
- Use prokinetics (metoclopramide or erythromycin) in protocolized manner 1
- Switch to postpyloric feeding if gastric retention persists 1
- Consider supplemental PN after day 7 if EN continues to provide <60% of requirements, especially if malnourished 3, 4
- Monitor for refeeding syndrome when initiating PN (electrolytes, phosphorus) 3
- SPN + EN may reduce nosocomial infections and ICU mortality versus EN alone 4
Slide 14: Common Pitfalls to Avoid
Critical Errors in ICU Nutrition:
- Delaying nutritional support beyond 48 hours in stable patients (increases morbidity) 2, 3, 7
- Overfeeding during acute phase (>25 kcal/kg/day worsens outcomes) 1, 2, 3
- Starting early PN instead of EN when GI tract is functional (increases infections) 1, 3
- Abandoning EN for high gastric residuals without trying prokinetics or postpyloric feeding 1, 3
- Ignoring refeeding syndrome risk when starting nutrition in malnourished patients 3
- Feeding during uncontrolled shock (risk of bowel ischemia) 1
- Aiming for full caloric goals immediately (hypocaloric EN is safer early) 1
Slide 15: Practical Algorithm for ICU Nutrition
Step-by-Step Approach:
1. Assess within 24 hours of ICU admission:
- Is GI tract functioning? 3
- Is patient hemodynamically stable? 1
- Any absolute contraindications to EN? 1
2. If YES to functioning GI tract and stable hemodynamics:
3. Monitor and advance:
- Increase rate slowly if tolerating 1
- Use prokinetics for gastric retention 1
- Consider postpyloric feeding if needed 1
4. If EN inadequate by day 3-7:
5. If absolute contraindications exist: