Starting Enteral Nutrition in Unconscious Patients
Begin continuous enteral feeding at 20 mL/hour in unconscious patients with a functioning gastrointestinal tract, then increase by 25 mL/hour every 8 hours as tolerated until nutritional goals are reached. 1
Initial Rate Selection
- Start at 20 mL/hour for most unconscious critically ill patients using continuous pump-assisted feeding 1
- Well-nourished patients (adequate nutrition in the preceding week) may start at up to 50 mL/hour 1
- Very malnourished or high-risk patients should start at <10 kcal/kg/day (approximately 10-15 mL/hour of standard 1 kcal/mL formula) to prevent refeeding syndrome 2
Rate Advancement Protocol
Increase the infusion rate by 25 mL/hour every 8 hours provided the patient tolerates feeding without complications 1. This stepwise approach typically achieves nutritional goals by day 5-7 1.
Example Advancement Schedule:
- Hours 0-8: 20 mL/hour
- Hours 8-16: 45 mL/hour (increase +25)
- Hours 16-24: 70 mL/hour (increase +25)
- Continue: +25 mL/hour every 8 hours until goal rate achieved 1
Tolerance Monitoring Before Each Rate Increase
Check these parameters before advancing the rate 1:
- Gastric residual volume (GRV): Hold advancement if >200 mL 3, 1
- Clinical signs: Abdominal distension, vomiting, or diarrhea warrant pausing advancement 1
- Electrolytes: Monitor sodium, potassium, magnesium, calcium, and phosphate closely in the first 3-5 days 3, 1
Critical GRV Thresholds:
- <200 mL: Continue feeding without modification 3
- >200 mL: Review feeding policy, consider prokinetics or rate reduction 3
- >500 mL per 6 hours: Delay further enteral nutrition, consider post-pyloric (jejunal) feeding 4, 1
Route-Specific Considerations
Nasogastric/Gastric Feeding:
- Preferred for unconscious patients as it allows higher infusion rates and faster advancement 1
- Continuous pump feeding is mandatory initially 4, 1
- Check GRV every 4 hours in patients with uncertain gastrointestinal motility 3, 1
- Flush tube with water every 4 hours during continuous feeding 1, 5
Jejunal/Post-Pyloric Feeding:
- Start at 10 mL/hour of isotonic saline for first 24 hours, then transition to formula with slower increments 4, 1
- Never use bolus feeding into the jejunum—continuous infusion only to prevent dumping syndrome 4, 1
- Consider this route if gastric residuals remain persistently elevated 1
Safety Measures for Unconscious Patients
- Maintain head-of-bed elevation ≥30° continuously during feeding and for 30 minutes after to reduce aspiration risk 3, 1
- Confirm tube placement before initiating feeds and regularly thereafter 5
- Avoid overnight continuous feeding once the patient stabilizes, as this increases aspiration risk 4
- Transition to intermittent feeding as soon as clinically appropriate 4, 1
When to Initiate Feeding in Unconscious Patients
Start early enteral nutrition (EEN) within 24-48 hours in unconscious patients with traumatic brain injury, stroke (ischemic or hemorrhagic), or spinal cord injury once hemodynamic stability is achieved 4.
Contraindications to Immediate Feeding:
- Uncontrolled shock with inadequate tissue perfusion (e.g., norepinephrine >1 μg/kg/min with persistent hyperlactatemia) 4
- Active upper GI bleeding (wait until bleeding stops) 4
- Bowel ischemia or obstruction 4
- Abdominal compartment syndrome 4
- Gastric aspirate >500 mL per 6 hours 4
Common Pitfalls to Avoid
- Do not delay feeding solely because of absent bowel sounds—this is not a contraindication unless bowel ischemia or obstruction is suspected 4
- Do not delay feeding for neuromuscular blocking agents, prone positioning, or therapeutic hypothermia (use low-dose feeding and advance after rewarming) 4
- Do not use diluted feeds at initiation—standard full-strength formula is appropriate from the start unless refeeding syndrome is a concern 4
- Do not advance rates if GRV exceeds 200 mL without first addressing the cause with prokinetics or feeding strategy modification 3, 1