Total Parenteral Nutrition in ICU
Introduction to TPN
- The American Society for Parenteral and Enteral Nutrition recommends initiating TPN within 24-48 hours in critically ill ICU patients who cannot receive enteral nutrition, but only after attempting enteral feeding first, as enteral nutrition significantly reduces infectious complications and mortality compared to TPN 1, 2
When to Initiate TPN
- Start TPN within 24-48 hours if enteral nutrition cannot be initiated or is contraindicated in patients not expected to resume normal oral nutrition within 3 days, according to the Clinical Nutrition guidelines 1, 3
- These guidelines apply specifically to ICU patients with organ failure and expected ICU stay longer than 3 days, as stated by the Clinical Nutrition society 1, 4
Critical Timing Considerations
- Enteral nutrition must be attempted first within 48 hours of ICU admission in hemodynamically stable patients with functioning gastrointestinal tracts, as recommended by the Clinical Nutrition society 5, 2
- Early enteral nutrition reduces infectious complications by 50% compared to early TPN and shortens both ICU and hospital stays, with a relative risk of 0.50 and a confidence interval of 0.37-0.67 2
TPN Composition and Dosing
- The energy requirements for acute phase patients should be 20-25 kcal/kg/day to avoid overfeeding, according to the Clinical Nutrition guidelines 1, 6
- The protein target should be 1.3-1.5 g/kg ideal body weight/day with a balanced amino acid mixture, as recommended by the Clinical Nutrition society 1, 7
Administration Route
- Central venous access is required for high osmolarity TPN mixtures designed to cover full nutritional needs, as stated by the Clinical Nutrition society 1, 4, 8
Critical Pitfalls to Avoid
- Hyperglycemia is a major risk factor that increases mortality and infectious complications in critically ill patients, and blood glucose should be maintained between 4.5-10 mmol/L, according to the Clinical Nutrition guidelines 1, 6
- Energy deficits correlate strongly with infectious complications, duration of mechanical ventilation, and ICU length of stay, as reported by the Clinical Nutrition society 1, 4