Total Parenteral Nutrition (TPN): Indications, Access & Risks

TPN delivers complete nutrition intravenously when the GI tract cannot be used, is insufficient, or must be rested.

Indications

• GI failure: Short bowel syndrome, high-output fistula, complete obstruction, severe malabsorption (Crohn's, radiation enteritis).
• Perioperative: Major abdominal surgery, prolonged NPO >7-10 days (malnourished: >5-7 days).
• Critical illness: Inability to tolerate EN (enteric nutrition) after 7-10 days.
• Pediatric: NEC, gastroschisis, intestinal atresia.

Access

• Central venous catheter (CVC): PICC, tunneled (Hickman), implanted port. Required for high osmolarity (>900 mOsm/L).
• Peripheral (PPN): Low osmolarity (<900), short-term (<2 weeks), supplemental only.

Composition

• Dextrose (carb), amino acids (protein), lipid emulsion (fat), electrolytes, vitamins, trace elements.
• Customized: Calorie/nitrogen ratio, fluid restriction, renal/hepatic formulas.

Complications

• Infectious: CLABSI (central line-associated bloodstream infection) — #1 risk.
• Metabolic: Hyperglycemia, refeeding syndrome (hypophosphatemia), electrolyte shifts, hepatic steatosis/cholestasis.
• Mechanical: Pneumothorax, thrombosis, catheter malposition.
• Long-term: IFALD (intestinal failure-associated liver disease), metabolic bone disease.

Monitoring

• Daily: Glucose, electrolytes, fluid balance, weight, I/O.
• Weekly: LFTs, triglycerides, prealbumin, trace elements.
• Line care: Maximal barrier, chlorhexidine, daily necessity review.

TPN is life-saving but high-risk. **Enteral nutrition (tube feeding) is preferred whenever gut works.** Multidisciplinary nutrition support teams optimize outcomes.