What are the guidelines for total parenteral nutrition (TPN) transfusion in critically ill adult or pediatric patients with high metabolic demand?

TPN Administration Guidelines

Total parenteral nutrition should be administered via central venous access using cyclic infusion over 10-14 hours at rates of 80-125 mL/hour, providing 25 kcal/kg/day initially in ICU patients, with amino acids at 1.3-1.5 g/kg/day and glucose not exceeding 5 mg/kg/min to prevent metabolic complications. 1, 2

Indications and Timing

Initiate TPN within 24-48 hours if enteral nutrition is contraindicated or not feasible, particularly in patients not expected to resume normal nutrition within 3 days. 1

• In critically ill patients with high nutritional risk, start TPN after 3 days if enteral feeding remains insufficient 3
• For low nutritional risk patients, withhold TPN for the first 7 days unless enteral access is impossible 3
• Delay TPN initiation until hemodynamic stability is achieved (vasopressor requirements <1 μg/kg/min norepinephrine) 3
• Starvation or underfeeding in ICU patients is associated with increased morbidity and mortality, making timely intervention critical 1

Venous Access and Route Selection

Use central venous access (subclavian or internal jugular vein) for TPN solutions with osmolarity >850 mOsmol/L, which is standard for full nutritional support. 1, 3, 2

• Tunneled central catheters are required for long-term parenteral nutrition 1
• Single-lumen catheters are preferred over multi-lumen to minimize infection risk 1
• Peripheral access is only appropriate for low osmolarity solutions (<850 mOsmol/L) providing partial nutrition 3
• PICC lines are intended for shorter-term use and are not recommended for home parenteral nutrition 1

Infusion Rate and Cycling Protocol

Administer TPN as cyclic infusion over 10-14 hours at 80-125 mL/hour, typically overnight, to allow daytime freedom from the infusion pump. 1, 2

• Calculate infusion rate by dividing total daily volume (typically 2-3 liters) by the intended 10-14 hour infusion duration 2
• Use infusion pumps to ensure accurate delivery and prevent complications 2
• Continuous 24-hour infusion increases risk of liver complications and should be avoided 2
• Taper infusion rates at the end of each cycle to prevent rebound hypoglycemia 2

Energy and Macronutrient Targets

Provide 25 kcal/kg/day during the acute phase, with non-protein energy ratio of approximately 60% carbohydrate and 40% lipid. 1, 4

• In the absence of indirect calorimetry, start with 25 kcal/kg/day and increase to target over 2-3 days 1
• Hypocaloric nutrition at 20-25 kcal/kg/day (approximately 50% of predicted needs) is recommended during days 1-7 to avoid harmful effects of early full feeding 3
• The non-protein energy provision should be 100-150 kcal for every gram of nitrogen 1
• Maximum glucose oxidation rate is 4-7 mg/kg/min; do not exceed 5 mg/kg/min to decrease metabolic alterations 1
• Glucose administration should not exceed 7 mg/kg/min or 10 g/kg/day to avoid hyperglycemia and complications 2

Protein/Amino Acid Requirements

Provide 1.3-1.5 g/kg/day of amino acids in critically ill patients, with optimal protein sparing effects achieved at these doses. 1

• Unstressed adult patients with normal organ function require 0.8-1.0 g/kg/day 1
• Severely traumatized patients require approximately 1.3 g/kg/day 1
• Septic patients require approximately 1.5 g/kg/day 1
• Stressed or catabolic patients may require up to 2.0 g/kg/day 1
• Include 0.2-0.4 g/kg/day of L-glutamine (0.3-0.6 g/kg/day alanyl-glutamine dipeptide) in ICU patients 1

Lipid Administration

Limit intravenous lipid to 1 g/kg/day for long-term TPN (>6 months), providing 15-30% of non-protein energy from lipids. 1

• Essential fatty acid requirement is 7-10 g daily, corresponding to 14-20 g LCT fat from soya oil 1
• For short-term use, lipids should provide approximately 40% of non-protein energy 4
• Soya-based fat should not exceed 1 g/kg/day in long-term patients to prevent chronic cholestasis and liver disease 1
• Essential fatty acid deficiency develops in 2-6 months with completely fat-free regimens 1

Glucose Management

Maintain blood glucose between 4.5-10 mmol/L (81-180 mg/dL), reducing glucose-based calories if blood sugar exceeds 180 mg/dL. 1, 3, 2

• Strict glycemic control targeting 4.5-6.1 mmol/L is associated with increased mortality and severe hypoglycemia (6.8% vs 0.5%) and is not recommended 1
• The NICE SUGAR study demonstrated increased mortality with intensive glucose control (odds ratio 1.14,95% CI 1.02-1.28) 1
• Monitor blood glucose daily during TPN infusion 2
• Insulin infusion may be required to maintain target glucose levels 1

Special Considerations for High-Risk Patients

In severely malnourished patients, start with reduced caloric loads of 15-20 kcal/kg/day and increase gradually over 3 days to prevent refeeding syndrome. 2

• Administer thiamine before glucose infusion to reduce risk of Wernicke's encephalopathy 5, 2
• Monitor phosphate, potassium, and magnesium levels closely during initiation 2
• Patients with chronic alcoholism and malnutrition are at particular risk for refeeding syndrome 1
• In acute pancreatitis, reduce energy to 15-20 non-protein kcal/kg/day if SIRS or MODS is present 1

Administration Method

Use all-in-one bag systems prepared in hospital pharmacy or by industry rather than separate containers. 1

• All-in-one bags are the least expensive PN system and reduce administration errors 1
• Separate container application significantly increases costs and risk of septic and metabolic complications 1
• PN admixtures contain more than 40 different components including water, macronutrients, electrolytes, and micronutrients 1

Monitoring Requirements

Perform daily blood glucose monitoring with target levels below 180 mg/dL, and daily electrolyte monitoring in high-risk patients during initiation. 2

• Regular inspection of central line site for signs of infection or complications is mandatory 2
• Monitor for catheter-related mechanical problems and metabolic abnormalities 6
• Meticulous catheter care is essential to minimize risk of catheter-related sepsis 1
• In patients with acute pancreatitis, pay particular attention to potassium, magnesium, phosphate, thiamine, and sodium balance 1

Critical Pitfalls to Avoid

Avoid overfeeding, which is as detrimental as underfeeding and increases risk of infectious complications, organ dysfunction, and death. 1, 2

• Do not exceed 25-35 kcal/kg/day, particularly in severely ill patients with preexisting organ failure 7
• Hyperalimentation should be avoided at acute stage of disease in any case 4
• Avoid abrupt discontinuation of TPN infusion without tapering 2
• Do not initiate TPN in hemodynamically unstable patients with uncontrolled shock 3
• Glucose administration exceeding 7 mg/kg/min increases risk of hyperglycemia, infections, and metabolic complications 2