Total Parenteral Nutrition (TPN) - Formula, Guidelines, Indications

Total Parenteral Nutrition (TPN) is the administration of food supplements via routes other than the enteral route. It is used commonly in critically ill patients and those with extensive gastrointestinal surgery or diseases such as Crohn's disease or ulcerative colitis.

Indications of Total parenteral nutrition (TPN):

Nutritional supplementation:
- Kabiven, Perikabiven:
  - It is indicated as a source of calories, protein, electrolytes, and essential fatty acids for adult patients requiring parenteral nutrition when oral or enteral nutrition is not possible, insufficient, or contraindicated, prevention of essential fatty acid deficiency or treatment of negative nitrogen balance in adult patients.
- Limitations of use:
  - These fixed-content formulations are not recommended for use in children <2 years of age, including preterm infants, because they do not meet nutritional requirements for this age group.
Guideline recommendations:
- According to the American Society for Parenteral and Enteral Nutrition (ASPEN), parenteral nutrition has been shown to be effective in perioperative nutrition in patients with moderate to severe malnutrition, acute exacerbations of Crohn disease, GI fistulas, extreme short bowel syndrome, critically ill patients who cannot take in oral feeding for prolonged periods of time, or severe acute necrotizing pancreatitis.
- The Society of Critical Care Medicine (SCCM) and ASPEN guidelines for critically ill patients recommend that in high-risk patients or severe malnutrition, it should be given as soon as possible after ICU admission when enteral nutrition is not feasible.
- In critically ill patients at either low or high nutrition risk who are unable to meet >60% of energy and protein requirements by enteral route alone, parenteral nutrition may be considered after 7 to 10 days.
- The use of standardized (or fixed) commercially available solutions shows no advantage in the clinical outcome of the critically ill patient population, therefore these are not recommended.

Total parenteral nutrition (TPN) Dose in Adults

TPN for Nutritional supplementation:

Fixed-combination solutions:

Note:

Dosage should be individualized based on patient status. These products contain a fixed combination of amino acids, dextrose, lipids, and electrolytes.
Therapy should be continued depending on patient status. Fluid, electrolyte, or acid-base disorders needs to be corrected before infusion.
Also refer to the American Society for Parenteral and Enteral Nutrition for more detailed information.
- Kabiven (central line use only):
  - 19 to 38 mL/kg/day infused over 12 to 24 hours.
  - The maximum daily dose: 40 mL/kg/day.
- Perikabiven (peripheral or central line):
  - 27 to 40 mL/kg/day infused over 12 to 24 hours.
  - The maximum daily dose: 40 mL/kg/day.
TPN dosage adjustment for increased serum triglycerides:
- If triglycerides >400 mg/dL, the infusion should be stopped and monitoring is needed.
- Once triglycerides are <400 mg/dL, the infusion should be restarted at a lower rate with slow increments. Use is contraindicated with triglycerides >1,000 g/dL.
Equations and recommendations for use when designing patient-specific parenteral nutrition :
- Total calories: Calculate using Harris-Benedict equation (Harris 1919) (constants and coefficients rounded to the nearest hundredth place) or base on stress level as indicated below:
- Harris-Benedict Equation (BEE):
  - Females: 655.1 + [(9.56 x W) + (1.85 x H) - (4.68 x A)]
  - Males: 66.47 + [(13.75 x W) + (5 x H) - (6.76 x A)]
  - W = actual body weight in kg; H = height in cm; A = age in years
- To determine total calories needed (based on total energy expenditure [TEE]) use the following equation:
  - TEE = BEE + [BEE x (Activity Factor - 1)] + [BEE x (Stress Factor - 1)]
  - Activity factor = 1.2 sedentary, 1.3 normal activity.
  - Stress factor:
    - 1.3 for sepsis, trauma, stressed, or surgical patients;
    - 1.5 for underweight (to promote weight gain);
    - up to 2 for severe burn patients;
    - 1.5 to 2 for acute renal failure;
    - 1.1 to 1.2 for chronic renal failure.
  - Stress level:
    - Normal/mild stress level: 20 to 25 kcal/kg/day.
    - Moderate stress level: 25 to 30 kcal/kg/day.
    - Severe stress level: 30 to 35 kcal/kg/day.

TPN for pregnant women in second or third trimester: Add an additional 300 kcal/day (ASPEN 2002)

Note:

Indirect calorimetry is helpful in determining energy requirements in critically ill patients.
A published predictive equation or a simple weight-based equation (25 to 50 kcal/kg/day [use dry or usual body weight]) can be used if indirect calorimetry is not available.
If patient is obese, use 11 to 14 kcal/kg/day (use actual body weight) for BMI of 30 to 50 kg/m and 22 to 25 kcal/kg/day for BMI >50 kg/m .
Re-evaluation of energy expenditure should be done more than once per week while optimizing energy and protein intake.
Fluid: 30 to 40 mL/kg.
Carbohydrate (dextrose): 45% to 65% of total calories.
Maximum rate: 7 mg/kg/minute.

Note: Doses rarely exceed 5 mg/kg/minute due to an increased risk of hyperglycemia.

Protein (amino acids):
- Maintenance: 0.8 to 1 g/kg/day.
- Critically ill: 1.2 to 2 g/kg/day.
- Sepsis: 2 to 2 g/kg/day.
Obese (critically ill):
- BMI 30 to 40 kg/m²: 2 g/kg/day using IBW.
- BMI >40 kg/m²: 2.5 g/kg/day using IBW.
- Burn patients (severe): 5 to 2 g/kg/day, increase protein until significant wound healing achieved.
- Solid-organ transplant: Perioperative: 1.5 to 2 g/kg/day.
Renal failure:
- Acute (severely malnourished or hypercatabolic): 5 to 1.8 g/kg/day.
- Chronic Renal failure, with dialysis: 2 to 1.3 g/kg/day.
- Chronic Renal failure, without dialysis: 6 to 0.8 g/kg/day.
- Continuous renal replacement therapy or frequent hemodialysis: ≥1 g/kg/day (up to 2.5 g/kg/day).
Pregnant women in second or third trimester: Add an additional 10 to 14 g/day:
- Fat:
  - Initial: 10% to 35% of total calories.
  - Maximum: 60% of total calories or 2.5 g/kg/day).
  - If triglyceride levels <400 mg/dL, IV lipids are safe to use in pancreatitis.
  - Electrolytes, minerals, vitamins, and trace elements: Refer to local policies and ASPEN guidelines.

Note: Triglyceride monitoring is necessary while receiving intralipids.

TPN use in Children:

Refer to adult dosing.

TPN Dose in pregnancy and lactation:

Due to severe malnutrition during pregnancy, congenital malformations and intrauterine growth restriction can result in preterm birth, low births, and perinatal mortality.
You may need to consume more calories or protein.
Some cases of TPN can be used for long-term treatment during pregnancy.
For women who are unable to maintain their weight due to nausea/vomiting during pregnancy, it is better to take enteral nutrition than total parenteral.

TPN use during breastfeeding:

The same nutrients, including dextrose and amino acids, are found in regular food. The clinical condition of the patient is a factor in determining the clearance of lipids.
The manufacturer of the premixed product stated that the decision to breastfeed during treatment depends on the benefits and risks of breastfeeding for the infant as well as the benefits to the mother.

TPN Dose adjustment in renal disease:

Kabiven, Perikabiven:

No dosage adjustments are necessary for renal impairment. Severe fluid or electrolyte imbalances should be corrected before therapy. Close monitoring of electrolytes and administered volume adjustment are necessary.
Supplement protein as indicated for patients with acute or chronic renal impairment or those requiring frequent dialysis or CRRT.
The additional amino acid solution may be added to the premixed solutions or infused separately.

TPN Dose adjustment in liver disease:

There is no dosage adjustment provided in the manufacturer's labeling, use with caution.

How to administer TPN?

TPN is ideally administered intravenously.
TPN formulation with osmolality less than 900 mEq/L may also be administered via a peripheral IV line, however, continuous monitoring for fluid extravasation is important.
It is usually administered as a slow intravenous infusion.
Rapid discontinuation of the infusion should be avoided because of the increased risk of hypoglycemia.
It is also important to avoid infusion via Y-site administration, however, where necessary, Y-site compatibility should be checked before it is infused.
Y-site administration with Ceftriaxone should be avoided. All the lines should be flushed before and after the administration of the TPN infusion.

Kabiven is infused over 12 - 24 hours via a central line at a rate not exceeding 2.6 ml/kg/hour.

This maximum rate of infusion corresponds to:

dextrose @ 0.25 gms/kg/hour (dextrose is the rate-limiting nutrient and the maximum rate of infusion should not exceed infusing dextrose at greater than 0.25 gm/kg/hour)
lipids @ 0.1 gm/kg/hour
amino acids @0.09 gm/kg/hour

Perikabiven is infused over 12 to 24 hours. The maximum infusion rate should not exceed 3.7 ml/kg/hour. This maximum rate of infusion corresponds to:

amino acids 0.09 g/kg/hour;
dextrose 0.25 g/kg/hour (dextrose infusion is the rate-limiting and the rate should not exceed 0.25 gm/kg/hour)
lipids 0.13 g/kg/hour

It is important to note that TPN formulations are vesicant and extravasation may result in skin necrosis. appropriate measures should be taken if extravasation occurs, including:

Aspiration of the fluid via the same cannula
raising the hand
application of dry and cold compresses
administration of hyaluronidase via the same cannula, followed by removal of the cannula or around the site in a clockwise manner.
May also apply topical GTN ointment.

MOA of TPN:

TPN is a combination of electrolytes, carbohydrates primarily Dextrose, amino acid and fatty acids that are administered intravenously after the patient's daily dose and rate have been calculated.