Parenteral nutrition (TPN)

Adequate nutrients needed for optimal cell and organ function and wound repair.

Nutrition is essential to growth, healing, and vitality.

Complete intravenous parenteral nutrition provides fluids, dextrose, amino acids, lipid emulsion, electrolytes, vitamins, and minerals.

Composition of adult formulation of central venous parenteral nutrition: 1-2 liters per day, 10-25% of dextrose, 3-8% of amino acids, 2.5-5% of lipids, 40-150 mmol/L of sodium, 30-50 mmol/L of potassium, 10-30 mmol/L of phosphorus, 5-10 mmol/L of magnesium and 1.5-2.5 mmol/L of calcium.

Electrolytes are adjusted to renal function and gastrointestinal losses and other indicators to maintain serially measured serum levels in the normal range.

If a patient needs nutrition for a short time, peripheral parenteral nutrition can be provided for a few days.

Peripheral parenteral nutrition is fat based and does not contain full carbohydrates, so it provides nutrients on a temporary basis.

The major advantage of peripheral Parenteral nutrition is that it can be administered through an intravenous line and can be given continuously through the day and night or it can be cyclic.

Peripheral parenteral nutrition cannot be received at home.

Total parenteral nutrition, TPN, can provide all the types of nutrition that a patient needs.

TPN requires a central catheter line and can be given continuously or cyclic.

TPN can be received at home.

For proper monitoring of parenteral nutrition studies should include blood sugar, serum proteins, kidney and liver function tests, electrolytes,, carbon dioxide content, serum osmolarities, blood cultures, and blood ammonia levels.

Majority of data indicates that there is no improvement in the outcome of serious illness when compared to the use of enteral nutrition.

25 kcal per kg per day with 0.1 gm nitrogen per kg per day is sufficient for most patients.

Insulin and other drugs can be added to the parenteral solution.

Effects of parenteral nutrition by providing energy in the form of dextrose and lipids. essential and nonessential amino acids, essential fatty acids vitamins, minerals and electrolytes.

Parenteral nutrition supports vital cellular and organ functions, promotes immunity, promotes tissue repair and regeneration, supports protein production and supports skeletal, cardiac and respiratory muscles.

Indications for use include critically ill patients with small bowel resection, with or without colonic resection, and proximal high-output fistulae or perforated small intestine.

Indications for use when enteral nutrition may be contraindicated or or not tolerated such as 5-7 days of severe diarrhea, vomiting, abdominal distension, partial or complete bowel obstruction, gastrointestinal bleeding or hemodynamic instability.

Use of parenteral nutrition generally discouraged when adequate gastrointestinal function is present with access to enteral feedings, intolerance to fluid loads exist, the presence of severe hyperglycemia, the presence of severe electrolyte abnormalities and a situation where its use is likely to be needed for no more than 5-7 days.

Enteral nutrition contraindicated with diffuse peritonitis, intestinal obstruction, early stages of short bowel syndrome, paralytic ileus, intractable vomiting, severe gastrointestinal bleeding, severe diarrhea and malabsorption syndromes.

Relative contraindications to use enteral nutrition include pancreatitis and enterocutaneous fistulae.

Most parenteral infusions provide excess dextrose and caloric content with findings that hyperglycemia associated with increased morbidity and mortality.

Glutamine supplemented parenteral nutrition reduces infection and mortality in critically ill patients.

Blood sugars exceeding 180 mg per dL in the ICU setting associated with increased death rates and increased complications (NICE-SUGAR Study investigators

Enteral nutrition use, as compared to parenteral nutrition in ICU patients is pref2241ed when patients are able to do so.

A meta-analysis of intention-to-treat trials comparing enteral with parenteral nutrition in critically ill patients, revealed a reduction in mortality among patients receiving parenteral nutrition (Simpson F).

In the above studies, if enteral nutrition was started within 24 hours of ICU admission no significant benefit was apparent for parenteral nutrition, and significant increases of infection occured in the parenteral nutrition group.(Simpson F).

13 randomized trials revealed that enteral nutrition in critically ill adult patients was associated with significant reductions in infectious complications compared to parenteral nutrition without a difference in mortality (Gramlich L).

Male predominance in parenteral nutrition-associated cholestasis in newborn surgical patients.

Associated cholestasis is a complication seen in 7.4-84% of parenterally fed infants.

Long-term treatment often associated with complications with survival rates at 3 and 5 years of 70% and 63%, respectively.

The most serious complication of its use is liver disease, with half of adults and children developing this problem with continuous therapy.

Liver toxicity can be reversed by cycling fluid treatment or by lowering the lipid or dextrose concentrations, by the use of oral feedings, or adding antibiotics.

The development of liver disease it may lead to death within 1 year, if hepatic changes persist.

Common complications include: central catheter thrombosis, catheter-related sepsis, electrolyte abnormalities, hydration changes, and renal stones.

May be administered by central or peripheral vein.

20-25 kcal per kg of body weight is total caloric target range for most adult patients in the ICU.

Peripheral vein administration must be in large amounts as concentrated fluids can cause chemical phlebitis.

In situations where fluid restriction is necessary such as renal, hepatic or cardiac dysfunction the large amount of fluid volumes needed for peripheral vein nutrition precludes this mode of delivery, and central venous delivery is preferable.

Catheters placed for parenteral nutrition should be reserved for such fluids and should not be used for other purposes, like drawing blood or the administration of medications.

The catheter used for parenteral nutrition must be maintained with sterile techniques.

Parenteral fluids are prepared under sterile conditions and should be prepared daily to maintain biochemical activity and prevent bacterial contamination.

Parenteral fluids must be refrigerated and protected from light, and warmed to room temperature prior to administration.

Fluid preparations are delivered by infusion pumps and filters are used to remove particulate matter.

Higher dextrose levels in the parenteral fluid increases the need for potassium, magnesium, and phosphorus.

Use of PN unlikely to be beneficial in patients able to take enteral nutrition within 4-5 days after onset of the illness or who have suffered from a relatively minor injury.

Considerations prior to staring PN include: assessing nutritional status, determination of energy needs, evaluation of gastrointestinal function and estimating time that PN will be needed.


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