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Monday, September 30, 2019

Total Parenteral Nutrition TPN Nursing Management

Total Parenteral Nutrition

TPN refers to the delivery of all nutrients by the intravenous route. It is used when the GI tract is not functional or when nutritional needs cannot be met solely through the GI tract. Likely candidates for TPN include patients who have a severely impaired absorption (e.g., short bowel syndrome, collagen vascular diseases, radiation enteritis), intestinal obstruction, peritonitis, or prolonged ileus. Some postoperative, trauma, or burn 
patients may need TPN to supplement the nutrient intake that they are able to tolerate by the enteral route.

Types of Parenteral Nutrition. TPN involves administration of highly concentrated dextrose (25% to 70%), providing a rich source of calories. These highly concentrated dextrose solutions are hyperosmolar, as much as 1800 mOsm/L, and therefore must be delivered through a central vein. Peripheral parenteral nutrition (PPN) has a glucose concentration of 5% to 10% and may be delivered safely through a peripheral vein. PPN solution delivers nutrition support in a large volume that cannot be tolerated by patients who require fluid restriction. It provides short-term nutrition support for a few days to less than 2 weeks.

Regardless of the route of administration, PPN and TPN provide glucose, fat, protein, electrolytes, vitamins, and trace elements. Although dextrose–amino acid solutions are commonly thought of as good growth media for microorganisms, they actually suppress the growth of most organisms usually 
associated with catheter-related sepsis, except yeasts. However, because the many manipulations required to prepare solutions 
increase the possibility of contamination, TPN solutions are best used with caution. They should be prepared under laminar flow conditions in the pharmacy, with avoidance of 
additions on the nursing unit. Solution containers need to be inspected for cracks or leaks before hanging, and solutions 
must be discarded within 24 hours of hanging. An in-line 0.22-micron filter, which eliminates all microorganisms but not endotoxins, may be used in the administration of solutions. Use of the filter, however, cannot be substituted for 
good aseptic technique.

Nursing Management of Potential Complications. 

Nursing management of the patient receiving TPN includes catheter care, administration of solutions, prevention or correction of 
complications, and evaluation of patient responses to intravenous feedings. TPN requires an indwelling catheter in a central 
vein, it carries an increased risk for sepsis and potential insertion-related complications such as pneumothorax and hemothorax. Air embolism is also more likely with central vein 
TPN. Patients requiring multiple intravenous therapies and frequent blood sampling usually have multilumen central venous catheters, and TPN is often infused through these catheters.
Some clinical studies have reported that catheter-related sepsis is higher with multilumen catheters; others have found 
no difference compared with single-lumen catheters. Patients requiring multilumen catheters are likely to be very ill and 
immunocompromised, and scrupulous aseptic technique isessential in maintaining their multilumen catheters. The manipulation involved in frequent changes of intravenous fluid and obtaining blood specimens through these catheters increases the risk of catheter contamination. Peripherally inserted central catheters (PICC) allow central venous access 
through long catheters inserted in peripheral sites. This reduces the risk of complications associated with percutaneous cannulation of the subclavian vein and provides an alternative to PPN.

The indwelling central venous catheter provides an excellent nidus for infection. Catheter-related infections arise from 
endogenous skin flora, contamination of the catheter hub, seeding of the catheter by organisms carried in the bloodstream 
from another site, or contamination of the infusate. Good hand washing and scrupulous aseptic technique in all aspects of catheter care and TPN delivery are the primary steps for prevention of catheter-related infections. Other measures to reduce the incidence of catheter-related infections include using maximal 
barrier precautions (e.g., cap, mask, sterile gloves, sterile drape) at the time of insertion, tunneling the catheter underneath the skin, use of a 2% chlorhexidine preparation for skin cleansing, no routine replacement of the central venous catheter for prevention of infection, and use of antiseptic- or antibiotic-
impregnated central venous catheters.

  Metabolic complications associated with parenteral nutrition include glucose intolerance and electrolyte imbalance. Slow 
advancement of the rate of TPN (25 mL/hr) to goal rate allows pancreatic adjustment to the dextrose load. Capillary blood glucose should be monitored every 4 to 6 hours. Insulin can be added to the TPN solution or can be infused as a separate drip to control glucose levels. Rapid cessation of TPN may not lead to hypoglycemia; however, tapering the infusion over 2 to 4 hours is recommended.

Serum electrolytes are obtained on starting TPN. During critical illness, levels should be monitored and corrected daily and then weekly or twice weekly after the patient is more stable. The refeeding syndrome is a potentially lethal condition characterized by generalized fluid and electrolyte imbalance. It 
occurs as a potential complication after initiation of oral, enteral, or parenteral nutrition in malnourished patients. During chronic starvation, several compensatory metabolic changes occur. The reintroduction of carbohydrates and amino acids leads to increased insulin production. This creates an anabolic environment that increases intracellular demand for phosphorus, potassium, magnesium, vitamins, and minerals.These metabolic demands result in severe shifts from the extracellular compartment. Increased insulin levels also result in fluid retention. Severe hypophosphatemia, hypokalemia, and 
hypomagnesemia result in altered cardiac, gastrointestinal, and neurologic function. In particular, hypophosphatemia causes a 
decrease in diphosphosoglycerate and limits the many reactions that require ATP. Hypophosphatemia and other electrolyte deficiencies may lead to respiratory failure, congestive heart failure, and dysrhythmias.


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