Total Parenteral Nutrition
Total Parenteral Nutrition
Total Parenteral Nutrition
Total parenteral nutrition (TPN) is a way of supplying all the nutritional needs of the body by bypassing the digestive system and dripping nutrient solution directly into a vein.
TPN is used when individuals cannot or should not get their nutrition through eating. TPN is used when the intestines are obstructed, when the small intestine is not absorbing nutrients properly, or a gastrointestinal fistula (abnormal connection) is present. It is also used when the bowels need to rest and not have any food passing through them. Bowel rest may be necessary in Crohn's disease, pancreatitis, ulcerative colitis, and with prolonged bouts of diarrhea in young children. TPN is also used for individuals with severe burns, multiple fractures, and in malnourished individuals to prepare them for major surgery, chemotherapy, or radiation treatment. Individuals with AIDS or widespread infection (sepsis ) may also benefit from TPN.
Individuals need to tell their doctor if they have any allergies, what medications they are taking, if they are diabetic, have had liver, kidney, heart, lung, or hormonal disorders, and if they are pregnant. All these factors can affect the type and amount of TPN required.
TPN is normally given through a large central vein. A catheter is inserted into the vein in the chest area under local anesthesia and sterile conditions. Often the placement is done in an operating room to decrease the chance of infection. Several different types catheters are used based on the reason TPN is needed and the expected length of treatment. Catheters are made of silicone. Once the catheter is in place, a chest x ray is done to make sure the placement is correct.
Normally TPN is administered in a hospital, but under certain conditions and with proper patient and caregiver education, it may also be used at home for long-term therapy. TPN solution is mixed daily under sterile conditions. Maintaining sterility is essential for preventing infection. For this reason, the outside tubing leading from the bag of solution to the catheter is changed daily, and special dressings covering the catheter are changed every other day.
The contents of the TPN solution are determined based on the age, weight, height, and the medical condition of the individual. All solutions contain sugar (dextrose) for energy and protein (amino acids). Fats (lipids) may also be added to the solution. Electrolytes such as potassium, sodium, calcium, magnesium, chloride, and phosphate are also included, as these are essential to the normal functioning of the body. Trace elements such as zinc, copper, manganese and chromium are also needed. Vitamins can be included in the TPN solution, and insulin, a hormone that helps the body use sugar, may need to be added. The TPN catheter is used only for nutrients; medications are not added to the solution. Adults need approximately 2 liters of TPN solution daily, although this amount varies with the age, size, and health of the individual. Special solutions have been developed for individuals with reduced liver and kidney function. The solution is infused slowly at first to prevent fluid imbalances, then the rate is gradually increased. The infusion process takes several hours.
Successful TPN requires frequent, often daily monitoring of the individual's weight, glucose (blood sugar) level, blood count, blood gasses, fluid balance, urine output, waste products in the blood (plasma urea) and electrolytes. Liver and kidney function tests may also be performed. The contents of the solution are individualized based on the results of these tests.
Preparation to insert the catheter involves creating a sterile environment. Other special preparations are not normally necessary.
During the time the catheter is in place, patients and caregivers must be alert to any signs of infection such as redness, swelling, fever, drainage, or pain.
TPN requires close monitoring. Two types of complications can develop. Infection, air in the lung cavity (pneumothorax ) and blood clot formation (thrombosis) all can develop as a result of inserting the catheter into a vein. Metabolic and fluid imbalances can occur if the contents of the nutritional fluid are not properly balanced and monitored. The most common metabolic imbalance is hypoglycemia, or low blood sugar, caused by abruptly discontinuing a solution high in sugar.
Catheter— A hollow tube that is inserted into veins or other passages in the body to insert or remove fluid.
Electrolyte— An ion such as potassium sodium, or chloride dissolved in fluid that helps to regulate metabolic activities of the cell.
Fistula— An abnormal passage that connects one organ to another or that connects the organ to the outside of the body.
Ideally TPN will provide all the nutrients in the correct quantity to allow the body to function normally.
Fluid and electrolyte imbalances may occur that can lead to major organ failure.
Al-Jurf, Adel S. and Karen Dillon "Indications for Total Parenteral Nutrition (TPN)." University of Iowa Virtual Hospital. March 2003 [cited 16 February 2005]. 〈http://www.vh.org/adult/provider/surgery/totalparenteralnutrition〉.
"Drug Information: Total Parenteral Nutrition." Medline Plus Medical Encyclopedia. 1 April 2003 [cited 16 February 2005]. 〈http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a601166.html〉.
"Nutritional Support: Total Parenteral Nutrition." The Merck Manual. Eds. Mark H. Beers and Robert Berkow. 1995–2005 [cited 27 February 2005]. 〈http://www.merck.com/mrkshared/mmanual/section1/chapter1/1c.jsp〉.