What is Parenteral Nutrition (or TPN)?
As you all know – everyone needs food/nourishment to live! So… what happens when a person is unable to eat normally or tolerate a tube feeding or cannot get enough intake? That is were parenteral nutrition comes in. Parenteral nutrition refers to feeding through the vein, or intravenous nutrition. This is very different from enteral nutrition because it does not enter the digestion pathway. Parenteral nutrition (PN) bypasses the normal digestion process (ingested food is broken down in the stomach and the intestines, absorbed in the bowel, and carried by the blood throughout the body). PN in inserted directly into the blood stream via an IV catheter to the vein bypassing the digestive tract. This is a sterile formula that is mixed in the pharmacy that contains water, amino acids, glucose, *lipids, vitamins and minerals and requires very close monitoring. Note: it is very common for their to be a lipid (fat) shortage (or a different drug shortage) so at many facilities lipids are only give lipids on Monday, Wednesday, and Friday and in limited quantities. Since parenteral nutrition may be someone’s only source of intake it is important that all essential nutrients are provided if PN will be used for a long duration. In addition to macronutrients, PN may also include electrolytes (sodium, potassium, chloride, phosphate, calcium, and magnesium) and trace elements (since, copper, manganese, and chromium). There is currently a shortage on trace elements so they are typically not included unless the patients has been on PN for over 30 days.
Who May Need Parenteral Nutrition?
People of all ages may receive parenteral nutrition and the time may be relatively short or for as long as needed. Patients may require PN for conditions or diseases that impair food intake, nutrition digestion or absorption. Common examples include: short bowel syndrome, GI fistulas, bowel obstruction, critically ill patients, severe acute pancreatitis, ulcerative colitis, or severe Crohn’s Disease.
How is Parenteral Nutrition Supplied?
An IV catheter (needle) is placed a large vein in either the arm, chest or neck. Common names for these catheters include: PICC, triple lumen, double lumen, single lumen catheter, and ports. Parenteral nutrition can be supplied continuously over 24 hours or cyclically down to about 12 hours a day. An infusion pump will control the rate at which the solution is supplied. Total parenteral nutrition (TPN) will need to be administered through a central access vein such as the chest or the neck and can be supplied in higher concentration to meet the needs of a patient who is relying solely on TPN for nutrition. Peripheral parenteral nutrition (PPN) is administered in lower concentrations and can be given through a peripheral vein such as through the arm and is mostly used for patients who are also consuming food through another source. TPN lines will go through a major vein and end at the superior vena cava.
What are the Potential Complications of Parenteral Nutrition?
- Infection – can be a common complication because of the chronic IV access point. If the infection is severe enough septic shock and death could ultimately occur.
- Blood Clots – if a blood clot forms in the IV lines but breaks off and enters the lung then death can result from a pulmonary embolism. Patients on long term tube feeds typically receive a Heparin flush periodically to dissolve clots.
- Liver Damage and Liver Failure – may appear as jaundice
- Cholecystitis – inflammation of the gallbladder
- Osteoporosis – bone disease
- Refeeding Syndrome – characterized by hypokalemia, hypophosphatemia and hypomagnesemia (or low serum potassium, phosphate, and magnesium levels)
- Hyperglycemia – high glucose levels, can be controlled with insulin
How is Parenteral Nutrition Monitored?
Depending on the facility, TPN will usually be monitored by a nutrition support care team that may include a physician, dietitian, pharmacist, and nursing staff. It is crucial to the patient’s safety that labs be monitored frequently in addition to monitoring weight status. The following labs should be closely monitored so that the order can change as needed:
- CBC – Complete Blood Count
- Electrolytes (Sodium, Potassium, Calcium, Phosphorus, Magnesium, Chloride, Bicarbonate)
- BUN – Blood Urea Nitrogen
- Glucose Levels