Total parenteral nutrition (TPN) is a form of feeding in which all nutritional needs are met with a solution which is infused into the veins. This feeding technique is only used in very specific settings, and care providers usually try to make sure TPN is only used in the short term. However, patients can and have received this type of feeding for decades in cases where this is necessary.
The most common reason to use this method is because the gastrointestinal tract is nonfunctional. In the case of a premature infant, this may be because it's not fully formed yet. For adults, it can be the result of complications of disease or severe trauma. People such as cancer patients, burn victims, and AIDS patients sometimes require TPN.
The biggest risk with this feeding method is a bacterial infection caused by leaving a catheter in place to provide the nutrition. The catheter needs to be meticulously cared for, and it is critical that it be used only for TPN, with any other fluids and medications being delivered through a different catheter. Some people who require this form of nutrition in the long term can develop gallstone and liver problems, as well, and it is important to monitor for these.
If the gastrointestinal tract is at all functional, a doctor will recommend partial parental nutrition in preference to TPN. This is because it is important to keep the GI tract in use; it can atrophy if not utilized. With partial parenteral nutrition, patients take some food by mouth or through a stomach tube, and receive other nutrients through an intravenous line. Patients may also be weaned from total parenteral nutrition in this way, giving their bodies time to adjust rather than thrusting them back onto a diet in which all their nutrition is derived through the digestive tract.
In some cases, people who still require TPN may be sent home, because they are otherwise fully healthy and do not require hospitalization. The patient will be given directions in handling feedings and caring for the catheter, and will be given a supply of IV bags which are ready for use. The patient and his or her care providers will also learn about programming the infusion pump which is usually used to deliver total parenteral nutrition. People who require long term feeding do need to make sure they are monitored closely for complications, but may not have other restrictions on their lifestyles or activity levels.