Parenteral nutrition (PN) is feeding a person intravenously, bypassing the usual process of eating and digestion.It is called total parenteral nutrition (TPN) when no food is given by other routes.
Parenteral nutrition is provided when the gastrointestinal tract is nonfunctional because of an interruption in its continuity or because its absorptive capacity is impaired.It has been used for comatose patients, although enteral feeding is usually preferable, and less prone to complications. Indications: TPN may be the only feasible option for patients who do not have a functioning GI tract or who have disorders requiring complete bowel rest, such as the following: Some stages of Crohn's disease or ulcerative colitis, bowel obstruction, certain pediatric GI disorders, e.g., congenital GI anomalies, prolonged diarrhea regardless of its cause, or short bowel syndrome due to surgery.
Complications are either related to catheter insertion, or metabolic, including refeeding syndrome. Catheter complications include pneumothorax, accidental arterial puncture, and catheter-related sepsis.Metabolic complications include the refeeding syndrome characterised by hypokalemia, hypophosphatemia and hypomagnesemia. Hyperglycemia is common at the start of therapy, but can be treated with insulin added to the TPN solution. Hypoglycaemia is likely to occur with abrupt cessation of TPN. Liver dysfunction can be limited to a reversible cholestatic jaundice and to fatty infiltration.Also total parenteral nutrition increases the risk of acute cholecystitis due to complete unusage of gastrointestinal tract, which may result in bile stasis in the gallbladder.