Parenteral nutrition (PN) is feeding a person intravenously, bypassing the usual process of eating and digestion. The person receives nutritional formulas that contain nutrients such as salts, glucose, amino acids, lipids and added vitamins.Total Parenteral nutrition (TPN) is provided when the gastrointestinal tract is nonfunctional because of an interruption in its continuity or because its absorptive capacity is impaired.TPN may be the only feasible option for nutrition 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, short gut syndrome, high-output fistula, certain pediatric GI disorders, e.g., congenital GI anomalies, prolonged diarrhoea regardless of its cause, or short bowel syndrome due to surgery.
TPN is an artifical method of feeding, fully passing the GI tract. As advanced is science is, this unnatural way of feeding the body is far from perfect and comes with several significant complications.Complications are either related to catheter insertion, or metabolic, including refeeding syndrome.
Catheter complications include pneumothorax, accidental arterial puncture, and catheter-related sepsis. The complication rate at the time of insertion should be less than 5%. Catheter-related infections may be minimised by appropriate choice of catheter and insertion technique.Metabolic complications include the refeeding syndrome characterised by hypokalemia, hypophosphatemia and hypomagnesemia.
Fatty liver is usually a more long term complication of TPN, though over a long enough course it is fairly common. The pathogenesis is still unknown.