Nutrition through the bloodstream (parenteral nutrition, TPN)

Many patients are unable to eat on ICU. In some very sick patients, the bowel can not cope with any food at all. When this happens nutrition can be given through the bloodstream. It is called “parenteral” nutrition or “Total Parenteral Nutrition (TPN)”.

Usually the digestive system breaks food down. It is made into smaller molecules such as protein, carbohydrates (basic sugars), fats, vitamins and minerals. These molecules are added to fluid. The fluid is very concentrated. It needs to go through larger veins. This means a patient needs a “central line (CVC)” or a “peripherally inserted central catheter (PICC)” for TPN.

Some patients might need to have parenteral nutrition for many weeks. Sometimes patients will go home and still be on it. For example this might happen for a patient who has an ongoing leak from the bowel or other complication from bowel surgery.

A feeding tube is preferred if a patient can tolerate food in their bowel. This delivers liquid food to the stomach.

Related topics

External resources (Australia and New Zealand)

  • Auspen –
    A society focussed on nutrition. Supports and promotes high standards for parenteral and enteral nutrition for patients in hospital and at home.

This topic was reviewed by an intensive care medicine specialist in July 2022.

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