Parenteral nutrition (feeding through a vein) and cancer

Parenteral nutrition (PN) means having nutrients and fluid directly into the bloodstream. It is a type of tube feeding for nutrition support.

It is usually used when a person cannot take nutrients in through their digestive system. For example, this may be because:

• they had surgery on the small bowel and the gut needs to rest
• the gut is not working
• there is a blockage in the bowel (bowel obstruction)
• it is difficult to insert the tubes used for enteral nutrition (EN). This may happen after some types of surgery to the head and neck or surgery to the stomach.

PN is sometimes called TPN, which means total parenteral nutrition. But it is not always possible to provide total nutrition through the bloodstream.

PN is usually given through a thin tube. A healthcare professional inserts it into a large vein in the neck or chest. The tube is called a central line. Sometimes you have it through a thin tube inserted into a vein in the arm that goes up into a larger vein in the chest. This is called a PICC line (peripherally inserted central catheter). 

Parenteral nutrition

Sometimes, a smaller vein in the arm is used, but this is less common. It may be used if you only need feeding for a short time, usually less than 10 days. It is also only possible if the amount of fluid you can have is not restricted. This is because PN needs to be more dilute if an arm vein is used. The doctors will decide the best type of feeding for you.

PN is usually started slowly. Your feed will be reduced over a few days when you no longer need it.

You usually have PN in hospital, but it may sometimes be possible to have it at home.

Rarely, an infection may develop either inside the line or where it comes out (the exit site). You should tell your doctor if:

• the skin around the exit site becomes red or darker, depending on your skin type
• the surrounding area becomes swollen or sore
• you notice fluid coming from the exit site
• you develop a high temperature (fever) or feel unwell.

You may be given antibiotics. If the infection is serious, the tube may need to be removed.

It is possible for a blood clot (thrombosis) to form at the tip of the central line. If this happens, the tube may have to be removed. You may be given some anti-clotting medicines to stop this from happening. These are usually added to the feed.

You will have regular blood tests while having PN. This is to check your levels of sugar, minerals and other substances. Your dietitian will plan the feed you have. Some people may need to have their feed specially prepared for them, taking into account any specific nutritional needs.