parenteral nutrition
Meaning of parenteral nutrition: Nourishment arrives already broken down and ready for the bloodstream, which is why the intestine can be bypassed for months or years.
Definition of parenteral nutrition
Parenteral nutrition is feeding delivered straight into a vein, supplying protein, calories, fat, vitamins and minerals without asking the intestine to absorb anything. It is used when the digestive tract cannot be reached, cannot absorb, or has to be rested. Given as the only source of nourishment it can meet a person's full nutritional needs indefinitely.
Who receives it?
The common thread is an intestine that cannot do its job. That covers a bowel shortened by surgery, a blockage, severe inflammatory bowel disease, an abnormal connection leaking intestinal contents, vomiting or diarrhea that will not settle, and a gut whose lining has been stripped by intensive treatment such as high-dose chemotherapy or a bone marrow transplant. It is also used after major abdominal surgery when the intestine has to be left alone. Some people need it for a few days, others for the rest of their lives at home overnight.
How does it differ from tube feeding?
| Feature | Parenteral nutrition | Enteral nutrition |
|---|---|---|
| Route | Into a vein | Into the stomach or intestine through a tube |
| Working gut needed | No | Yes, at least in part |
| Main hazards | Line infection, vein clots, liver and metabolic problems | Tube displacement, aspiration into the lungs, diarrhea |
Where the gut works even partly, enteral nutrition is the route used, because nutrients absorbed normally are handled by the liver in the usual order and the intestinal lining is kept in use. A lining that receives nothing thins and its barrier weakens, which is why even a small trickle of tube feed is often continued alongside feeding by vein.
What are the risks of feeding by vein?
The catheter is the first of them. A tube whose tip sits in a large central vein offers bacteria a direct path to the bloodstream, and infection of the line is the most frequent serious complication. The same vein can clot around the catheter. The formula itself brings the rest: blood sugar swings high on the feed and low if it stops abruptly, and salts, particularly potassium, phosphate and magnesium, shift as the body switches from breaking tissue down to building it up. That shift is dangerous in someone who has eaten little for a long stretch, when feeding restarted too quickly can drive those salts down sharply. Long courses carry their own problems, including liver inflammation, gallstones from a gallbladder that never empties, and thinning bone. None of this is a reason the treatment is avoided; it is why the blood is checked repeatedly and the formula adjusted rather than fixed.
Also known as
Used in a sentence
Parenteral nutrition was started because the patient's digestive tract could not be used during the acute illness.
Good to know
Parenteral nutrition bypasses the digestive tract entirely, which distinguishes it from enteral, or tube, feeding, a method that still relies on at least part of the digestive system to absorb nutrients.
Word origin
Where “parenteral nutrition” comes from
Formed from Greek para-, meaning beside, and enteron, meaning intestine, describing a route of feeding that bypasses the digestive tract entirely.