Parenteral nutrition: what it is, what it is for and how to administer it

Parenteral, or parenteral (PN) nutrition, is a method of administering nutrients that is done directly into the vein, when it is not possible to obtain nutrients through normal food. Thus, this type of nutrition is used when the person no longer has a functioning gastrointestinal tract, which most often happens in people in a very critical condition, such as stomach or intestinal cancer in a very advanced stage, for example.

There are two main types of parenteral nutrition:

Partial parenteral nutrition: only a few types of nutrients and vitamins are administered through the vein; Total parenteral nutrition (TPN): all types of nutrients and vitamins are administered through the vein.

Generally, people who are doing this type of food are also admitted to the hospital, to maintain a continuous assessment of their health status, however, it is possible that, in some cases, parenteral nutrition is also done at home and, in these situations, the doctor or nurse must explain how to administer the food correctly.

When is indicated

Parenteral nutrition is used in order to prevent malnutrition, especially in people who, for some reason, do not have a functioning gastrointestinal tract or who need to give rest to the stomach or intestine.

For this reason, parenteral nutrition is also indicated when oral feeding, even with a tube, cannot be done in optimal conditions for more than 5 or 7 days.

The indication of this type of nutrition can also be done in the short term, when it is done for up to 1 month, or in the long term, depending on the situation of each person:

Short term (up to 1 month)	Long term (more than 1 month)
Removal of much of the small intestine	Short bowel syndrome
High output enterocutaneous fistula	Chronic intestinal pseudo occlusion
Proximal enterotomy	Serious Crohn's disease
Serious congenital malformations	Multiple surgery
Pancreatitis or severe inflammatory bowel disease	Atrophy of the intestinal mucosa with persistent malabsorption
Chronic ulcerative disease	Palliative stage of cancer
Bacterial overgrowth syndrome (SBID)	-
Necrotizing enterocolitis	-
Complication of Hirschsprung's disease	-
Congenital metabolic diseases	-
Extensive burns, severe trauma or complex surgery	-
Bone marrow transplantation, blood disease or cancer	-
Renal or hepatic failure affecting the intestine	-

How to manage parenteral nutrition

Most of the time, parenteral nutrition is performed by the nursing staff at the hospital, however, when it is necessary to do the administration at home, it is important to first evaluate the food bag, ensuring that it is within the expiration date, which the bag remains intact and maintains its normal characteristics.

Then, in the case of administration through a peripheral catheter, one must follow the step-by-step:

Wash your hands with soap and water; Stop any infusion of serum or medication that is being administered through the catheter; Disinfect the connection of the serum system, using a sterile alcohol pad; Remove the serum system that was in place; Slowly inject 20 mL of saline; Connect the parenteral nutrition system.

This entire procedure must be done using the material indicated by the doctor or nurse, as well as a calibrated delivery pump that ensures that the food is provided at the correct speed and for the time indicated by the doctor.

This step-by-step should also be taught and trained with the nurse at the hospital, to clear up any doubts and ensure that complications do not arise.

What to watch out for during administration

When administering parenteral nutrition, it is important to evaluate the catheter insertion site, assessing the presence of swelling, redness or pain. If any of these signs appear, it is advisable to stop parenteral feeding and go to the hospital.

Type of parenteral nutrition

The type of parenteral nutrition can be classified according to the route of administration:

Central parenteral nutrition: it is done through a central venous catheter, which is a small tube that is placed inside a large-caliber vein, such as the vena cava, and which allows the administration of nutrients for a period greater than 7 days; Peripheral parenteral nutrition (PPN): it is performed through a peripheral venous catheter, which is placed in a smaller vein of the body, usually in the arm or hand. This type is best indicated when nutrition is maintained for up to 7 or 10 days, or when it is not possible to place a central venous catheter.

The composition of the bags used in parenteral nutrition can vary according to each case, but it usually includes fats, glucose and amino acids, as well as water and various minerals and vitamins.

Possible complications

The complications that can arise with parenteral nutrition are very varied and, therefore, it is always important to follow all the guidelines made by the doctor and other health professionals.

The main types of complications can be grouped according to the duration of PN:

1. Short term

In the short term, the most frequent complications include those related to the placement of the central venous catheter, such as pneumothorax, hydrothorax, internal bleeding, damage to the nerves in the arm or damage to the blood vessel.

In addition, infection of the catheter wound, inflammation of the blood vessel, obstruction of the catheter, thrombosis or generalized infection by viruses, bacteria or fungi may also occur.

At the metabolic level, most complications include changes in blood sugar levels, metabolic acidosis or alkalosis, decreased essential fatty acids, changes in electrolytes (sodium, potassium, calcium) and increases in urea or creatinine.

2. Long term

When aprenteral nutrition is used for a long term, the main complications include changes in the liver and vesicle, such as fatty liver, cholecystitis and portal fibrosis. For this reason, it is common for the person to have increased liver enzymes in blood tests (transaminase, alkaline phosphatase, gamma-GT and total bilirubin).

In addition, fatty acid and carnitine deficiency, alteration of the intestinal flora and atrophy of the intestinal velocities and muscles may also occur.