Parenteral Nutrition • How artificial feeding works

Parenteral nutrition is a type of artificial feeding used in seriously ill people. It ensures that those affected receive essential nutrients without passing through the gastrointestinal tract. But when do you have to be artificially fed?

If a sick person is no longer able to eat themselves, there is a risk of uncontrolled weight loss and deficiency symptoms. Then parenteral nutrition with nutrient solution becomes necessary. Even those who are already affected by malnutrition can benefit from artificial nutrition using a nutrient solution, which serves as a life-sustaining measure.

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Nutrient deficiency: Recognizing deficiency symptoms

Indications for parenteral nutrition

Patients are particularly often dependent on the artificial supply of nutrients after serious operations. Serious disorders of the gastrointestinal tract such as short bowel syndrome and unwanted weight loss as a result of cancer, AIDS or autoimmune diseases are also indications. Older people and the chronically ill are often also among the artificially fed.

Diseases and various disease stages can have a major impact on nutrient requirements, energy requirements and changes in metabolism. Therefore, nutritional therapy has an important place in the treatment of diseases. Parenteral nutrition therapy can also have a positive effect on the chances of recovery.

How parenteral nutrition works

With parenteral nutrition, nutrients are infused directly into the bloodstream. This means that both the mouth and throat and the gastrointestinal tract are bypassed. This is necessary, for example, when the stomach or intestines are not able to process the food, for example in the case of a tumor, short bowel syndrome or a narrowing of the intestine. If someone is only fed parenterally, the doctor must ensure that the daily requirement of nutrients is adjusted to the individual needs.

The following nutrient supply is possible with an infusion:

  • Proteins in the form of amino acids

  • carbohydrates (glucose)

  • Fett

  • electrolytes

  • Trace elements such as iron, zinc, copper, manganese, molybdenum, chromium, selenium, iodine and fluorine

  • Vitamins: Vitamin A, Vitamin C, Vitamin D, Vitamin E, Vitamin K, Vitamin B1 (Thiamine), Vitamin B2 (Riboflavin), Vitamin B6 (Pyridoxine), Niacin, Pantothenic Acid, Biotin, Folic Acid and Vitamin B12

There are finished medicinal products that are industrially manufactured and contain standardized amounts of ingredients. On the other hand, there are individually manufactured parenteral preparations, also known as modular solutions, with which the exact need can be administered. Individual ingredients can be omitted or added. The disadvantage of these nutrient solutions is that they are more expensive and prone to impurities (contamination) when mixed.

How are you artificially fed?

The nutritional solution is injected into the blood intravenously. Depending on the period of artificial nutrition and the concentration of the nutrient solution, different types of vein access can be chosen:

  • Feeding duration 5 to 7 days and low concentration: With an indwelling cannula, various veins that are close to the skin surface (peripheral veins) can serve as access. This is often only possible if those affected can eat a proportion of other foods.

  • Duration of feeding longer than 7 days with a high concentration: A central venous catheter ensures that large amounts of nutrients enter the bloodstream over the long term. The catheter must be placed and maintained under strict sterile conditions. It should be made of Teflon, polyethylene, polyurethane or silicone rubber and needs to be replaced after about seven days.

  • Must be artificially fed long-term so-called Hickman-Broviac catheters or a port can be used. A port catheter is surgically implanted under the skin or, rarely, in the abdomen to gain access to the blood system. It can consist of one or more chambers. A thin tube runs from the chambers to the vein. The solution can be injected into the chambers from the outside with a syringe used specifically for this purpose.

What is the difference between enteral and parenteral nutrition?

Basically, parenteral nutrition with an infusion bag is the last resort. If those affected can take food elsewhere, for example via enteral nutrition, this is preferred. Both forms of artificial nutrition often complement each other.

In contrast to parenteral nutrition, enteral nutrition uses the digestive tract. The nutrient combinations are administered below the oral cavity, for example by means of a stomach tube. In most cases, the probe, a flexible plastic tube, is passed through the nose to the stomach (transnasal). Rarely, the tube is moved through the abdominal wall with a PEG tube in an operation. For example, when the nose and throat area is too narrow or injured. If patients have severe swallowing difficulties, they can also consume high-calorie liquid food.

Compared to parenteral nutrition, enteral nutrition is cheaper and involves fewer risks, since the risk of contamination is lower. In addition, it is easy to administer and maintains the function of the gastric and intestinal mucosa. The goal of artificial feeding is always the way back to oral feeding. If a person on total parenteral nutrition is on the mend, both forms of nutrition can also be used. There are the following options:

  • exclusive parenteral nutrition
  • predominantly parenteral nutrition and minimal enteral nutrition
  • partly parenteral and partly enteral nutrition
  • complete enteral nutrition
  • enteral and minimal oral nutrition
  • partial enteral and oral nutrition

Outpatient artificial nutrition

Not only patients in the intensive care unit or during an inpatient stay in a hospital can be artificially fed. Since the 1970s, outpatient enteral or parenteral nutrition has also been available. Patients can therefore also use artificial nutrition at home or in care facilities. PEG tubes are used for enteral feeding, which must be cleaned and checked regularly. This reduces the risk of complications such as inflammation.

With home parenteral feeding, a catheter or implanted port system must be chosen that involves the fewest complications and is easy to use. This must also be checked regularly by trained nursing staff. Those affected, relatives and trained nursing staff must pay particular attention to hygiene when maintaining the access routes.

Legal situation in artificial nutrition

Legally, no one can be forced to undergo artificial nutrition. If someone is no longer capable of making decisions, an authorized person takes over this task. Artificial nutrition is often necessary in the elderly and in the dying process. Here it must be decided whether the artificial supply of nutrients is accompanied by an increase in the quality of life or whether the inevitable death is thereby artificially prolonged. If artificial nutrition occurs against the will of the patient, this counts as physical injury.

Agents, in most cases relatives, are emotionally affected and do not want loved ones to starve or die of thirst. However, if artificial nutrition is no longer necessary from a medical point of view, it should not be given. This situation can be difficult for everyone involved. An intensive discussion between relatives and the treating specialist can help to create clarity and to weigh up again whether artificial nutrition alleviates the suffering of the person concerned or possibly prolongs it.

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Source: Lifeline | Das Gesundheitsportal by

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