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Tube Feeding

by David R. Thomas, MD

Tube feeding (enteral tube nutrition) may be used to feed people whose digestive tract is functioning normally but who cannot eat enough to meet their nutritional needs. Such people include those with the following:

  • A poor appetite for a long time

  • Severe protein-energy undernutrition (a severe deficiency of protein and calories)

  • Coma or greatly reduced alertness

  • Liver failure

  • A head or neck injury or another disorder that makes them unable to eat by mouth

  • A serious illness (such as burns) that increases nutritional requirements

If people are seriously ill or undernourished, they may be fed through a tube before surgery.

Compared with intravenous feeding, tube feeding has the following advantages:

  • It better preserves the structure and function of the digestive tract.

  • Cost is lower.

  • It probably causes fewer complications, particularly infections.

Procedure

Where the tube is inserted usually depends on how long tube feeding is needed:

  • For less than 4 to 6 weeks: A thin plastic tube is passed through the nose and down the throat until it reaches the stomach (called a nasogastric tube) or the small intestine (called a nasoduodenal tube). If the nose is damaged, the tube may be inserted through the mouth.

  • For a longer time: The tube is inserted directly into the stomach or small intestine through a small incision in the abdomen.

Nasogastric and nasoduodenal tubes can usually be inserted while the person is awake. The tube is lubricated and inserted into the nose and down the throat. A tube can cause gagging when it enters the throat, so the person is asked to swallow or is given water through a straw to help with swallowing. Swallowing can decrease or prevent gagging and help the tube pass down the throat. Once the tube is down the throat and enters the esophagus, it can be easily slid into the stomach or small intestine. Doctors sometimes do tests, such as an x-ray of the abdomen, to make sure the tube is correctly placed.

When a tube is inserted directly into the stomach or small intestine, doctors commonly use a percutaneous endoscopic gastrostomy (PEG) tube. Before this procedure, people are given a sedative and sometimes a painkiller, usually intravenously. Also, a numbing spray may be sprayed on the back of their throat to suppress the urge to cough or gag. Then doctors insert an endoscope through the mouth and into the stomach or small intestine. The endoscope has a camera on its tip, enabling doctors to view the interior of the stomach and determine where to place the PEG tube. Doctors then make a small incision in the abdomen and insert the PEG tube. People must fast before the procedure, and eating and drinking are limited after the test is completed until the gag reflex returns.

If a PEG tube cannot be placed, a feeding tube may be surgically inserted directly into the stomach or small intestine. This procedure may be done using a viewing tube (laparoscope) and require only a tiny incision just below the navel. Or it may require a relatively large incision in the abdomen because doctors need to view the area through the incision so that they can place the tube in the correct place.

People with feeding tubes should be sitting upright or with the head of the bed elevated during feeding and for 1 to 2 hours afterward. This position reduces the risk that they will inhale the food, and it allows gravity to help move the food through the digestive tract. Typically, a relatively large amount of food (called a bolus) is given several times a day. However, if these feedings cause nausea, small amounts of food are given continuously.

Formulas

Several different formulas are available. Typically, a formula that provides a complete balanced diet is used. Some formulas are designed to treat a specific deficiency and may contain a single nutrient, such as proteins, fats, or carbohydrates.

Also, specialized formulas are available for people with specific needs. They include concentrated formulas with less fluid for people whose fluid intake is limited, fiber-enriched formulas for people who are constipated, and lactose-free formulas for people who are lactose-intolerant.

Complications

Complications are common and can be serious.

Possible Problems With Tube Feeding

Problem

Possible Effects

Comments

Tube-related

Presence of the tube

Discomfort

Damage to the nose, throat, or esophagus

Sinusitis

The tube, particularly if large, can irritate tissues, causing pain and sometimes bleeding. In such cases, the tube is usually removed, and feedings are continued with a different kind of feeding tube.

Sinuses can become blocked, making infections more likely.

Blockage of the tube

Inadequate nutrition

Thick formulas or pills can block the tube. Sometimes doctors can dissolve the blockage by adding certain enzymes or substances formulated to break foods down.

Incorrect placement of the tube

Damage to the affected area

Coughing and gagging

Pneumonia

Rarely, the tube goes down the airways rather than the esophagus. As a result, food can enter the lungs. When the tube is placed in the airways, people who are conscious and alert cough and gag.

Accidental expulsion of the tube

Inadequate nutrition

Tubes often come out accidentally. If the tube is still needed to provide nutrition, it must be replaced.

Incorrect replacement of the tube

Peritonitis

When a tube shifts out of place, it must be removed and placed again. If the tube was originally inserted into the stomach or intestine, reinserting the tube is more difficult, and the tube may be placed outside the digestive tract. Then food can enter the space around the abdominal organs (abdominal cavity). As a result, the membrane that lines that space may become infected—a serious infection called peritonitis.

Formula-related

Intolerance of the formula

Diarrhea, digestive upset, nausea, and vomiting

The formula causes intolerable digestive symptoms in up to 20% of people being fed through a tube and in 50% of those with a serious illness. These symptoms are more common when feedings are given in large amounts (called boluses) given several times a day.

Diarrhea

Frequent, loose stools

Many formulas used in tube feeding contain sorbitol, which can cause or worsen diarrhea. When diarrhea occurs, many of the nutrients pass through the digestive tract without being absorbed.

Imbalances in nutrients

Abnormal levels of electrolytes

Abnormally high levels of blood sugar (hyperglycemia)

Too much fluid in the body (volume overload)

Doctors regularly measure weight (to check for too much water) and blood levels of electrolytes, sugar, and other substances. They then adjust the formula as needed.

Other

Backward flow of the stomach's contents into the esophagus (reflux)

Excess secretions in the mouth and throat

Inhalation (aspiration) of the formula into the lungs, which causes coughing and choking and increases the risk of infection

If people have either of these problems, they may inhale the formula into the lungs even though the tube is placed correctly and the head of the bed is elevated.

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