|
Enteral tube nutrition is indicated for patients who have a functioning GI tract and cannot ingest enough nutrients orally because they require intensive protein and caloric support or they are unable or unwilling to take oral feedings. Enteral nutrition, unlike parenteral nutrition, helps preserve the structure and function of the GI tract; it is also cheaper and probably causes fewer complications.
Specific indications include prolonged anorexia, severe protein-energy malnutrition, coma or depressed sensorium, liver failure, inability to take oral feedings due to head or neck trauma or neurologic disorders, and critical illnesses (eg, burns) causing metabolic stress. Other indications may include preparation of the bowel for surgery in seriously ill or undernourished patients, closure of enterocutaneous fistulas, and small-bowel adaptation after massive intestinal resection or in disorders that may cause malabsorption (eg, Crohn's disease).
Procedure:
If tube feeding is needed for ≤ 6 wk, a small-caliber, soft nasogastric or nasoenteric (eg, nasoduodenal) tube made of silicone or polyurethane is usually used. If a nasal injury or deformity makes nasal placement difficult, an orogastric or other oroenteric tube can be placed.
Tube feeding for > 6 wk usually requires a gastrostomy or jejunostomy tube. This tube is usually placed endoscopically, surgically, or radiologically. Choice depends on physician capabilities and patient preference. Jejunostomy tubes are useful for patients with contraindications to gastrostomy (eg, gastrectomy, bowel obstruction proximal to the jejunum). However, they do not pose less risk of tracheobronchial aspiration than gastrostomy tubes, as is often thought. Jejunostomy tubes are easily dislodged and are usually used only for inpatients.
Surgical placement of feeding tubes is particularly helpful if endoscopic and radiologic placement is unavailable, technically impossible, or unsafe (eg, because of overlying bowel). Open or laparoscopic techniques can be used.
Formulas:
Liquid formulas commonly used include feeding modules and polymeric or other specialized formulas.
Feeding modules are commercially available products that contain a single nutrient, such as proteins, fats, or carbohydrates. Feeding modules may be used individually to treat a specific deficiency or combined with other formulas to completely satisfy nutritional requirements.
Polymeric formulas (including blenderized food and milk-based or lactose-free commercial formulas) are commercially available and generally provide a complete, balanced diet. They can be used for oral or tube feedings. In hospitalized patients, lactose-free formulas are the most commonly used polymeric formulas. However, milk-based formulas tend to taste better than lactose-free formulas. Patients with lactose intolerance may be able to tolerate milk-based formulas given slowly by continuous infusion.
Hydrolyzed protein or sometimes amino acid formulas are used for patients who have difficulty digesting complex proteins. However, these formulas are expensive and usually unnecessary. Most patients with pancreatic insufficiency, if given enzymes, and most patients with malabsorption can digest complex proteins.
Other specialized formulas (eg, calorie and protein-dense formulas for patients whose fluids are restricted; fiber-enriched formulas for constipated patients) may be helpful.
Administration:
Patients should be sitting upright at 30 to 45 during tube feeding and for 2 h afterward. Tube feedings are given in boluses several times a day or by continuous infusion. Bolus feeding is indicated for patients who cannot sit upright continuously. Continuous infusion is necessary if boluses produce nausea; this method may reduce the incidence of diarrhea and aspiration.
For bolus feeding, total daily volume is divided into 4 to 6 separate feedings, which are injected through the tube with a syringe or infused by gravity from an elevated bag. After feedings, the tube is flushed with water to prevent clogging.
Because nasogastric or nasoduodenal tube feeding often causes diarrhea initially, feedings are usually started with small amounts of dilute preparations and increased as tolerated. Most formulas contain 0.5, 1, or 2 kcal/mL. Feeding often begins by giving a 0.5-kcal/mL solution (often obtained by a 50% dilution of a 1-kcal/mL commercially prepared solution) at 50 mL/h. An alternative is a 1-kcal/mL solution at 25 mL/h. Usually, these solutions do not supply enough water, particularly if vomiting, diarrhea, sweating, or fever has increased water loss. Extra water is supplied as boluses via the feeding tube or IV. After a few days, the rate or concentration can be increased to supply 1 kcal/mL at 50 mL/h or more as needed to meet caloric and water needs. Jejunostomy tube feeding requires even greater dilution and smaller volumes. Feeding usually begins at a concentration ≤ 0.5 kcal/mL and a rate of 25 mL/h. After a few days, concentrations and volumes can be increased to eventually meet caloric and water needs. Usually, the maximum that can be tolerated is 0.8 kcal/mL at 125 mL/h for 2400 kcal/day.
Complications:
Complications are common and can be serious. Tubes, particularly large tubes, can erode tissues, damaging the nose, pharynx, or esophagus. Sinusitis occasionally develops. Thick feedings or pills can block the lumen, particularly of small tubes. Sometimes blockages can be dissolved by instilling a solution of pancreatic enzymes or other commercial products.
Tubes can become dislodged, particularly jejunostomy tubes. Feeding tube replacement is more difficult and more likely to cause complications if the tube was placed invasively rather than noninvasively.
Nasogastric tubes can be misplaced intracranially if the cribriform plate is disrupted by severe facial trauma. Nasogastric or orogastric tubes can be misplaced into the tracheobronchial tree, causing coughing and gagging in responsive patients. Tracheobronchial misplacement may produce few symptoms in obtunded patients. If tracheobronchial misplacement is not recognized, feedings enter the lung, causing pneumonia. A dislodged gastrostomy or jejunostomy tube may be replaced into the peritoneal cavity; intraperitoneal feedings cause peritonitis.
In up to 20% of patients and 50% of critically ill patients, diarrhea and GI discomfort develop because the intestine cannot tolerate one of the formula's main nutrient components, particularly with bolus feeding. Sorbitol, often contained in liquid drug preparations given through feeding tubes, can exacerbate diarrhea. Nausea, vomiting, abdominal pain, and occasionally mesenteric ischemia may also develop.
Aspiration may occur, even though tubes are placed correctly, because of refluxed tube feedings or oropharyngeal secretions unrelated to feedings. Aspiration can usually be avoided by keeping the upper body elevated.
Electrolyte disturbances, hyperglycemia, volume overload, and hyperosmolarity can develop. Frequently monitoring weight and blood electrolytes, glucose, Mg, and phosphate (daily during the first week) is recommended.
Last full review/revision November 2005
Content last modified November 2005
| 
