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Section 2 - Complications of enteral nutrition

Introduction

Enteral tube feeding is the preferred method of nutritional support when the GI tract is functional and the patient is unable or unwilling to consume an adequate oral diet. The enteral route is efficient and cost-effective, however it is not always as easy as it looks. Gastrointestinal, mechanical, and metabolic complications can occur. It is important to thoroughly assess patients prior to initiation of tube feeding and to closely monitor them while they are receiving tube feedings in order to identify potential problems.


Gastrointestinal complications

Nausa and vomiting

Approximately 20% of patients receiving enteral tube feedings experience nausea and vomiting. Vomiting increases the risk of aspiration. Causes are multifactorial but delayed gastric emptying is the most common problem.

If delayed gastric emptying is suspected, consider reducing narcotic medications, switching to a low-fat formula, administering the feeding solution at room temperature, reducing the rate of administration, and administering a promotility agent.

If the patient appears distended, check gastric residuals before the next bolus feeding, or every four hours for continuous feeding. If gastric residuals are low yet nausea persists, consider antiemetic medications.

Diarrhea

Diarrhea is common in tube fed patients, occuring in 2% to 63% of patients depending on how it is defined. If clinically significant diarrhea develops during enteral tube feeding, consider the following options:

  • Add fiber, e.g., psyllium
  • Consider an enteral formula with fiber
  • Change the formula
  • Use an antidiarrheal agent

Constipation

Constipation can result from inactivity, decreased bowel motility, decreased fluid intake, impaction, or lack of dietary fiber. Poor bowel motility and dehydration may lead to impaction and abdominal distension. A standard abdominal x-ray is often effective for diagnosis and will clearly differentiate constipation from bowel obstructions.

Constipation usually is improved through adequate hydration and use of fiber-containing formulas, stool softeners, or bowel stimulants.

Malabsorption/maldigestion

Malabsorption is defined as impaired absorption of one or more nutrients. Clinical manifestations include unexplained weight loss, steatorrhea, diarrhea, anemia, tetany, bone pain, bleeding, neuropath, glossitis, or edema.

Causes of malabsorption are many and include gluten sensitive enteropathy, Crohn's disease, diverticular disease, radiation enteritis, enteric fistuals, HIV, pancreatic insufficiency, and short bowel syndrome. Knowledge of the patient's history and selection of an appropriate enteral product should help reduce or prevent malabsorption. However, depending upon the extent of disease, parenteral nutrition may be necessary.


Mechanical complications

Aspiration

Pulmonary aspiration is an extremely serious complication of enteral feeding and can be life-threatening in malnourished patients.

I can't help but relate a personal tragedy. This was the final insult to my father during his slow decline from lung cancer. Days before he died, Dad was given a bolus feeding (which was not even ordered for him), it caused an aspiration pneumonia. My sister-in-law (an RN) found the murder weapon (a feeding syringe) on his beside table. Shortly thereafter he slipped into a coma and died. I will never forget this horrible act against my father by those whom we had entrusted with his care. - - Rick

The incidence of clinically significant aspiration pneumonia is 1% to 4%. Symptoms of aspiriation include dyspnea, tachypnea, wheezing, rales, tachycardia, agitation, and cyanosis. Aspiration of small amounts of formula may not cause immediate symtoms, but a fever later may suggest development of aspiration pneumonia.

Risk factors for aspiration include:

  • Decreased level of consciousness
  • Diminished gag reflex
  • Neurologic injury
  • Incompetent LES
  • GI reflux
  • Supine position
  • Use of large-bore feeding tubes
  • Large gastric residuals

Use of small-bowel feeding tubes, promotility agents, periodic assessment of gastric residuals, and keeping the head of the bed elevated may reduce the risk of aspiration.

Tube malposition

Complications may arise during the placement of a feeding tube or simply from the presence of one. Feeding tube placement can cause bleeding, tracheal or parenchymal perforation, and GI tract perforation. Placement of tubes by trained personnel and using appropriate post-placement montoring should minimize these complications.

Presence of the feeding tube itself may cause upper and lower airway complications, aggravation of esophageal varices, cellulitis, necrotizing fasciitis, fistulas, and wound infection. Use of a small-bore feeding tube and very attentive nursing care can minimize many of these problems.

Tube clogging

Tube clogging is more likely with intact protein products and viscous products. Most clogs can be prevented by routine flusing of the feeding tube, use of clean technique to minimize formula contamination, and extreme care when administering medications via the feeding tube.

The recommended first line method to unclog a tube is to instill warm water using slight manual pressure. If this fails, a pancrelipase and sodium bicarbonate solution may be instilled in order to "digest" the clog.


Metabolic complications

Metabolic complications of enteral nutrition are similar to those that occur during PN, although the incidence and severity may be less. Careful monitoring can minimize or prevent metabolic complications.

Problem Cause Treatment
Hyponatremia Overhydration Change formula
Restrict fluids
Hypernatremia Inadequate fluid intake Increase free water
Dehydration Diarrhea
Inadequate fluid intake
Evaluate causes of diarrhea
Increase free water
Hyperglycemia Too many calories
Lack of adequate insulin
Evaluate caloric intake
Adjust insulin
Hypokalemia Refeeding syndrome
Diarrhea
Replace K
Evaluate causes of diarrhea
Hyperkalemia Excess K intake
Renal insufficiency
Change formula


Refeeding syndrome

Refeeding of severely malnourished patients may result in "refeeding syndrome" in which there are acute decreases in circulating levels of potassium, magnesium, and phosphate. The sequelae of refeeding syndrome adversely affect nearly every organ system and include cardiac dysrhythmias, heart failure, acute respiratory failure, coma, paralysis, nephropathy, and liver dysfunction.

The primary cause of the metabolic response to refeeding is the shift from stored body fat to carbohydrate as the primary fuel source. Serum insulin levels rise, causing intracellular movement of electrolytes for use in metabolism.

The best advice when initiating nutritional support is to "start low and go slow". Recommendations to reduce the risk of refeeding syndrome include:

  • Recognize patients at risk
    • Anorexia nervosa
    • Classic kwashiorkor or marasmus
    • Chronic malnutrition
    • Chronic alcoholism
    • Prolonged fasting
    • Prolonged IV hydration
    • Significant stress and depletion
  • Correct electrolyte abnormalities before starting nutritional support
  • Administer volume and energy slowly
  • Monitor pulse, I/O, electrolytes closely
  • Provide appropriate vitamin supplementation
  • Avoid overfeeding


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Section 2 - Complications of enteral nutrition