Common complications of enteral feedings.

A guide to identifying and resolving problems seen with increasing frequency these days

The number of residents receiving enteral feedings has increased as more acutely ill residents are cared for in extended care facilities. The complications which may occur with enteral feedings can be life-threatening to the resident and frustrating to the nursing staff. Residents frequently have had the feeding tube inserted on an outpatient basis. The tolerance to enteral feedings which was previously established in the acute care setting is now shifted to the extended care setting.

An understanding of the complications and the necessary interventions can reduce the incidence of complications and enhance the care of these residents. This article will complement the article in the last issue of Nursing Homes ("Principles of Caring for Residents with Feeding Tubes," November/December, p. 37). by describing common complications, including gastrointestinal, respiratory, metabolic and mechanical problems.

Gastrointestinal Complications

Gastrointestinal complications are the most common complications experienced by residents receiving enteral feedings,|1~ and diarrhea is the most common gastrointestinal complication, occurring in up to 25% of those receiving enteral feedings.|2~ There are many factors which may contribute to diarrhea in residents, including:

Malnutrition

Commonly, the residents who require enteral feedings are malnourished with low serum albumin (protein) levels, which is why the enteral feedings are required. Malnutrition leads to changes in the gastrointestinal tract which affect the absorption of nutrients. Starvation leads to atrophy of the villi (absorptive structures) of the small intestine, decreasing the ability of these cells to absorb nutrients. Also, the mucosal cells of the small intestine frequently become edematous with malnutrition, thus reducing absorptive capacity.|3~ Utilizing the gut for enteral feeding promotes hyperplasia of the mucosal cells and the return of normal functioning.|4~ However, the return of normal functioning is a gradual process, and diarrhea will need to be controlled in the interim.

Medications

The use of medications is common in older adults. When combined with enteral feedings, determining if the medication or the feeding is causing the diarrhea becomes essential. Antibiotics may alter the normal flora and motility of the bowel and lead to diarrhea. Use of antibiotics may also lead to overgrowth of the Clostridium difficile toxin, which causes frequent loose stools and must be treated aggressively.|5~

Other medications which commonly cause diarrhea are antacids containing magnesium, cimetidine and other histamine blockers, and some antiarrhythmics (propanolol and digitalis). Oral medications and electrolyte elixirs may contain sorbitol or other hypertonic ingredients that can lead to diarrhea.|1~ Diarrhea Related to the Formula

Nurses frequently relate diarrhea to the tube feeding formula without investigating other etiologies. This complication can, of course, be related to the type of formula, but this occurs less commonly with the recent advances in the types of formulas available. If you do suspect the formula, determine its osmolality. (The osmolality describes the number of particles suspended in a solution). An isotonic tube feeding formula is usually better tolerated by residents. Isotonic formulas have an osmolality of approximately 300 mosm/kg water. Hypertonic formulas are not tolerated as well and more frequently lead to diarrhea. Hypertonic formulas have 400-1000 mosm/kg water.|5~ Formulas which contain lactose may also cause diarrhea, as many older adults have lactase insufficiency and cannot adequately digest lactose. Older adults who are malnourished have also been found to have a higher incidence of lactose intolerance because of the decreased production of lactase.|1~ If possible, question residents or their families about any history of milk intolerance, as milk has a high lactose content, and this may indicate a potential intolerance to specific formulas.

Bacterial contamination of formula is a significant cause of diarrhea. Contamination may occur during preparation, transfer to the feeding set-up, or if the set-up is hung too long. The use of commercially prepared formulas in ready-to-hang containers is recommended to reduce the risk of solution contamination.

Other gastrointestinal complications occur less commonly. They include: abdominal distention, cramping, slow gastric emptying, and constipation. Slow gastric emptying and abdominal distention are of major concern as they may lead to pulmonary aspiration. These problems may be caused by concomitant medical conditions (diabetes, or malnutrition), medications -- particularly narcotics, -- or the type of formula.|1~

Cramping may be caused by the changes in the gastrointestinal tract caused by malnutrition, lactose intolerance, or rapid administration of the formula. Constipation is most commonly seen in residents who have a history of this disorder or of laxative abuse.

Respiratory Complications

The most dangerous complication of enteral feeding is aspiration of formula, possibly causing a chemical pneumonitis.|6~ The residents reported to be at greatest risk for aspiration are: older adults with lowered level of consciousness, those receiving mechanical ventilation, those with delayed gastric emptying, and those with poor cough and gag reflexes.|7~

Clinical signs of aspiration include tachypnea, hypoxemia, respiratory acidosis, fever, and atelectasis or pneumonia present on chest x-ray.|8~ The presence of emesis or gastric contents in the pharynx or during suctioning may also lead to the diagnosis of aspiration. Residents with jejunostomy feedings are at less risk for aspiration as the feeding is being delivered distal to the pyloric and cardiac sphincters, which provide a protective mechanism against aspiration. Administering feedings continuously rather that intermittently and using small-bore feeding tubes may reduce the risk of aspiration. Other nursing interventions to prevent aspiration include elevating the head of the bed 30 to 45 degrees and checking gastric residuals every four hours, maintaining a residual level of less than 100 ml. Checking for placement of the feeding tube should be done every shift, especially for the intubated, unconscious, or frequently suctioned resident.|7~

Metabolic Complications

Hyperglycemia and fluid and electrolyte imbalances are commonly associated with parenteral feedings, but occur with enteral feedings as well. Patients who are diabetic, receiving steroids, hypermetabolic or receiving a high-calorie formula most commonly experience hyperglycemia. Older adults are at greater risk for developing hyperglycemia due to an aging-related glucose intolerance.|1~ Hyperglycemia can occur when feedings are administered too rapidly. The very sudden development of hyperglycemia in patients who were tolerating feedings well may be an indication of impending sepsis or infection|9~

Blood glucose levels should be checked at regular intervals for residents with diabetes mellitus. Other residents should be assessed for signs and symptoms of hyperglycemia, which include thirst, polyuria, and confusion. Feedings should be administered at a continuous rate rather than via bolus feedings to reduce the incidence of hyperglycemia.

Electrolyte abnormalities can be caused by fluid depletion or overload, or by over- or under-prescription of formula. Alterations in sodium and potassium levels occur most commonly. Residents develop hypernatremia as a result of dehydration or high sodium intake. Rehydration is the most common treatment for hypernatremia. Hyponatremia develops a result of overhydration and water losses from the gastrointestinal tract. Also, a gradual reduction in the serum sodium level may be noted due to the fact that most enteral feedings are equivalent to a 2 gram sodium diet.|1~

Metabolic acidosis in combination with renal insufficiency may lead to hyperkalemia. If hyperkalemia occurs, medications should be assessed, potassium intake reduced, and renal function evaluated. Diarrhea, diuretics, or large doses of insulin may cause hypokalemia.|10~ This problem can be corrected by changing the type of formula, administering potassium supplements, or replacing gastrointestinal losses.|10~

Mechanical Problems

Tube obstruction is one of the most common mechanical problems. Common causes of tube obstruction include medication fragments, formula residue adhering to the tube, and incompatibilities between the formula and medications. Slow formula administration promotes adherence of formula to the tube lumen and obstruction.|11~ Tubes irrigated with water and cola are less likely to clog than those irrigated with cranberry juice.|12~

The following measures will help reduce the incidence of tube obstruction: flush the tube with at least 30 ml of water every 4 hours during continuous feedings, prior to and following medication administration, and after intermittent feedings; use liquid medications; or use a controller pump to administer viscous feedings or when feedings are given at a slow rate.|12~ (Table 1).

TABLE 1
COMPLICATIONS AND ETIOLOGIES OF ENTERAL FEEDING PROBLEMS

COMPLICATION                       ETIOLOGY

Gastrointestinal

* Diarrhea                         Malnutrition
                                   Medications
                                   Hyperosmolar Formula
                                   Lactose intolerance
                                   Bacterial contamination

* Abdominal distention,            Medications
cramping                           Feeding too rapidly

* Delayed gastric emptying         Medications
                                   Diabetes

* Constipation                     Inadequate fluids
                                   Type of formula

Respiratory

* Aspiration                       Flat in bed
                                   Poor gastric emptying

Metabolic

* Hyperglycemia                    High calorie formula
                                   Rapid feeding

* Electrolyte imbalance            Over- or under-feeding
                                   Type of formula

Mechanical Problems

* Tube obstruction                 Medication fragments
                                   Formula viscosity
                                   Inadequate flushing

References

1. Kohn C, Keithley J. Enteral nutrition: Potential complications and patient monitoring. Nursing Clinics of North America 1989; 24(2):339-53.

2. Silk D. Fibre and enteral nutrition. Gut 1989; 30:246-64.

3. Schwartz D, Darrow K. Hypoalbuminemia-induced diarrhea in the enterally alimented patient. Nutrition in Clinical Practice 1988; 3:235-7.

4. Anderson B. Tube feeding: Is diarrhea inevitable? American Journal of Nursing 1986; 86(6):704-6.

5. Fitzgerald K. An overview of nutritional support strategies for patients undergoing major abdominal surgery. Progressions 1992; 4(4): 13-22.

6. Bastow M. Complications of enteral nutrition. Gut 1986: 27(Suppl 1):51-5.

7. Young C, White S. Preparing patients for tube feeding at home. American Journal of Nursing 1992: 92(4):46-53.

8. Cogen R, Weinryb J. Aspiration pneumonia in nursing home patients fed via gastrostomy tubes. American Journal of Gastroenterology 1989; 84:1509-14.

9. Rombeau J, Barot L. Enteral nutritional therapy. Surgery Clinics of North America 1981; 61(3):605-20.

10. Metheny N. 20 ways to prevent tube feeding complications. Nursing 1985: 1:47-50.

11. Irwin M, Openbrier D. Feeding ventilated patients safely. American Journal of Nursing 1985; 85:544-6.

12. Metheny N. Eisenberg P, McSweeney M. Effect of feeding tube properties and three irrigants on clogging rates. Nursing Research 1988: 37:165-9.

Barbara Blaylock, RNC, MSN, CETN, is Clinical Nurse Specialist in Enterostomal Therapy at St. Vincent Medical Center, Toledo, OH.