Preventing Aspiration During Tube Feeding

Posted by | March 24, 2012 | Articles

As you may now, placement of a nasogastric or percutaneous gastrostomy tube does not always prevent aspiration. In fact, many patients continue to aspirate when NG and PEG tubes are placed.  Aspiration can occur from bacteria in the patient’s oral cavity or from reflux of the tube feeding.  Chronically, critically ill patients on mechanical ventilation are at particularly high risk of aspirating gastric contents.  Those who aspirate are 4 times more likely to develop pneumonia.  There are some precautions that the multidisciplinary team and caregivers can take to reduce the likelihood of aspiration.

 

Good oral hygiene is important for patients being fed by a feeding tube.  It has been shown that institutionalized adults being tube-fed had a higher prevalence of oropharyngeal pathogenic bacteria than thos fed orally (Leibovitz A, et al., 2003) Oral bacteria levels were highest in those receiving nasogastric tube feedings compared to those fed orally and by PEG. This suggests to us that tube-fed patients (especially those receiving nasogastric feedings) are at higher risk for bacterial pneumonia if aspiration occurs than are those who receive oral feedings.

Tube placement.  Correct placement of the feeding tube is also critical to the prevention of aspiration. A tube inadvertently positioned in the trachea or lung causes “aspiration by proxy” if tube feeding is initiated or medications are administered. In addition, a tube whose ports are situated in the esophagus increases the risk of regurgitation and aspiration. An X-ray remains the gold standard for ruling out respiratory placement of blindly inserted tubes.  For adults, an abdominal X-ray is preferred over a chest ray to determine where the feeding tube ends in the gastrointestinal tract. The American Association of Critical-Care Nurses recommends radiographic confirmation of correct position for all blindly placed tubes before the initial use of the tubes for administration of feedings or medications in critically ill patients. Testing the pH of a feeding tube aspirate,observing the appearance of the aspirate, and using end-tidal carbon dioxide monitoringare not sufficiently accurate to ensure nonrespiratory placement of blindly inserted tubes in high-risk patients. Further, no studies have been reported confirming that the auscultatory method is accurate in differentiating between respiratory and gastrointestinal placement of feeding tubes. However, multiple anecdotal reportshave been published of instances in which the method has failed, often with tragic results.

Gastric Residual.  It is important to measure the gastric residual during feeding to make sure the patient is tolerating the feeds. A high gastric residual volume increases the risk of gastroesophageal reflux and subsequent aspiration of gastric contents into the trachea. In one study, investigators reported a high correlation coefficient (0.93) between gastric residual volume and gastroesophageal reflux in 19 critically ill patients.  The most frequently cited volume of concern is 200 mL or greater (Methany, N, 2006).

Tube site and feeding method may also play a role in preventing aspiration.  Compared with gastric tube feeding, duodenojejunal (small intestine) tube feeding may be associated with a lower incidence of aspiration. This is especially true if the patient has significantly slowed gastric motility. Also, the risk of aspiration continues after placement of a gastrostomy tube. The consensus statement of the North American Summit on Aspiration in the Critically Ill Patient recommends continuous feeding (rather than intermittent feeding) in patients at high risk for aspiration. In a comparison of pump-assisted and gravity-controlled drip feeding for patients with percutaneous endoscopic gastrostomy tubes, those receiving pump-assisted feedings had less vomiting, regurgitation, and aspiration. (Methany, N., 2006)

Elevation of the head of bed.  Unless contraindicated, the head of the bed for a patient receiving tube feedings should be elevated more than 30. There is evidence that a sustained supine position (with the head of the bed flat) increases the probability of aspiration.

Aspiration of tube feeding in patients who are critically ill is common and dangerous. Patients are at risk of developing bacterial pneumonia.  Preventative strategies should be in place at hospitals to reduce aspiration of tube feedings by elevating HOB, checking residuals, taking chest xrays for the initial placement of nasogastric tubes, and performing good oral hygiene.

 

References:

Leibovitz A, et al. Pathogenic colonization of oral flora in frail elderly patients fed by nasogastric tube or percutaneous enterogastric tube. J Gerontol A Biol Sci Med Sci 2003;58(1):52-5.

Methany, Norma A. Preventing Respiratory Complications of Tube-Feedings: Evidence Based Practice. American Journal of Critical Care 2006; 15; 360-369.


 

13542 total views, 2 today

Tags: , , , , , , , , , ,

Leave a Reply

Your email address will not be published.