Methods to Confirm Feeding Tube Placement: Application of Research in Practice

Shari Huffman; Pam Pieper; Kimberly S. Jarczyk; Alice Bayne; Eileen O'Brien

Disclosures

Pediatr Nurs. 2004;30(1) 

In This Article

Relevant Literature

A survey of pertinent literature was needed to build a research base for recommendations. The literature was examined in three areas: misplacement of feeding tubes, methods to verify placement, and limitations and future directions.

Misplacement of Feeding Tubes

Feeding tubes are improperly positioned if the feeding ports are located in the respiratory tract or esophagus, past the pylorus for tubes intended for gastric feedings, or in the stomach for feedings intended to be given into the intestine. Although it is difficult to know the actual frequency of feeding tube placement errors, the literature is full of studies and case reports documenting complications associated with feeding through an improperly placed tube. Research demonstrated that 13% to 20% of nasogastric tubes were improperly placed or migrated out of position over time in adults (Benya, Langer, & Mobarhan, 1990; Metheny, Spies, & Eisenberg, 1986; Neumann, Meyer, Dutton, & Smith, 1995). Metheny and colleagues (1986) also found that small-bore nasointestinal tubes were out of position 27%- 50% of the time. Metheny, Wehrle, Wiersema, and Clark (1998) noted that researchers estimate accidental placement into the respiratory system occurs in as many as 5% of initial placements of feeding tubes.

Studies involving children provide even more cause for concern. In their study on feeding tube placement in neonates, Weibley, Adamson, Clinkscales, Curran, and Bramson (1987) found that 39%-55% percent of naso- or oro-gastric tubes were improperly placed. Other researchers have noted a tube placement error rate varying from 16% to as high as 43.5% in the pediatric population (Ellett & Beckstrand, 1999; Ellett, Maahs, & Forsee, 1998). In a prospective study evaluating factors that place a child at risk for improper placement or displacement of enteral tubes, Ellett and Beckstrand (1999) found that coma, inactivity, dysphagia, and the use of Argyle® tubes increased the risk of tube placement error.

Methods to Verify Placement

Metheny (1988) reviewed commonly used procedures to verify feeding tube position and concluded that there was no published research to support conventional methods of placement verification. These methods include auscultation of insufflated air; checking the appearance of the aspirate; observing the patient for signs of choking, coughing, dysphagia, and the ability to speak; and looking for bubbling from the end of the tube when held under water. Further analysis and research over the ensuing years has supported these claims (Rakel et al., 1994). In one study, residents using auscultation incorrectly predicted that 15/16 tubes were properly positioned in the stomach (Neumann et al., 1995). Differentiating between gastric, pulmonary, esophageal, and intestinal placement cannot be accomplished by auscultation alone (Metheny, 1988; Rakel et al., 1994).

Excluding radiographic confirmation, the most reliable indicator of gastric feeding tube placement in adults is an aspirate pH of 4 or less (Metheny, Aud, & Ignatavicius, 1998; Metheny, Reed, Wiersema, McSweeney, Wehrle, & Clark, 1993; Metheny & Titler, 2001; Metheny et al., 1998; Metheny, Williams, Wiersema, Wehrle, Eisenberg, & McSweeney,1989; Neumann et al., 1995). Although not studied extensively, this indicator seems to hold true for children as well. In a study conducted in critically ill children, Gharpure, Meert, Sarnaik, and Metheny (2000) found that the mean pH of pre-pyloric aspirate samples (4.1) was consistently lower than the mean pH of post-pyloric samples (6.8). Metheny, Eikov, Rountree, and Lengettie (1999) reported similar findings in neonates, although the sample of intestinal specimens was insufficient to make comparisons to gastric samples. In this preliminary study, despite concerns about intrinsically higher neonatal gastric pH, mean pH of gastric aspirate was 4.81, with 83% of the samples below 6. It is likely that use of different cutoff points and other techniques will be required for neonates, and additional research in this population is highly desirable.

Limitations and Future Directions

Although research has consistently shown that using pH of aspirate to predict feeding tube location is more accurate than other nonradiographic methods, in selected instances, it is less reliable. In theory, pH of aspirate may not accurately predict tube location when the patient is receiving acid-suppressing medications or continuous feedings. However, the findings of two pediatric studies indicated no significant difference in aspirate pH under these conditions (Gharpure et al., 2000; Metheny, Eikov et al., 1999).

The pH method also cannot be used to differentiate between respiratory and intestinal placement because both typically result in aspirate pH levels greater than 5. Metheny and associates (1993) reported that up to 15% of gastric samples from adults may have a pH greater than 6. Therefore, a pH greater than 5 cannot be used to reliably confirm or predict distal tip location (Metheny et al., 1993; Metheny, et al., 1999). Aspirate pH also is not predictive when a feeding tube is located in the esophagus because the presence of gastroesophageal reflux may lead to both alkaline and acidic readings.

A number of other methods hold promise for improving the accuracy of bedside assessment of feeding tube position. One study in a pediatric intensive care setting reported using insufflation and aspiration of air to confirm post-pyloric placement of intestinal feeding tubes. Harrison and colleagues (1997) found that inability to withdraw more than 2 cc of a 10 cc aliquot of air predicted correct position in the intestine in 74 out of 75 attempts. Researchers have also reported using various combinations of aspirate pH, appearance, bilirubin, trypsin, and/or pepsin concentration to predict distal tip position (Gharpure et. al, 2000; Metheny, Eikov, et al., 1999; Metheny, Smith, & Stewart, 2000; Metheny et al., 1997; Metheny, Stewart, et al., 1999). Though these newer methods may lead to improved bedside assessment in the future, only appearance and pH of aspirate are currently available to clinicians.

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as:

processing....