Neonatal Gastric Feeding Tubes, Part 2: Confirming Gastric Tube Placement

 

Last month, we reviewed the initial steps to ensure proper placement of a feeding tube or gavage tube in a neonate. Important steps to proper placement are measurement of the tube, and securing the tube to prevent accidental displacement. This month, we will review the recommendations around placement confirmation.

The position of the tube should be confirmed once it is placed and prior to each feeding. There are several practices used to confirm placement. Besides accurate measurement for placement, these include:

• Marking of the tube at point of entry
• Auscultation
• Aspiration of fluid
• pH testing
• Ultrasound
• Radiologic verification

In addition to making note of the cm marking at the lip line, two of the most common confirmations of neonatal gastric tube placement are infusing a small amount of air while listening over the stomach for the “whoosh” as air enters (presumably confirming tube placement in the stomach) and aspirating on the tube once placed to obtain gastric aspirate.

Various sources now recommend against use of the auscultation method. The audible sound of air entering the stomach cannot be distinguished from air entering the lung, should the tube be misplaced into the trachea. Additionally, the tip of the tube may be in the esophagus (not in far enough) or the tube could be coiled in the stomach and the air entry would still be audible.

The aspiration of gastric contents is not very reliable alone. The inability to obtain gastric contents when aspirating is not uncommon even when the tube is placed properly. Gastric contents are described as “clear, tan, off white or pale yellow”.1 When the tube is not in proper position, aspirate that may be obtained is described as “clear, tan, off white, pale yellow or green”.1 Obviously, color alone is not a reliable confirmation of proper placement.

Many units have started doing pH testing of the aspirate, provided it can be obtained.  Various sources place the pH level that confirms gastric placement as less than 4 to 5.2 A practical cut off for indication of gastric placement has been determined to be a pH < 5.1, 3  This demonstrates that, while helpful, testing of pH is not conclusive evidence that the tip of the gastric tube is in the stomach.

Use of ultrasound to determine gastric tube placement is being reported in adults, although not found to be sufficiently accurate alone.4  There are challenges that may be more or less problematic in neonates. Use of ultrasonography has been reported for endotracheal and percutaneous intravenous catheters.5 The logical next step is that these small bedside tools be used for gastric tube tip location. However, currently this is not common practice and presents some challenges.

The Child Health Patient Safety Organization6 acknowledges that x-ray is still the gold standard for determining placement of the gastric tube. They go on to state that other methods may be used instead of abdominal x-ray when this is not readily available.

The Children’s Hospital of Philadelphia1 developed an algorithm for confirming placement of gastric tubes. This algorithm allows the clinician to use centimeter marking at the lip, gastric aspirate appearance, and pH less than or equal to 5 as confirmation of proper placement. If there have been changes in the cm marking at the lip and changes in condition, an x-ray is obtained. If the pH is over 5 and secretions are obtained that are clear, tan, off white, pale yellow or green, they recommend an abdominal x-ray be obtained.

Requiring an x-ray with every tube change and/or every feeding may be excessive and unnecessary exposure to radiation with little added value. However, specific criteria for requiring x-ray confirmation of placement helps in ensuring proper placement while decreasing unnecessary exposure to radiation.

Let us know in the comments below: what procedures do you have in place to confirm placement of your NICU gastric feeding tubes?

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References:

1. Clifford, P., Heimall, L., Brittingham, L., & Finn Davis, K. (2015). Following the Evidence. The Journal of perinatal & neonatal nursing, 29(2), 149-161.
2. Irving, S. Y., Lyman, B., Northington, L., Bartlett, J. A., & Kemper, C. (2014). Nasogastric tube placement and verification in children: review of the current literature. Nutrition in Clinical Practice, 29(3), 267-276.
3. Gilbertson, H. R., Rogers, E. J., & Ukoumunne, O. C. (2011). Determination of a practical pH cutoff level for reliable confirmation of nasogastric tube placement. Journal of Parenteral and Enteral Nutrition, 35(4), 540-544.
4. Tsujimoto, Tsujimoto, Nakata, Akazawa, Kataoka. (2017). Ultrasonography for oncifmration of gastric tube placement. Cochrane Database of Systematic Reviews, Issue 4. CD012083.
5. Dennington, D., Vali, P., Finer, N. N., & Kim, J. H. (2012). Ultrasound confirmation of endotracheal tube position in neonates. Neonatology, 102(3), 185-189.
6. National Association of Childrens Hospitals (NACH), ECRI Institute. Blind Pediatric NG Tube Placements Continue to Cause Harm. Overland Park, KS: Child Health Patient Safety Organization, Inc; 2012.