The effectiveness of auscultatory, colorimetric capnometry and pH measurement methods to confirm placement of nasogastric tubes: A methodological study

To determine the effectiveness of auscultatory, colorimetric capnometry and pH measurement methods for confirmation of correct nasogastric tube placement in critically ill patients.

Incorrect nasogastric tube placement causes serious complications.

This was a methodological and comparative study.

The study sample consisted of 88 new insertions of nasogastric feeding tubes between April 2018-2019. Results from the 'auscultatory', 'pH' and 'colorimetric capnometry' methods were compared with the location of the nasogastric tube as determined through radiography. Descriptive statistics, Eta analysis and the Cohen kappa compliance test as well as sensitivity and specificity were conducted.

There was a weak agreement (26.3%) between the auscultation and radiological evaluation for confirming nasogastric tube placement. The pH measurement and colorimetric capnometry methods were not correlated with radiological evaluation. Stomach pH increased as patient age increased and use of the colorimetric capnometry method failed to confirm the oesophageal and duodenal location. The specificity of the auscultation was low, and both the specificity and sensitivity pH methods were low.

It was determined that auscultation, measuring pH and colorimetric capnometry were unreliable methods for confirming placement of nasogastric tubes. It is recommended to confirm initial placement of the nasogastric tube with radiography and to develop effective and reliable non-radiological measurement methods that can be performed at the bedside.