A novel method of verifying appropriate nasogastric tube placement: animal and human studies

It is important to verify the correct placement of nasogastric tube (NGT) but this can be unreliable, difficult to perform, or prone to confounding factors. We developed a novel method that uses ultrasound to verify the location of a specially designed NGT in real time. We describe our findings using this system in both animal and first-in-human studies.

Our system consists of a portable hand-held device coupled with a disposable nasogastric tube embedded with a sensor at its tip. During operation, the device is connected electrically to the external portion of the tube and then held over the abdominal wall whereby it will emit audible and visible signal when in-situ tube tip is proximate. For proof of concept, we used an anaesthetized Yorkshire-Landrace pig. Three blinded observers scanned for the location of the nasogastric tube thrice, with the location altered between each. In the first-in-man study, we placed the tube in 12 healthy volunteers, and five blinded and independent observers scanned for the location of the tip. An X-ray was taken of each of the volunteers.

In the animal study, the observers correctly identified the location of the nasogastric tube in every attempt. The mean time taken was 51.5 ± 7.53 seconds. In the human study, the nasogastric tube was detected 91.4% of the time when determined to be correctly placed in the stomach by the observers. The mean distance from the detected to actual NG tube tip was 6.5 cm (SD 6.9 cm). No complications occurred, except transient vomiting in one volunteer.

This novel nasogastric tube verification system is accurate and potentially offers advantages over existing methods.