Impact of pH 4.5 cut-off in nasogastric feeding tube confirmation on related X-ray use: single-centre study

Nasogastric (NG) feeding tubes play a vital role in delivering nutrition, hydration and medication to patients who are unable to meet their needs orally. They offer important advantages, one of which is that they can be inserted at the bedside by trained and competent staff, but there are recognised risks including inadvertent placement or displacement into the lungs. National Patient Safety Agency guidance stipulated pH testing to confirm NG tube position and recommended a pH cut-off of 5.5 or below to indicate that the tube is unlikely to be in the lungs and therefore ‘safe’ to use. There is concern that pH 5.5 is too high and suggestion that a lower pH threshold should be adopted. However, to date this proposal has been widely rejected on the basis that a lower threshold would lead to increased use of X-ray confirmation. This study describes the impact of a patient safety initiative adopting pH 4.5 or below on the use of chest X-ray at NG tube insertion. Snapshot audit data are detailed from 2018 to 2026. Results show that the use of X-rays did not increase with the lowering of the pH threshold. The study demonstrates that using pH 4.5 to improve patient safety is a simple and effective measure, using equipment and techniques that are familiar to nursing staff.