Using color flow detection of air insufflation to improve accuracy in verifying nasogastric tube position

Abstract

ObjectivesPrevious studies have shown that ultrasonography (USG), as an alternative to radiography, has a good accuracy in confirming nasogastric tube (NGT) position. Color flow detection of air insufflation is a novel approach in verifying NGT position. In our study, we aimed at evaluating its sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy in confirming the NGT position, as compared with 2-dimensional (2D) USG. MethodsThe study was conducted on adult patients over a period of 38months in an emergency department in Hong Kong. 2D USG and color flow Doppler imaging were conducted for each subject. Chest X-ray was used as the gold standard for NGT position confirmation. Results100 patients (59 males and 41 females) were recruited totally. Their mean age was 82. The sensitivity, specificity, PPV and NPV of 2D USG were 11.1% (95% CI 4.6%–17.6%), 100% (95% CI 100%–100%), 100% (95% CI 100%–100%), and 11.1% (95% CI 4.6%–17.6%) respectively. For color flow Doppler USG, the sensitivity, specificity, PPV and NPV were 90% (95% CI 83.7%–96.2%), 80% (95% CI 55.2%–100%), 97.6% (95% CI 94.3%–100%), and 47.1% (95% CI 23.3%–70.8%) respectively. The overall accuracy of color Doppler imaging was 89%, which was higher than that of 2D USG (20% only). ConclusionsColor flow detection of air insufflation improves the diagnostic accuracy of ultrasound in verifying NGT position. It is a quick investigation such that fasting time of patients and their length of ED stay can be shortened.