Nasogastric tube in critical care setting: combining ETCO2 and pH measuring to confirm correct placement

Abstract

AbstractIntroductionnasogastric tube (NGT) placement is a common procedure performed in critical care setting. Chest X-Ray is the diagnostic gold-standard to confirm correct placement, with the downsides of both the need for critical care patients’ mobilization and intrinsic actinic risk. Other potential methods to confirm NGT placement have shown lower accuracy compared to chest X-ray; ETCO2 and pH analysis have singularly yet investigated as an alternative to the gold standard. Aim of this study was to determine thresholds in combine measurements of ETCO2 and pH values, at which correct NGT positioning can be confirmed with the highest accuracy.Material & Methodsa prospective, multicenter, observational trial; a continuous cohort of eligible patients was allocated to two arms, to identify clear cut-off threshold able to detect correct NGT tip positioning with the maximal accuracy. Patients underwent general anesthesia and orotracheal intubation; in the first group difference between tracheal and esophageal ETCO2 values were assessed. In the second group difference between esophageal and gastric pH values were determined.Resultsfrom November 2020 to March 2021, 85 consecutive patients were enrolled: 40 in the ETCO2 group and 45 in the pH group. The ETCO2 ROC analysis for predicting NGT tracheal misplacement demonstrate an optimal ETCO2 cutoff value of 25.5 mmHg, where both sensitivity than specificity reach 1.0 (AUC 1.0, p < 0.001). The pH ROC analysis for predicting NGT correct gastric placement demonstrated the optimal pH cutoff value at 4.25, with a mild diagnostic accuracy (AUC 0.79, p < 0.001).DiscussionA device capable of combining the presence of a negative marker with a positive marker could be accurate enough in identifying the correct NGTs positioning. Further studies are required to validate the reproducibility of these results by a specific device, whose accuracy also ought to be compared with standard chest X-ray.Trial number: NCT03934515 (www.clinicaltrials.gov)