Chest. 2021 Feb 2:S0012-3692(21)00215-4. doi: 10.1016/j.chest.2021.01.058. Online ahead of print.
BACKGROUND: chest X-Ray (CXR) is universally accepted as the method of choice to confirm correct positioning of nasogastric tube (NGT). Considering also that radiation exposure could increase with multiple insertion in a single patient, bedside abdominal ultrasound (BAU) may be a potentially useful alternative to CXR in the management of NGT.
RESEARCH QUESTION: what is the accuracy of the BAU in confirming the correct positioning of NGT ?
STUDY DESIGN AND METHODS: after specific course of 10-hours training, we studied in a prospective, multicenter cohort, the validity of BAU to confirm correct NGT placement. All patients were also evaluated with auscultation (whoosh test) and with CXR. Every involved operator was blind to each other. Inter-observer agreement and accuracy analysis were calculated.
RESULTS: we evaluated 606 consecutive inpatients with an indication for NGT insertion. Eighty patients were excluded for protocol violation or incomplete exams and 526 were analyzed. BAU was positive, negative and inconclusive in 415 (78.9%), 71 (13.5%) and 40 (7.6%) respectively. The agreement between BAU and CXR was excellent. Excluding inconclusive results, BAU had a sensitivity of 99.8% (99.3-100%), a specificity of 91.0% (88.5-93.6%), a positive predictive value of 98.3% (97.2-99.5%) and a negative predictive value of 98.6% (97.6-99.7%). The accuracy of BAU slightly changed according to the different assignments of the uncertain cases and was improved by the exclusion of patients with an altered level of consciousness.
INTERPRETATION: Our results suggest that BAU has a good positive predictive value and may confirm the correct placement of NGT when compared with CXR. However, considering its sub-optimal specificity, caution is necessary before implementing this technique in clinical practice.