300: TRANSTRACHEAL ULTRASOUND AS A TOOL FOR PREDICTING ENDOTRACHEAL TUBE MALPOSITION

Abstract

Introduction: Chest x-ray (CXR) is a frequently employed imaging modality for determining ETT position and depth in the trachea. Ultrasonography is increasing in popularity as a diagnostic tool in critical care due to its accessibility and safety. Several investigations have compared ultrasonography to capnography for confirmation of ETT placement in the trachea; however, few studies have compared ultrasonography to chest X-ray in evaluating appropriate ETT depth in the trachea. While the confirmation of ETT placement is essential, the prevalence of ETT malposition in the trachea is 10-15%. The aim of this study was to evaluate the use of ultrasonography as a screening tool for determining ETT malposition in the trachea. Methods: We conducted a prospective observational study at a single tertiary care academic center of intubated patients in the intensive care unit to compare transtracheal ultrasound to daily CXR to determine ETT malposition. Trained investigators performed daily transtracheal ultrasonography to ascertain the position of the proximal ETT cuff boundary relative to the tracheal rings. A position between the third and fifth tracheal rings was considered appropriate. ETT depth was also determined using CXR. On a CXR, an ETT of 5 cm +/- 2 cm above the carina was considered in appropriate position. The sensitivity and specificity of ultrasonography to determine ETT malposition in the trachea was calculated. Results: A total of 76 patients and 187 ventilator days were assessed between Spring 2021 and Spring 2022. The average patient age was 57.8 years +/- 17.0 years. Most patients were intubated for airway protection (46.1%) and hypoxic respiratory failure (40.8%). In our patient population, the prevalence of ETT malposition in the tracheal was 10.16%. The overall sensitivity of ultrasound for determining ETT malposition in the trachea was 10.53% (95% CE 6.13% - 14.92%). However, the overall specificity of ultrasound for determining ETT malposition in the trachea was 95.24% (95% CE 92.19% - 98.29%). Conclusions: This prospective observational study suggests that airway ultrasonography should not be used as a screening tool to evaluate ETT malposition in the trachea given the low sensitivity but if detected has a high specificity for malposition. Further prospective studies are required.