Comparative Analysis of Lung Ultrasound, Computed Tomography, and X-ray in the Diagnosis of Common Pathologies among Critically Ill Mechanically Ventilated Patients-A Prospective Observational Study

Abstract

Background and aims: Chest X-ray (CXR) and computed tomography (CT) are established imaging modalities for patients in respiratory distress, and lung ultrasound (LUS) has emerged as an efficient point-of-care alternative. This study aimed to evaluate the diagnostic performance of LUS and CXR in critically ill patients, utilizing CT thorax as the reference standard. Patient and methods: A prospective observational study was conducted in a tertiary care intensive care unit (ICU) involving mechanically ventilated adult patients requiring CT thorax. Before the CT, patients underwent portable CXR and LUS. Diagnostic performance metrics were calculated using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and AUC-ROC for pneumothorax, pleural effusion, consolidation, collapse, and pulmonary edema for CXR and LUS compared to CT. Inter-rater agreement was assessed using Cohen's κ. Results: A total of 110 patients were included in this study. Overall, the performance of LUS was significantly superior to CXR for diagnosing various pathologies. Lung ultrasound exhibited 100% sensitivity and 97% specificity, outperforming CXR (66.7% sensitivity) for the detection of pneumothorax. For pleural effusion, LUS achieved 100% sensitivity and specificity, reflecting perfect concordance with CT, especially for moderate and severe pleural effusions, while CXR had an accuracy of only 68.18%. Lung consolidation and collapse were identified with 100% sensitivity and PPV by LUS. Furthermore, the accuracy of LUS in diagnosing pulmonary edema was 96.4%, with a specificity of 95.3% and an NPV of 100%. Conclusion: Across five pathologies that were evaluated in this study, LUS consistently outperformed CXR in diagnostic accuracy and concordance with CT thorax.