Comparing Sensitivity and Specificity of Ultrasonography With Chest Radiography in Detecting Pneumothorax and Hemothorax in Chest Trauma Patients: A Cross-Sectional Diagnostic Study.

Abstract

Background Thoracic trauma accounts for 20-25% of all traumas and is the third most frequent cause of death, after abdominal injury and head trauma. In the Emergency Department (ED), shifting an unstable patient to the X-ray room for detecting pneumothorax and hemothorax is always risky and bedside X-ray causes radiation exposure not only to the particular patient but also to the surrounding patients in a congested and busy ED. This can be avoided by using bedside ultrasonography (USG) as the initial imaging modality in chest trauma patients. Objective To compare the sensitivity and specificity of ultrasonography and chest radiography in detecting pneumothorax and hemothorax in chest trauma patients. Methods This cross-sectional diagnostic study was conducted for a period of one year at Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India, a tertiary care centre.All consecutive patients (n=255) with a suspected history of chest trauma were included in the study. The patients were evaluated bedside using USG by point of care ultrasonography trained emergency medicine physician and subsequently underwent chest radiography for documentation of pneumothorax and hemothorax. Sensitivity and specificity were calculated for ultrasonography and chest X-ray (CXR) compared with the composite gold standard (chest radiography and computed tomography thorax). Results Of the 255 patients, 89% were males. The mean age of the patients was 43.46 (standard deviation 16.3). Road traffic accident (RTA) was the most common mode of injury (81%). The median (interquartile range) time interval between injury and arrival at the hospital was four hours (2.5-7). About 16.1% of the patients had subcutaneous emphysema. About 88.2% of the patients were hemodynamically stable and 78% of the patients had associated other system injuries. The sensitivity and specificity of USG in detecting pneumothorax were 85.7% and 95.3% respectively and that of CXR were 71.4% and 100% respectively. Our study found that the sensitivity and specificity of USG in detecting hemothorax were 79% and 97.9% respectively and that of CXR were 62.9% and 100% respectively. Even in the subset of patients in whom a computed tomography scan was done, the sensitivity of USG was higher than that of CXR in detecting pneumothorax and hemothorax. The specificity of USG in detecting pneumothorax was the same as that of CXR and the specificity of USG in detecting hemothorax was higher than that of CXR in that subset of patients. Conclusion The sensitivities of USG in detecting pneumothorax and hemothorax were higher than that of CXR. The specificities of USG in detecting pneumothorax and hemothorax were comparable to that of CXR. Hence bedside USG performed by emergency physician during resuscitation helps in rapid diagnosis and early management of chest trauma patients.