Comparison of ultrasonography and CT in the determination of traumatic thoracic injuries

Claire Shaffer, MD PGY1

The Article: Kozaci N, et al, Comparison of ultrasonography and computed tomography in the determination of traumatic thoracic injuries, American Journal of Emergency Medicine (2018), https://doi.org/10.1016/j.ajem.2018.08.002

Background: Trauma is a major cause of mortality in the first 4 decades of life, thoracic injuries account for 10-50% of trauma deaths. The gold standard for evaluation for chest trauma is CT, however this modality is not available at bedside so may be dangerous for unstable patients and also requires significant radiation.  

Methods: Prospective study over approx. 3 years. Patients age >18 with multiple trauma including thoracic trauma found on PE were enrolled.  Physical exam was performed by the ED physician, then bedside TUSG (thoracic ultrasonography) was performed by a trained ED physician. Each area of the chest was divided into 6 areas that were evaluated in the transverse and longitudinal planes with both the linear and convex transducers. TUSG was performed by with patients in supine position:

  • Scanning for subcutaneous emphysema with linear probe marked by presence of E lines (meet the edge of the screen but do not emerge from pleural line

  • Scanning for fractures with linear probe (only the anterior chest was evaluated for fractures)

  • Scanning for PTX  with linear probe marked by lack of B lines, lung sliding, lung pulse (pleural line moves up and down with beat of heart), or “seashore”

  • Scanning for pulmonary contusion marked by B and C lines with linear probe, hepatizaiton with convex probe

  • Scanning for pericardial effusion or tamponade with convex probe

  • Scanning for hemothorax with convex probe

Patients were then taken to CT scan and evaluated for the same injuries

Results:

  • Subcutaneous Emphysema: 56% sensitive, 95% specific

  • Pneumothorax: 86% sensitive, 97% specific

  • Sternal Fracture: 83% sensitive, 97% specific

  • Clavicular Fracture: 85% sensitive, 100% specific

  • Rib Fracture: 67% sensitive, 98% specific

  • Hemothorax: 45% sensitive, 98% specific

  • Pulmonary contusion: 63% sensitive, 91% specific

Takeaway:

TUSG was found to be specific however not very sensitive for various type of thoracic trauma. Additionally, the sensitivity of TUSG was lower for almost every injury than other studies, which may have been due to the presence of multiple injuries or inability to properly position patients.  While TUSG may reveal the answer for instability in chest trauma, stable patients should still proceed to CT scan as TUSG is not sensitive enough to rule out traumatic thoracic injuries.