To reduce routine computed tomographic angiography for thoracic aortic injury assessment in level II blunt trauma patients using three mediastinal signs on the initial chest radiograph: a preliminary report

Abstract

Purpose: CTA is routinely ordered on level II blunt thoraco-abdominally injured patients for assessment of injury to the thoracic aorta. The vast majority of such assessments are negative. The question being asked is, Does the accurate interpretation of the three mediastinal signs permit reliable determination of which patients need CTA for aortic assessment? The purpose of this investigation was to evaluate the role of three specifically selected mediastinal anatomic signs on the initial supine chest radiograph (CXR) of adult level II blunt thoraco-abdominally injured patients for the presence or absence of a mediastinal hematoma. The presence of a mediastinal hematoma is typically used as an indicator for computed tomographic angiography (CTA). The three mediastinal signs are the right para-tracheal stripe (RPTS), left para-spinal line (LPSL), and the left apical extra-pleural area (LAPA).

Materials and methods: The patient triage designation (level II trauma) was made by the attending physician at the time of admission. The initial CXR image and the CTA report of the 197 adult blunt level II thoraco-abdominally injured patients obtained on the day of admission were compared. The CXR of each of the 197 patients was independently assessed by each of four observers specifically for the status of the three mediastinal signs. Each observer was blinded to the CTA report until after the status of the three mediastinal sign evaluation had been determined. Two or three of the mediastinal signs being positive were required to determine that the CXR was positive for a mediastinal hematoma.

Results: Two or three of the selected mediastinal signs were normal in 192 (97.5%) patients. None of these patients had either a mediastinal hematoma or a major aortic injury on CTA. In each of the remaining five (2.5%) patients, two or three of the mediastinal signs were abnormal. Each of these patients had a mediastinal hematoma and a major thoracic aortic injury on CTA.

Conclusions: This preliminary study suggests that the accurate interpretation of the three specifically selected mediastinal signs on the initial supine CXR of adult level II blunt thoraco-abdominally injured patients could reduce the need for routine CTA for thoracic aortic injury assessment, and requires verification by an additional study.

Keywords: Blunt thoraco-abdominal trauma; Left apical extra-pleural area (LAPA); Left para-spinal line (LPSL); Mediastinal hematoma; Right para-tracheal stripe (RPTS); Thoracic aortic injury.