Dean.E.Baird.ctr@mail.mil

The purpose of this study is to identify the incidence of pulmonary hypertension in blast injury patients, as determined through main pulmonary arterial diameter on computed tomography (CT).

All polytrauma CT examinations from October 2010 through November 2012 were reviewed by one cardiothoracic radiologist and one experienced diagnostic radiologist. CT scans were performed with intravenous contrast and without cardiac gating. When possible, orthogonal dimension of the main pulmonary artery (PA) was measured on axial images at level of bifurcation, as was the diameter of the ascending aorta at the same level. Dilation of main PA was defined as a main PA diameter greater than 2.9 cm or a ratio of pulmonary artery to ascending aorta greater than one. Patients examined were military polytrauma victims, with the majority wounded by improvised explosive devices. Electronic health records were reviewed to capture all follow up imaging as available.

Of 565 patients with trauma CT scans, 338 included the chest. 114 out of a total of 338 polytrauma patients (34%) demonstrated dilation of the main pulmonary artery at level of bifurcation.

Although the differential diagnosis for main pulmonary artery dilation is broad, any dilation identified in previously healthy active duty soldiers implies abnormal pulmonary hemodynamics consistent with pulmonary hypertension. One-third of blast injury patients demonstrated pulmonary artery dilation, which is much higher than expected in a previously healthy patient population (.005%). Although a small percentage of these patients may have a congenital cardiac abnormality with left to right shunting and others may have pulmonary artery dilation secondary to aggressive resuscitation efforts, many of these patients may have developed pulmonary hypertension due to the underlying pathophysiology of blast injuries. Any interval change in main pulmonary artery size is not assessed in this study due to a lack of follow-up chest CT scans, but can be a subject of further investigation.

Pulmonary hypertension may be a previously unrecognized complication of blast injury, occurring in a significant percentage of blast injury patients, and may have therapeutic implications.