Laterality of air volume in the lungs long after blunt chest trauma

To clarify a cause of the persistent decrease in lung capacity seen several years after blunt chest trauma, 17 patients with blunt chest trauma (10 with unilateral lung contusion, 7 with bilateral lung contusions; 11 of these with unilateral flail chest) inflicted 1 to 6 years previously and 10 normal volunteers (control) were studied. Lung air volumes (AV) were measured by spirometry (AVsp) and by computed tomographic (CT) scan (AVCT = AVCT.Rt+AVCT.Lt) under the same conditions. Hemithoracic spaces were also calculated by CT scan. The average AVsp in patients (76% +/- 8%) was lower than in the controls (98% +/- 5%). AVCT was consistent with AVsp in all the measurements. %AVCT.Rt and %AVCT.Lt, which were adjusted by the ratio of AVCT.Rt to AVCT.Lt in the controls, decreased significantly in unilateral contused lungs (71% +/- 8%). Fifty-eight percent of contused lungs showed small fibrous changes on the CT scans. The ratio of the hemithoracic space on the flail chest side to the opposite side was 0.95 +/- 0.05. These results suggest that the persistent decrease in AV long after blunt chest trauma might be caused by a constriction of contused lung resulting from fibrous changes.