Pendular motion of the mediastinum

1. Five types of mediastinal respiratory shift have been observed in twenty-one patients. 2. In Types I and II the mediastinum is midline on expiration but is displaced to one side during inspiration. In Type II these findings are noted both on fluoroscopy and on x-ray; in Type I the shift is usually not seen on x-ray. 3. In Type III the mediastinum is displaced to one side on expiration and to the opposite side during inspiration. 4. In Type IV the mediastinum is midline on inspiration but is displaced toward the normal side on expiration. 5. In Type V the mediastinum is pulled into the diseased side during both phases of respiration as a result of complete endobronchial occlusion.