Pneumothorax – expiration

Pneumothorax. When a pneumothorax is clinically suspected, we routinely perform CXR on both inspiration (as per usual) AND expiration. On an expiratory film, a pneumothorax will appear relatively larger, taking up a larger percentage of the thoracic cavity. The pleura is pushed further away from the chest wall, and the pneumothorax is usually a lot more obvious than on the inspiratory radiograph. In this example, the expiratory film shows an obvious pneumothorax, with a visible pleural line (arrow), and with shift of the mediastinum and trachea indicating tension. On the inspiratory film, the mediastinum and trachea are central, and the pleura is much closer to the chest wall. It would be quite easy to miss the pneumothorax if this was the only view provided.