Expiratory vs inspiratory films affects interpretation of pneumothorax guidelines

Radiographs of 49 spontaneous pneumothoraces were studied, showing that in the expiratory films, pneumothoraces were on average 9% larger. When applying British Thoracic Society or American College of Chest Physicians guidelines, this difference would have led to a different management strategy.

What is the difference in size of spontaneous pneumothorax between inspiratory and expiratory x-rays?
Emerg Med J. 2009 Dec;26(12):861-3