Bubbletrubble
Contributor
FYI... Excerpt from Bove and Davis' Diving Medicine 4th Edition (p. 479; Ch. 24 - Pulmonary Disorders):
A traumatic pneumothorax can be due to either blunt or penetrating trauma. In the case of blunt trauma, rib fractures cause lacerations of the lung surface, although other mechanisms can produce pneumothorax. In penetrating trauma, the pneumothorax can be due to lung injury or to a direct leak from the chest wall.
Traumatic pneumothoraces caused by isolated injury to the chest wall should not pose any risk to a diver; however, most traumatic pneumothoraces are associated with underlying lung injury as well. If the injury was severe enough to lead to radiographic changes, it could have led to areas of air-trapping. As a result, many authorities think that such persons should be advised not to dive, although extensive diagnostic and hyperbaric chamber testing might define those at greatest risk.