The visceral pleura covers the outer surface of the lungs, and the parietal pleura lines the chest wall. The intrapleural space is normally filled with a small amount of fluid that serves as a lubricant for the lungs to prevent friction during the normal motion of breathing. This fluid is the only substance that should be in the intrapleural space. In some cases, air enters the intrapleural space, and a condition called pneumothorax results.
Pneumothorax is a serious condition that can be caused by any number of factors.
The symptoms of pneumothorax range from none at all to extreme chest pain and shortness of breath. A pneumothorax may occur as a result of trauma or it may occur spontaneously, without trauma. Also, microorganisms collected in a mass in the chest cavity could produce gas, causing a pneumothorax. There are many factors that may predispose a person to developing a pneumothorax. Although there are many causes and risk factors for pnuemothorax, it does not actually occur very often.