What Is It?
A pneumothorax is commonly known as a collapsed lung. Normally, the outer surface of the lung sits next to the inner surface of the chest wall. The lung and the chest wall are covered by thin membranes called pleura.
A collapsed lung occurs when air escapes from the lungs or leaks through the chest wall and enters the space between the two membranes (pleural cavity). As air builds up, it causes the nearby lung to collapse.
A collapsed lung is most often caused by an injury to the lungs or chest wall, such as: