A pneumothorax (collapsed lung) is a buildup of air in the space between the lung and the chest wall. This pressure keeps the lung from expanding fully when you inhale. This can cause shortness of breath and chest pain.

A pneumothorax can be caused by an injury to the chest, such as a broken rib or a puncture wound. It may also occur suddenly because of a lung illness, such as COPD or pneumonia. Or a lung may collapse after lung surgery or another medical procedure. Sometimes it happens for no known reason.

Treatment can depend on the cause and severity of the pneumothorax. Some people stay in the hospital. A pneumothorax may be treated with rest. Oxygen may be used. A needle or a chest tube may be placed in the chest cavity to relieve the pressure on the lung. Sometimes surgery is done.