A pneumothorax is a condition in which air gets between your lungs and your chest wall. Normally, two thin layers of moist tissue (pleurae) separate the lung and chest wall. Any air that leaks into this space (pleural space) will cause the lung tissue to collapse in proportion to the amount of air that enters the pleural cavity. You may be at increased risk of this condition if you have underlying lung disease, such as asthma or cystic fibrosis.

Air can collect in the pleural space for many reasons, such as due to:

• An injury that damages the chest wall, such as a stab or gunshot wound
• A broken rib that punctures the lung
• A surgical procedure that involves the chest wall or lung
• Spontaneous pneumothorax, which is thought to be due to the rupture of an air-filled blister on the surface of the lung and occurs most often in tall, thin men

In many cases, the cause can't be determined. Signs and symptoms of a pneumothorax include:

• Sudden, sharp chest pain
• Shortness of breath
• Chest tightness

A doctor can confirm a diagnosis of pneumothorax by a chest X-ray. Occasionally, the air leak seals itself. Depending on the severity, a doctor can remove the air from the pleural space with a tube inserted between the ribs and attached to a suction device. Surgery may be needed when suction isn't effective or for recurrent pneumothorax.

A collapsed lung is a serious condition that can be life-threatening. A partially collapsed lung may slowly re-expand without treatment. But a severe collapse will probably never re-expand on its own and may require surgery if untreated.

If air continues to enter the pleural space, a tension pneumothorax occurs. The large amount of air may push the center of the chest (mediastinum) toward the other lung, compressing it. This is life-threatening and requires immediate insertion of a chest tube between the ribs to relieve the increased pressure.