A collapsed lung, or pneumothorax, is the collection of air in the space around the lungs. This buildup of air puts pressure on the lung, so it cannot expand as much as it normally does when you take a breath.

Air around the lung; Air outside the lung; Pneumothorax; Spontaneous pneumothorax

A collapsed lung occurs when air escapes from the lung and fills up the space outside of the lung, inside the chest. It may be caused by a gunshot or knife wound to the chest, rib fracture, or certain medical procedures.

In some cases, a collapsed lung occurs without any cause. This is called a spontaneous pneumothorax. A small area in the lung that is filled with air (bleb) can break open, sending air into the space around the lung.

Tall, thin people and smokers are more likely to have a collapsed lung.

The following lung diseases also increase your risk for a collapsed lung:

• Asthma
• COPD
• Cystic fibrosis
• Tuberculosis
• Whooping cough

Common symptoms of a collapsed lung include:

• Sharp chest pain, made worse by a deep breath or a cough
• Shortness of breath

A larger pneumothorax will cause more severe symptoms, including:

• Bluish color of the skin caused by lack of oxygen
• Chest tightness
• Easy fatigue
• Rapid heart rate 

Other symptoms that can occur with a collapsed lung include:

• Nasal flaring 

There are decreased or no breath sounds on the affected side when heard through a stethoscope. You may have low blood pressure.

Tests include:

• Arterial blood gases
• Chest x-ray 

A small pneumothorax may go away on its own. You may only need oxygen and rest.

The health care provider may use a needle to pull the extra air out from around the lung so it can expand more fully. You may be allowed to go home if you live near the hospital.

If you have a large pneumothorax, a chest tube will be placed between the ribs into the space around the lungs to help drain the air and allow the lung to re-expand.

The chest tube can be left in place for several days. You may need to stay in the hospital. However, you may be able to go home if a small chest tube is used.

Some patients with a collapsed lung need extra oxygen.

Lung surgery may be needed to treat your pneumothorax or to prevent future episodes. The area where the leak occurred may be repaired. Sometimes, a special chemical is placed into the area of the collapsed lung. This chemical causes a scar to form. This procedure is called pleurodesis.

If you have a collapsed lung, you are more likely to have another one in the future if you:

• Are tall and thin
• Continue to smoke
• Have had two collapsed lungs in the past

How well you do after having a collapsed lung depends on what caused it.

• Another collapsed lung in the future
• Shock

Call your health care provider if you have symptoms of a collapsed lung, especially if you have had one before.

There is no known way to prevent a collapsed lung, but you can decrease your risk by not smoking.

Light RW, Lee GY. Pneumothorax, chylothorax, hemothorax, and fibrothorax. In: Mason RJ, Murray JF, Broaddus VC, Nadel JA, eds. Textbook of Respiratory Medicine. 4th ed. Philadelphia, Pa: Saunders Elsevier; 2005:chap 69.

Maskell N; British Thoracic Society Pleural Disease Guideline Group. British Thoracic Society Pleural Disease Guidelines--2010 update. Thorax. 2010;65:667-669.