Merck Manual

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Quick Facts


(Collapsed Lung)


The Manual's Editorial Staff

Last full review/revision Aug 2019
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Two layers of thin membrane cover your lungs. The two membranes normally touch each other. But sometimes the space between the membranes, called the pleural space, fills up with air or fluid.

Air in the pleural space is called pneumothorax. Fluid in the pleural space is called pleural effusion.

What is a pneumothorax?

"Pneumo-" means air, and -"thorax" is another word for chest.

So a pneumothorax is a build-up of air in the pleural space. This causes part or all of your lung to collapse.

  • A pneumothorax happens when a weak area of your lung tears or your lung is injured so that air escapes into the chest

  • You may have shortness of breath and chest pain

  • Doctors can see a pneumothorax on chest x-ray or ultrasound.

  • Doctors usually place a tube in your chest to drain the air

What causes a pneumothorax?

A pneumothorax is caused by a tear or injury to the membrane around your lung. This can happen from:

What are the symptoms of a pneumothorax?

Symptoms of a pneumothorax depend on how much air enters the pleural space and how much of your lung collapses. Symptoms may happen suddenly or slowly. You may have:

  • Shortness of breath

  • Chest pain

  • Sometimes, pain in your shoulder

  • If a large pneumothorax happens suddenly, sometimes shock and cardiac arrest

Usually, your body reabsorbs the air and the pneumothorax goes away over 2 to 4 weeks.

How can doctors tell if I have a pneumothorax?

To tell if you have a pneumothorax, doctors listen to your breathing with a stethoscope. They’ll also do a chest x-ray or ultrasound.

How do doctors treat a pneumothorax?

Treatment depends on how large your pneumothorax is.

If there's only a small pneumothorax, doctors may:

  • Wait to see if the air goes away on its own

For a larger pneumothorax, or if you're having trouble breathing, doctors will:

  • Give oxygen

  • Place a small plastic tube in your chest (chest tube) to remove the air

Usually the chest tube is connected to a vacuum device to pull the air out. You'll have the chest tube for a couple days until your lung heals.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
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