What is atelectasis?

The lungs are a pair of organs in your chest that take in air to deliver oxygen to your body. Atelectasis (pronounced at-uh-LEK-tuh-sis) is the term for a collapse of one or more areas in the lung.

When you breathe in, your lungs fill up with air. This air travels to air sacs in your lungs (alveoli), where the oxygen moves into your blood. The blood delivers the oxygen to organs and tissues throughout your body.

When air sacs become deflated because of atelectasis, they cannot inflate properly or take in enough air and oxygen. If enough of the lung is affected, your blood may not receive enough oxygen, which can cause health problems.

Atelectasis often develops after surgery. It is not typically life-threatening, but in some cases, it needs to be treated quickly.

What causes atelectasis?

Atelectasis has many causes. Any condition that makes it hard to take deep breaths or cough can lead to a collapse in the lung.

People may call atelectasis or other conditions a “collapsed lung.” Another condition that commonly causes a collapsed lung is pneumothorax. Pneumothorax is the presence of air between the lung and the chest wall, which can cause the lung to collapse.


  • Surgery: Surgery is the most common reason people develop atelectasis. Medicine to keep you asleep during surgery (anesthesia) can affect your ability to breathe normally or cough. Pain after surgery could make deep breaths painful. Continued shallow breathing because of the pain can lead to deflated air sacs.
  • Chest pressure: Pressure from outside the lungs can make deep breathing difficult. This type of pressure can come from a tumor or other growth, a deformed bone, or a tight brace or body cast. If the cause of the pressure is not clear, your doctor will do additional tests to identify its source.
  • Blocked airway: A blocked airway can also cause atelectasis. If air cannot get past the blockage, the affected part of the lung could collapse. Mucus or an inhaled object could cause a blockage.
  • Other lung conditions: Other medical conditions involving the lungs can also be associated with atelectasis. These disorders could include lung cancer, pneumonia, pleural effusions (fluid around the lungs) and respiratory distress syndrome (RDS).

What are the signs and symptoms of atelectasis?

If atelectasis affects only a small area of the lungs, you may not have any symptoms. But if it affects larger areas, the lungs cannot fill with enough air, and the oxygen level in your blood may go down. When this happens, uncomfortable symptoms can occur, including:

  • Trouble breathing (shortness of breath)
  • Increased heart rate
  • Coughing
  • Chest pain
  • Skin and lips turning blue

Other conditions including asthma and emphysema can also cause chest pain and trouble breathing. If you experience these symptoms, you should see your doctor for the correct diagnosis and treatment.

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