Your airways are branching tubes that run throughout each of your lungs. When you breathe, air moves from the main airway in your throat, sometimes called your windpipe, to your lungs. The airways continue branching and get progressively smaller until they end in little sacs called alveoli.

Your alveoli help to exchange the oxygen in the air for carbon dioxide, a waste product from your tissues and organs. In order to do this, your alveoli must fill with air.

When some of your alveoli don’t fill with air, it’s called “atelectasis.”

Depending on the underlying cause, atelectasis can involve either small or large portions of your lung.

Atelectasis is different from a collapsed lung (also called pneumothorax). A collapsed lung happens when air gets stuck in the space between the outside of your lung and your inner chest wall. This causes your lung to shrink or, eventually, to collapse.

While the two conditions are different, pneumothorax can lead to atelectasis because your alveoli will deflate as your lung gets smaller.

Keep reading to learn more about atelectasis, including its obstructive and nonobstructive causes.

The symptoms of atelectasis range from nonexistent to very serious, depending on how much of your lung is affected and how fast it develops. If only a few alveoli are involved or it happens slowly, you might not have any symptoms.

When atelectasis involves a lot of alveoli or comes on quickly, it’s hard to get enough oxygen to your blood. Having low blood oxygen can lead to:

  • trouble breathing
  • sharp chest pain, especially when taking a deep breath or coughing
  • rapid breathing
  • increased heart rate
  • blue-colored skin, lips, fingernails, or toenails

Sometimes, pneumonia develops in the affected part of your lung. When this happens, you can have the typical symptoms of pneumonia, such as a productive cough, fever, and chest pain.

Many things can cause atelectasis. Depending on the cause, atelectasis is categorized as either obstructive or nonobstructive.

Causes of obstructive atelectasis

Obstructive atelectasis happens when a blockage develops in one of your airways. This prevents air from getting to your alveoli, so they collapse.

Things that can block your airway include:

  • inhalation of a foreign object, such as a small toy or small pieces of food, in an airway
  • mucus plug (buildup of mucus) in an airway
  • tumor growing within an airway
  • tumor in the lung tissue that presses on the airway

Causes of nonobstructive atelectasis

Nonobstructive atelectasis refers to any type of atelectasis that isn’t caused by some kind of blockage in your airways.

Common causes of nonobstructive atelectasis include:

Surgery

Atelectasis can happen during or after any surgical procedure. These procedures often involve using anesthesia and a breathing machine followed by pain medications and sedatives. Together, these can make your breathing shallow. They can also make you less likely to cough, even if you need to get something out of your lungs.

Sometimes, not breathing deeply or not coughing can cause some of your alveoli to collapse. If you have a procedure coming up, talk to your doctor about ways to reduce your risk of postsurgical atelectasis. A handheld device known as an incentive spirometer can be used in the hospital and at home to encourage deep breathing.

Pleural effusion

This is a buildup of fluid in the space between the outside lining of your lung and the lining of your inner chest wall. Usually, these two linings are in close contact, which helps to keep your lung expanded. A pleural effusion causes the linings to separate and lose contact with each other. This allows the elastic tissue in your lung to pull inward, driving air out of your alveoli.

Pneumothorax

This is very similar to pleural effusion but involves a buildup of air, rather than fluid, between the linings of your lung and chest. As with pleural effusion, this causes your lung tissue to pull inward, squeezing air out of your alveoli.

Lung scarring

Lung scarring is also called pulmonary fibrosis. It’s usually caused by long-term lung infections, such as tuberculosis. Long-term exposure to irritants, including cigarette smoke, can also cause it. This scarring is permanent and makes it harder for your alveoli to inflate.

Chest tumor

Any kind of mass or growth that’s near your lungs can put pressure on your lung. This can force some of the air out of your alveoli, causing them to deflate.

Surfactant deficiency

Alveoli contain a substance called surfactant that helps them stay open. When there is too little of it, the alveoli collapse. Surfactant deficiency tends to happen to infants who are born prematurely.

To diagnose atelectasis, your doctor starts by reviewing your medical history. They look for any previous lung conditions you’ve had or any recent surgeries.

Next, they try to get a better idea of how well your lungs are working. To do this, they might:

  • check your blood oxygen level with an oximeter, a small device that fits on the end of your finger
  • take blood from an artery, usually in your wrist, and check its oxygen, carbon dioxide levels, and blood chemistry with a blood gas test
  • order a chest X-ray
  • order a CT scan to check for infections or blockages, such as a tumor in your lung or airway
  • perform a bronchoscopy, which involves inserting a camera, located on the end of a thin, flexible tube, through your nose or mouth and into your lungs

Treating atelectasis depends on the underlying cause and how severe your symptoms are.

If you’re having trouble breathing or feel like you’re not getting enough air, seek immediate medical treatment.

You may need the assistance of a breathing machine until your lungs can recover and the cause is treated.

Nonsurgical treatment

Most cases of atelectasis don’t require surgery. Depending on the underlying cause, your doctor might suggest one or a combination of these treatments:

  • Chest physiotherapy. This involves moving your body into different positions and using tapping motions, vibrations, or wearing a vibrating vest to help loosen and drain mucus. It’s generally used for obstructive or postsurgical atelectasis. This treatment is commonly used in people with cystic fibrosis as well.
  • Bronchoscopy. Your doctor can insert a small tube through your nose or mouth into your lungs to remove a foreign object or clear a mucus plug. This can also be used to remove a tissue sample from a mass so that your doctor can figure out what is causing the problem.
  • Breathing exercises. Exercises or devices, such as an incentive spirometer, that force you to breathe in deeply and help to open up your alveoli. This is especially useful for postsurgical atelectasis.
  • Drainage. If your atelectasis is due to pneumothorax or pleural effusion, your doctor may need to drain air or fluid from your chest. To remove fluid, they’ll likely insert a needle through your back, between your ribs, and into the pocket of fluid. To remove air, they may need to insert a plastic tube, called a chest tube, to remove extra air or fluid. The chest tube may need to be left in for several days in more severe cases.

Surgical treatment

In very rare cases, you may need to have a small area or lobe of your lung removed. This is usually only done after trying all other options or in cases involving permanently scarred lungs.

Mild atelectasis is rarely life-threatening and usually goes away quickly once the cause is addressed.

Atelectasis that affects most of your lung or happens quickly is almost always caused by a life-threatening condition, such as blockage of a major airway or when a large amount or fluid or air is compressing one or both lungs.