When some of the alveoli in your lungs don’t fill with air, it’s called atelectasis.

Your airways are branching tubes that run throughout both 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 air sacs called alveoli.

Your alveoli are where your body exchanges 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.

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

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.

If you are seeing signs and symptoms of atelectasis, they may include:

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 you take a deep breath or cough
  • rapid breathing
  • increased heart rate
  • blue-colored skin, including the 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:

  • coughing up phlegm
  • fever
  • chest pain

Many things can cause atelectasis. Depending on the cause, healthcare professionals categorize atelectasis 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, and as a result they collapse.

Things that can block your airway include:

  • inhalation of a foreign object, such as a small toy or small pieces of food
  • mucus plug (a buildup of mucus) in an airway
  • tumor growing in 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 is not caused by some kind of blockage in your airways.

Common causes of nonobstructive atelectasis include:


Atelectasis can happen during or after any surgical procedure. These procedures often require you to:

  • receive anesthesia
  • use a breathing machine
  • take pain medications and sedatives after the surgery
  • potentially stay in bed

Together, these factors 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, speak with a healthcare professional about ways to reduce your risk of atelectasis after surgery.

You may have access to a handheld device known as an incentive spirometer to use in the hospital or at home to encourage deep breathing.

Pleural effusion

Pleural effusion 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, with the lining of the chest wall helping hold the lungs open. This helps keep your lung expanded.

However, a pleural effusion causes the linings to separate and lose contact with each other. The elastic tissue in your lung pulls inward, driving air out of your alveoli.


People sometimes confuse atelectasis with pneumothorax, which is also called collapsed lung. However, they’re different conditions.

That said, pneumothorax can lead to atelectasis because your alveoli will deflate as your lung collapses.

Pneumothorax is very similar to pleural effusion but involves a buildup of air, rather than fluid, between the linings of your lung and chest.

Air gets stuck in the space between the outside of your lung and your inner chest wall. This causes your lung to shrink or collapse, 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 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

The walls of your alveoli are normally coated with 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.

Risk factors of atelectasis

Risk factors for atelectasis include:

  • being under or having recently been under anesthesia, usually for surgery
  • undergoing cardiopulmonary bypass surgery, with increased risk during and after
  • abdominal and thoracic surgery, with increased risk during and after
  • smoking
  • having obesity or being pregnant, which can cause the diaphragm muscle to move out of its normal position and reduce lung capacity
  • having other conditions, including sleep apnea or lung conditions like asthma, cystic fibrosis, or chronic obstructive pulmonary disease (COPD)

To diagnose atelectasis, a healthcare professional 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 have you do one or more of the following tests:

  • Blood oxygen level test. A healthcare professional typically does this with an oximeter, a small device that fits on the end of your finger.
  • Blood test. A healthcare professional takes blood from an artery, usually in your wrist, and runs a blood gas test to check your blood chemistry and levels of oxygen and carbon dioxide.
  • Chest X-ray. A chest X-ray uses a small dose of radiation to create images of the inside of your chest so a healthcare professional can look for any abnormalities.
  • CT scan. A CT scan helps them check for infections or blockages, such as a tumor in the lung or airway.
  • Bronchoscopy. A bronchoscopy is a procedure that involves inserting a thin, flexible tube with a camera 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, a healthcare professional might suggest one or more of these treatments:

  • Chest physiotherapy. This involves moving your body in 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 also commonly used in people with cystic fibrosis.
  • Bronchoscopy. A healthcare professional can insert a small tube through your nose or mouth into your lungs to remove a foreign object or clear a mucus plug. They can also use the technique to remove a tissue sample from a mass to help figure out what’s causing the problem.
  • Breathing exercises. Exercises or devices, such as an incentive spirometer, can force you to breathe in deeply and help open up your alveoli. This is especially useful for postsurgical atelectasis.
  • Drainage. If your atelectasis is due to pneumothorax or pleural effusion, a healthcare professional may need to drain air or fluid from your chest. 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. This 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.

Healthcare professionals will usually only do this after trying all other options or in cases involving permanently scarred lungs.

It may be possible to prevent atelectasis in some cases.

To help prevent atelectasis during and after surgery, healthcare professionals may recommend that you:

  • stop smoking if you smoke, ideally 6 to 8 weeks ahead of surgery
  • do regular deep breathing exercises
  • use an incentive spirometer to encourage deep breathing
  • take medication
  • use a breathing device — a continuous positive airway pressure (CPAP) machine, for example

Children may be at a higher risk of inhaling small objects. You can help prevent them from developing obstructive atelectasis by keeping small objects safely out of reach.

People who have to stay in bed for long periods of time should try to move around regularly. It’s also important for them to frequently practice taking deep breaths.

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 suddenly is almost always caused by a life threatening condition, such as a blockage of a major airway or when a large amount of fluid or air is compressing one or both lungs.