For more information, visit http://www.nhlbi.nih.gov/health/health-topics/topics/atl/

What Is Atelectasis?

Atelectasis (at-uh-LEK-tuh-sis) is a condition in which one or more areas of your lungs collapse or don't inflate properly. If only a small area or a few small areas of lung are affected, you may have no signs or symptoms.

If a large area or several large areas of lung are affected, they may not be able to deliver enough oxygen to your blood. This can cause symptoms and complications.

Overview

To understand atelectasis, it helps to understand how the lungs work. Your lungs are organs in your chest that allow your body to take in oxygen from the air. They also help remove carbon dioxide (a waste gas that can be toxic) from your body.

When you breathe, air passes through your nose and mouth into your windpipe. The air then travels to your lungs' air sacs. These sacs are called alveoli (al-VEE-uhl-eye).

Small blood vessels called capillaries (KAP-ih-lare-ees) run through the walls of the air sacs. When air reaches the air sacs, oxygen passes through the air sac walls into the blood in the capillaries. At the same time, carbon dioxide moves from the capillaries into the air sacs. This process is called gas exchange.

The air sacs must remain open and filled with air for gas exchange to work well. Surfactant (sur-FAK-tant), a liquid that coats the inside of the lungs, helps the air sacs stay open. Deep breathing and coughing also help keep the air sacs open. (Coughing helps clear mucus and other substances from your airways.)

In atelectasis, part of the lung collapses or doesn't inflate. The air sacs in that part of the lung no longer fill with air. As a result, they can't take part in gas exchange.

If only a small area or a few small areas of lung are affected, you may have no signs or symptoms. This is because the rest of the lung can bring in enough oxygen to make up for the collapsed part.

If atelectasis affects a large area or several large areas of lung, your body's organs and tissues might not get enough oxygen-rich blood.

Conditions and factors that keep the lungs from fully expanding and filling with air can cause atelectasis. For example, atelectasis is common after surgery.

The medicine used during some types of surgery to make you sleep can decrease or stop your normal effort to breathe and urge to cough. Sometimes, especially after chest or abdominal surgery, pain may keep you from taking deep breaths. As a result, part of your lungs may collapse or not inflate well.

Outlook

The outlook for atelectasis depends on its cause. In adults, atelectasis often is short term. The collapsed air sacs slowly refill with air once the cause of the atelectasis is resolved.

If atelectasis persists, it may prevent the lungs from properly clearing mucus. This can lead to infections, such as pneumonia.

Atelectasis usually isn't life threatening. However, if it affects a large area of the lungs—especially in a baby, small child, or someone who has another lung disease or illness—it can be fatal if not treated quickly.

Other Names for Atelectasis

Closed lung
Partial lung collapse

What Causes Atelectasis?

Atelectasis can occur if the lungs can't fully expand and fill with air. Atelectasis has many causes.

Conditions and Factors That Prevent Deep Breathing and Coughing

Conditions and factors that prevent deep breathing and coughing can cause atelectasis. For example, if you're taking shallow breaths or breathing with the help of a ventilator, your lungs don't fill with air in the normal way.

Normally, when you take a deep breath, the base (bottom) and the back of your lungs fill with air first. However, if you're taking shallow breaths or using a ventilator, air may not make it all the way to the air sacs at the bottom of your lungs. Thus, these air sacs won't inflate well.

Atelectasis is common after surgery. The medicine used during some types of surgery to make you sleep can decrease or stop your normal effort to breathe and urge to cough. Sometimes, especially after chest or abdominal surgery, pain may keep you from taking deep breaths. As a result, part of your lung may collapse or not inflate well.

Pressure from outside the lungs also can make it hard to take deep breaths. Many factors can cause pressure outside the lungs. Examples include a tumor, a tight body cast, a bone deformity, or pleural effusion (fluid buildup between the ribs and the lungs).

Lung conditions and other medical disorders that affect your ability to breathe deeply or cough also may lead to atelectasis. One example is respiratory distress syndrome (RDS).

RDS is a breathing disorder that affects some newborns. It's more common in premature infants because their lungs aren't able to make enough surfactant. Surfactant is a liquid that coats the inside of the lungs and helps keep the air sacs open. Without enough surfactant, part of the lungs may collapse.

Other lung conditions and medical disorders that can cause atelectasis include pneumonia, lung cancer, and neuromuscular diseases. Rarely, asthma, COPD (chronic obstructive pulmonary disease), and cystic fibrosis are associated with atelectasis.

Migrating atelectasis in newborns is rare and might be caused by neuromuscular diseases. "Migrating" means that the part of the lung that collapses will change depending on the position of the baby.

An Airway Blockage

An airway blockage also can cause atelectasis. A blockage might be due to a foreign object (such as an inhaled peanut), a mucus plug, lung cancer, or a poorly placed breathing tube from a ventilator.

When a blockage occurs, the air that's already in the air sacs is absorbed into the bloodstream. New air can't get past the blockage to refill the air sacs, so the affected area of lung deflates.

Who Is at Risk for Atelectasis?

You might be at risk for atelectasis if you can't take deep breaths or cough, or if you have an airway blockage.

Conditions that can increase your risk for atelectasis include:

Surgery in which you're given medicine to make you sleep. This medicine can decrease or stop your normal effort to breathe and urge to cough.
Any condition or factor that causes pain when you breathe. Examples include surgery on your chest or abdomen, trauma, broken ribs, or pleurisy (inflammation of the membrane that surrounds your lungs and lines your chest cavity).
Being on a ventilator (a machine that supports breathing).
A blockage in your airway due to a foreign object, a mucus plug, lung cancer, or a poorly placed breathing tube.
Lung conditions and other medical disorders that affect your ability to breathe deeply or cough. Examples include respiratory distress syndrome, pneumonia, lung cancer, and neuromuscular diseases. Rarely, asthma, COPD (chronic obstructive pulmonary disease), and cystic fibrosis are associated with atelectasis.

People who have one of the conditions above and who smoke or are obese are at greater risk for atelectasis than people who don't smoke or aren't obese.

Infants and toddlers (birth to 3 years old) who have risk factors for atelectasis seem to develop the condition more easily than adults.

What Are the Signs and Symptoms of Atelectasis?

Atelectasis likely won't cause signs or symptoms if it only affects a small area of lung.

If atelectasis affects a large area of lung, especially if it occurs suddenly, it may cause a low level of oxygen in your blood. As a result, you may feel short of breath. Your heart rate and breathing rate may increase, and your skin and lips may turn blue.

Other symptoms might be related to the underlying cause of the atelectasis (for example, chest pain due to surgery).

If your child has atelectasis, you may notice that he or she seems agitated, anxious, or scared.

How Is Atelectasis Diagnosed?

Your doctor will diagnose atelectasis based on your signs and symptoms and the results from tests and procedures. Atelectasis might be detected as a result of a chest x ray done for an underlying lung condition.

Atelectasis usually is diagnosed by a radiologist, pulmonologist (lung specialist), emergency medicine physician, or a primary care doctor (such as a pediatrician, internal medicine specialist, or family practitioner).

Diagnostic Tests and Procedures

The most common test used to diagnose atelectasis is a chest x ray. A chest x ray is a painless test that creates pictures of the structures inside your chest, such as your heart, lungs, and blood vessels.

Your doctor also may recommend a chest computed tomography (to-MOG-rah-fee) scan, or chest CT scan. This test creates precise pictures of the structures in your chest. A chest CT scan is a type of x ray. However, the pictures from a chest CT scan show more details than pictures from a standard chest x ray.

Atelectasis often resolves without treatment. If the condition is severe or lasts a long time and your doctor thinks it's caused by an airway blockage, he or she may use bronchoscopy (bron-KOS-ko-pee). This procedure is used to look inside your airway.

During the procedure, your doctor passes a thin, flexible tube called a bronchoscope through your nose (or sometimes your mouth), down your throat, and into your airway. If you have a breathing tube, the bronchoscope can be passed through the tube to your airway.

A light and small camera on the bronchoscope allow your doctor to see inside your airway. Your doctor also can remove blockages during the procedure.

How Is Atelectasis Treated?

The main goals of treating atelectasis are to treat the cause of the condition and to reexpand the collapsed lung tissue. Treatment may vary based on the underlying cause of the atelectasis.

Atelectasis Caused by Surgery

If atelectasis is caused by surgery, your doctor may recommend that you take the following steps to fully expand your lungs:

Perform deep breathing exercises. These exercises are very important after surgery. While in the hospital, you may use a device called an incentive spirometer. This device measures how much air you're breathing in and how fast you're breathing in. Using this device encourages you to breathe deeply and slowly.
Change your position. Sit up or walk around as soon as possible after surgery (with your doctor's permission).
Make an effort to cough. Coughing helps clear mucus and other substances from your airways.

Your doctor also may suggest using positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP). Both devices use mild air pressure to help keep the airways and air sacs open.

Atelectasis Caused by Pressure From Outside the Lungs

If pressure from outside the lungs is causing atelectasis, your doctor will treat the cause of the pressure. For example, if the cause is a tumor or fluid buildup, your doctor will remove the tumor or fluid. This will allow your lung to fully expand.

Atelectasis Caused by a Blockage

If a blockage is causing atelectasis, you'll receive treatment to remove the blockage or relieve it. If the blockage is from an inhaled object, such as a peanut, your doctor will remove it during bronchoscopy. (For more information, go to "How Is Atelectasis Diagnosed?")

If a mucus plug is blocking your airways, your doctor may use suction to remove it. Other treatments also can help clear excess mucus from the lungs, such as:

Chest clapping or percussion. This treatment involves pounding your chest and back over and over with your hands or a device to loosen the mucus from your lungs so you can cough it up.
Postural drainage. For this treatment, your bed may be tilted so that your head is lower than your chest. This allows mucus to drain more easily.
Medicines. Your doctor may prescribe medicines to help open your airways or loosen mucus.

Atelectasis Caused by a Lung Condition or Other Medical Disorder

If a lung condition or other medical disorder us causing atelectasis, your doctor will treat the underlying cause with medicines, procedures, or other therapies.

How Can Atelectasis Be Prevented?

Not smoking before surgery can lower your risk of atelectasis. If you smoke, ask your doctor how far in advance of your surgery you should quit smoking.

After surgery, your doctor may recommend that you take the following steps to fully expand your lungs:

Perform deep breathing exercises. These exercises are very important after surgery. While in the hospital, you may use a device called an incentive spirometer. This device measures how much air you're breathing in and how fast you're breathing in. Using this device encourages you to breathe deeply and slowly.
Change your position. Sit up or walk around as soon as possible after surgery (with your doctor's permission).
Make an effort to cough. Coughing helps clear mucus and other substances from your airways.

If deep breathing is painful, your doctor may prescribe medicines to control the pain. This can make it easier for you to take deep breaths and fully expand your lungs.

Your doctor also might suggest using positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP). Both devices use mild air pressure to help keep the airways and air sacs open.

Clinical Trials

The National Heart, Lung, and Blood Institute (NHLBI) is strongly committed to supporting research aimed at preventing and treating heart, lung, and blood diseases and conditions and sleep disorders.

NHLBI-supported research has led to many advances in medical knowledge and care. Often, these advances depend on the willingness of volunteers to take part in clinical trials.

Clinical trials test new ways to prevent, diagnose, or treat various diseases and conditions. For example, new treatments for a disease or condition (such as medicines, medical devices, surgeries, or procedures) are tested in volunteers who have the illness. Testing shows whether a treatment is safe and effective in humans before it is made available for widespread use.

By taking part in a clinical trial, you can gain access to new treatments before they're widely available. You also will have the support of a team of health care providers, who will likely monitor your health closely. Even if you don't directly benefit from the results of a clinical trial, the information gathered can help others and add to scientific knowledge.

If you volunteer for a clinical trial, the research will be explained to you in detail. You'll learn about treatments and tests you may receive, and the benefits and risks they may pose. You'll also be given a chance to ask questions about the research. This process is called informed consent.

If you agree to take part in the trial, you'll be asked to sign an informed consent form. This form is not a contract. You have the right to withdraw from a study at any time, for any reason. Also, you have the right to learn about new risks or findings that emerge during the trial.

For more information about clinical trials related to your disease or condition, talk with your doctor. You also can visit the following Web sites to learn more about clinical research and to search for clinical trials:

For more information about clinical trials for children, visit the NHLBI's Children and Clinical Studies Web page.

Links to Other Information About Atelectasis

NHLBI Resources

Bronchoscopy (Health Topics)
How the Lungs Work (Health Topics)

Non-NHLBI Resources

Atelectasis (MedlinePlus)

Clinical Trials

Children and Clinical Studies
Clinical Trials (Health Topics)
NHLBI Clinical Trials
NIH Clinical Research Trials and You (National Institutes of Health)
ResearchMatch (funded by the National Institutes of Health)