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 properly.
Atelectasis is very common after surgery. The medicine used during surgery to temporarily put you to 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 wanting to take deep breaths. As a result, part of your lung may collapse or not inflate right.
Pressure from outside the lungs also may make it hard to take deep breaths. A number of 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 and clear mucus from your lungs 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 may 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 may 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.