Atelectasis (at-uh-LEK-tuh-sis) — a complete or partial collapse of a lung or lobe of a lung — develops when the tiny air sacs (alveoli) within the lung become deflated. It's a breathing (respiratory) complication after surgery.

Atelectasis is also a possible complication of other respiratory problems, including cystic fibrosis, inhaled foreign objects, lung tumors, fluid in the lung, respiratory weakness and chest injuries.

The amount of lung tissue involved in atelectasis is variable, depending on the cause. Atelectasis can make breathing difficult and lower oxygen particularly if lung disease is already present. Treatment depends on the cause and severity of the collapse.


There may be no obvious signs or symptoms of atelectasis. If you do have signs and symptoms, they may include:

  • Difficulty breathing (dyspnea)
  • Rapid, shallow breathing
  • Coughing

When to see a doctor

Atelectasis is likely to occur when you're already in a hospital. However, seek medical attention right away if you have trouble breathing. Other conditions besides atelectasis can cause breathing difficulties and require an accurate diagnosis and prompt treatment. If your breathing becomes increasingly difficult, seek emergency care.


Atelectasis may be the result of a blocked airway (obstructive) or of pressure from outside the lung (nonobstructive).

Almost everyone who has surgery has some atelectasis from anesthesia. Anesthesia changes your regular pattern of breathing and the absorption of gases and pressures, which may combine to cause some degree of collapse of the tiny air sacs (alveoli) in your lungs. Atelectasis is particularly prominent after heart bypass surgery.

Obstructive atelectasis may be caused by:

  • Mucus plug. Accumulation of mucus in your airways, often occurring during and after surgery because you can't cough, is a common cause of atelectasis. Drugs given during surgery make the lungs inflate less fully than usual, so normal secretions collect in the airways. Suctioning the lungs during surgery helps clear away these secretions, but they may continue to build up afterward. Mucus plugs also are common in children, people with cystic fibrosis and during severe asthma attacks.
  • Foreign body. Atelectasis is common in children who have inhaled an object, such as a peanut or small toy part, into their lungs.
  • Narrowing of major airways from disease. Chronic infections, including fungal infections, tuberculosis and other diseases, can scar and constrict major airways.
  • Tumor in a major airway. An abnormal growth can narrow the airway.
  • Blood clot. This occurs only if there's significant bleeding into the lungs that can't be coughed out.

Possible causes of nonobstructive atelectasis include:

  • Injury. Chest trauma — from a fall or car accident, for example — can cause you to avoid taking deep breaths (due to the pain), which can result in compression of your lungs.
  • Pleural effusion. This is a buildup of fluid between the tissues (pleura) that line the lungs and the inside of the chest wall.
  • Pneumonia. Different types of pneumonia, an infection of your lungs, may temporarily cause atelectasis.
  • Pneumothorax. Air leaks into the space between your lungs and chest wall, indirectly causing some or all of a lung to collapse.
  • Scarring of lung tissue. Scarring could be caused by injury, lung disease or surgery. In these rare cases, the atelectasis is minor compared with the damage to the lung tissue from the scarring.
  • Tumor. A large tumor can press against and deflate the lung, as opposed to blocking the air passages.

Risk factors

Factors that increase the risk of atelectasis include:

  • Age — being younger than 3 or older than 60 years of age.
  • Any condition that interferes with spontaneous coughing, yawning and sighing.
  • Confinement to bed with infrequent changes of position.
  • Impaired swallowing function, particularly in older adults — aspirating secretions into the lungs is a major source of infections.
  • Lung disease, such as asthma in children, COPD, bronchiectasis or cystic fibrosis.
  • Premature birth.
  • Recent abdominal or chest surgery.
  • Recent general anesthesia.
  • Respiratory muscle weakness, due to muscular dystrophy, spinal cord injury or another neuromuscular condition.
  • Any cause of shallow breathing — including medications and their side effects, or mechanical limitations, such as abdominal pain or rib fracture, for example.


The following complications may result from atelectasis:

  • Low blood oxygen (hypoxemia). Atelectasis hampers your lungs' ability to get oxygen to the alveoli.
  • Pneumonia. You're at greater risk of developing pneumonia until the atelectasis has been cleared. Mucus in a collapsed lung may lead to infection.
  • Respiratory failure. A small area of atelectasis, especially in an adult, usually is treatable. But loss of a lobe or a whole lung, particularly in an infant or in someone with lung disease, can be life-threatening.


Atelectasis in children is often caused by a blockage in the airway. To decrease atelectasis risk, keep small objects out of reach of children.

In adults, atelectasis most commonly occurs after surgery. If you're scheduled for surgery, talk with your doctor about how to reduce your risk of atelectasis.

June 11, 2015
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