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 is one of the most common breathing (respiratory) complications after surgery. Atelectasis is also a possible complication of other respiratory problems, including cystic fibrosis, inhaled foreign objects, lung tumors, fluid in the lung, severe asthma and chest injuries.

The amount of lung tissue involved in atelectasis is variable, depending on the cause. Signs and symptoms of atelectasis also vary. Atelectasis can be serious because it reduces the amount of oxygen available to your body. Treatment depends on the cause and severity of the collapse.

Symptoms Causes Risk factors Complications Prevention

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

  • Difficulty breathing (dyspnea)
  • Rapid, shallow breathing
  • Coughing
  • Low-grade fever

When to see a doctor

Significant atelectasis is likely to occur when you're already in a hospital. However, see your doctor 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 undergoes surgery has some atelectasis from anesthesia. Anesthesia changes the dynamics of airflow within the lungs, the absorption of gases and pressures, all of which combine to cause some degree of collapse of the tiny air sacs (alveoli) in your lungs. It is particularly prominent after heart bypass surgery.

A blockage in your air passages (bronchial tubes) can cause obstructive atelectasis. Possible causes of blockage include:

  • Mucus plug. Accumulation of mucus in your airways, often occurring during and after surgery because you can't cough, is the most 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. This is why it's important to breathe and cough deeply during your recovery. Expanding the lungs gets air around the mucus plugs and makes them easier to cough out. Mucus plugs also are common in people with cystic fibrosis and during severe asthma attacks.
  • Foreign body. Children are most likely to inhale 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 inflammation of your lungs, temporarily can cause atelectasis. An atelectatic lung that remains collapsed for a few weeks or more can result in bronchiectasis (brong-key-EK-tuh-sis), a condition in which damage to the airways causes them to widen and become flabby and scarred.
  • 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.

Factors that increase the risk of atelectasis include:

  • Premature birth, if the lungs aren't fully developed
  • Impaired swallowing function, particularly in older adults — aspirating secretions into the lungs is a major source of infections
  • Any condition that interferes with spontaneous coughing, yawning and sighing
  • Lung disease, such as asthma, bronchiectasis or cystic fibrosis
  • Confinement to bed, with infrequent change of position
  • Abdominal or chest surgery
  • Recent general anesthesia
  • Shallow breathing — a result of abdominal pain or rib fracture, for example
  • Respiratory muscle weakness, due to muscular dystrophy, spinal cord injury or another neuromuscular condition
  • Obesity — fat in the abdomen can elevate your diaphragm and hamper your ability to inhale fully
  • Age — being a young child between the ages of 1 and 3

The following complications may result from atelectasis:

  • Low blood oxygen (hypoxemia). Atelectasis hampers your lungs' ability to get oxygen to the alveoli.
  • Lung scarring. Some damage or scarring may remain after the lung is reinflated, resulting in bronchiectasis.
  • Pneumonia. You're at greater risk of developing pneumonia until the atelectasis has been cleared. The mucus in a collapsed lung is a breeding ground for bacterial infections.
  • Respiratory failure. A small area of atelectasis, especially in an adult, usually is treatable. But a large area, particularly in an infant or in someone with lung disease, can be life-threatening.

To decrease atelectasis risk:

  • Be careful with small objects. Don't give children nuts until they are about 3 years old, when they have molars to more thoroughly chew nuts. And be careful about allowing young children to play with toys that have small, loose pieces.
  • Stop smoking. Smoking increases mucus production and damages the small, hair-like structures that line the bronchial tubes (cilia). Their wave-like motion helps carry mucus out of your airways.
  • Do deep-breathing exercises. After surgery, follow your doctor's instructions for frequent coughing and doing deep-breathing exercises.
  • Reposition yourself. If you must stay in bed, change your position frequently. Get up and walk as soon as you're able.
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