By Mayo Clinic Staff

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.

June 11, 2015