Overview

Atelectasis (at-uh-LEK-tuh-sis) is a complete or partial collapse of the entire lung or area (lobe) of the lung. It occurs when the tiny air sacs (alveoli) within the lung become deflated or possibly filled with alveolar fluid.

Atelectasis is one of the most common breathing (respiratory) complications after surgery. It's also a possible complication of other respiratory problems, including cystic fibrosis, lung tumors, chest injuries, fluid in the lung and respiratory weakness. You may develop atelectasis if you breathe in a foreign object.

Atelectasis can make breathing difficult, particularly if you already have lung disease. Treatment depends on the cause and severity of the collapse.