Atelectasis is a collapse of lung tissue affecting part or all of one lung. This condition prevents normal oxygen absorption by the blood as it passes through the lungs.

Atelectasis can result from an obstruction (blockage) of the airways. This causes the tiny air sacs in the lung, called alveoli, to collapse. These sacs are very thin-walled and contain a rich blood supply. Their function is to increase the surface area where the exchange of oxygen for carbon dioxide can take place as blood passes through the lungs. When the airways are blocked by a mucus plug, a foreign object, or tumor, the alveoli are unable to fill with air, and the surface area for oxygen-carbon dioxide exchange is decreased. Collapse of the alveoli can occur in any area of the lung.

Atelectasis is a potential complication following surgery, especially in people who have undergone chest or abdominal...