Atelectasis is either complete or partial collapse of a lung.
The term refers to two distinct conditions.
The first is the failure of the lungs to expand at birth, and the second is the collapsed (airless) condition of a segment of a lung.
This collapse is generally caused by an obstruction in the tube (bronchus) leading to the lung, or by excessive secretion of mucus in the airway.
Such a condition can occur in several respiratory disorders, particularly in pneumonia but also in bronchitis.
Pressure from outside the lungs from a tumor or an expanded blood vessel (aneurysm), for example, can also press on part of a lung and cause a collapse.

Atelectasis treatment

If the cause of the collapse is a blocked bronchus, such an obstruction may be removed by using a special instrument called a bronchoscope.
Atelectasis from other causes can often be corrected by breathing exercises and respiratory therapy treatments.

Complications of atelectasis

If excessive amounts of mucus are the cause of the collapse, the mucus build-up can become infected. Atelectasis following surgery may cause a fever.