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.