Atelectasis is an area of the lung that is not completely inflated.
In atelectasis in newborns (fetal atelectasis), the lungs do not expand
normally at birth. Reasons for this happening include premature birth (being
born too early), lack of oxygen, and airway blockage.
In adults, atelectasis may be the result of airway blockage or of
not breathing deeply (after surgery or because of neuromuscular disease).
Because atelectasis is known to occur most commonly as a complication after
surgery, deep breathing is often used to prevent or treat it. Mild atelectasis
is not usually a problem. But when atelectasis is severe, it can cause pain
and/or shortness of breath. And it can lower oxygen levels.
Atelectasis is treated by restoring airflow to the lung and by
removing any blockage.