Atelectasis likely won't cause signs or symptoms if it only affects a small area of lung.
If atelectasis affects a large area of lung, especially if it occurs suddenly, it may cause a low level of oxygen in your blood. As a result, you may feel short of breath. Your heart rate and breathing rate may increase, and your skin and lips may turn blue.
Other symptoms might be related to the underlying cause of the atelectasis (for example, chest pain due to surgery).
If your child has atelectasis, you may notice that he or she seems agitated, anxious, or scared.