Atelectasis is the lack of gas exchanging within alveoli, due to alveolar collapse or fluid consolidation. It may affect part or all of one lung. It is a condition where the alveoli are deflated.

Brookelyn developed atelectasis after coming off the ventilator. She had been on the ventilator many time and never developed this and one time she was having trouble trying to breath after being extubated. She was treated by getting scheduled nebulizer treatments along with around the clock oxygen. She was recovered in two to three days.