Atelectasis is due to a disequilibrium between the ventilation of the pulmonary alveoli and their blood supply. The pulmonary alveoli cave in under the effect of a compression or obstruction of the bronchial tubes. This collapse
the entire lung or just one part of it. Atelectasis is generally caused by an illness of the respiratory passages but can also occur without an associated pathology
. To re-establish correct ventilation, a mechanical ventilation device may be installed.