Atelectasis

Atelectasis is the partial or total collapse of a lung resulting in a reduced or absent exchange of gases. Specifically it is the collapse of tiny air sacs (alveoli) in the lung. It is usually unilateral, affecting part or all of one lung. It is a condition where the alveoli are deflated down to little or no volume, as distinct from pulmonary consolidation, in which they are filled with liquid. It is often referred to informally as a collapsed lung, although it usually involves only a partial collapse. A fully collapsed lung is caused by a pneumothorax. Atelectasis is a very common finding in chest X-rays , and may be caused by a number of medical conditions, or just by normal exhalation. Acute atelectasis may occur as a post-operative complication or as a result of surfactant deficiency. In premature babies, this leads to infant respiratory distress syndrome. The term uses combining forms of atel- + ectasis, from Greek: ἀτελής, "incomplete" + Greek: ἔκτασις, "extension".