What is atelectasis?

Updated: Oct 22, 2020
  • Author: Tarun Madappa, MD, MPH; Chief Editor: Nader Kamangar, MD, FACP, FCCP, FCCM  more...
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Atelectasis is defined as diminished volume affecting all or part of a lung. It is a partial or complete collapse of the entire lung or a specific area, or lobe, of the lung (collapsed lung). [1] Atelectasis occurs when the alveoli (small air sacs) within the lung become deflated or fill with alveolar fluid. The primary cause of acute or chronic atelectasis is bronchial obstruction by plugs of tenacious sputum; foreign bodies; endobronchial tumors; or tumors, a lymph node, or an aneurysm compressing the bronchi and bronchial distortion. It is one of the most common postoperative respiratory complications.

Pulmonary atelectasis is one of the most commonly encountered abnormalities in chest radiographs. Recognizing an abnormality due to atelectasis on chest radiographs can be crucial to understanding the underlying pathology. Several types of atelectasis exist; each has a characteristic radiographic pattern and etiology. Atelectasis is divided physiologically into obstructive and nonobstructive causes.

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