What are the causes of non-obstructed atelectasis?

Non-obstructed atelectasis occurs when there is a collapse of lung tissue not caused by a blockage in the airways. The primary causes include conditions that affect the balance of pressure within the pleural space or surfactant production, as well as overall lung function. Congestive heart failure can lead to pulmonary edema, resulting in excess fluid that interferes with gas exchange and can collapse alveoli. Pleural issues, such as pleural effusions or pneumothorax, can change the pressure dynamics in the chest cavity, causing parts of the lung to collapse. A lack of surfactant, which reduces surface tension in the alveoli, can also lead to their collapse, particularly in premature infants or in adult respiratory distress syndrome (ARDS).

Other mentioned conditions, such as infections like pneumonia, do lead to a different mechanism of lung collapse primarily due to inflammation and fluid accumulation, while blockage of airways tends to refer to obstructive atelectasis, which is distinctly different.