Adhesive atelectasis is primarily caused by what factor?

• A. Fluid accumulation in the alveoli
• B. Surfactant impairment
• C. Airway blockage
• D. External compression

Answer: (B)

Adhesive atelectasis is primarily associated with surfactant impairment. Surfactant is a substance produced by the type II alveolar cells in the lungs that reduces surface tension within the alveoli, preventing collapse during expiration. When surfactant levels are low or dysfunctional, the surface tension in the alveoli increases, leading to difficulty in maintaining their open state. This results in the collapse of lung units and consequently adhesive atelectasis, where adjacent alveoli adhere to each other due to the loss of surface tension-reducing properties of surfactant.

In contrast, fluid accumulation in the alveoli typically leads to conditions such as pulmonary edema, which can also contribute to atelectasis but through different mechanisms. Airway blockage often results in obstructive atelectasis, where there is an accumulation of mucus or a foreign body obstructing the airways. External compression pertains to a physical force from outside the lungs causing collapse, such as a pleural effusion or lung mass. While these factors can lead to atelectasis, they do not specifically describe the mechanism of adhesive atelectasis, which is fundamentally linked to the dysfunction of surfactant.