This type of atelectasis occurs due to external forces compressing the alveoli. What type is this?

• A. Adhesive
• B. Contraction
• C. Compression
• D. Resorption

Answer: (C)

The type of atelectasis referred to in the question is indeed compression atelectasis. This condition occurs when external forces, such as fluid, air, or masses, exert pressure on the lung tissue, leading to the collapse of the alveoli. This can happen in situations such as pleural effusion, pneumothorax, or large tumors that push against the lung, thereby preventing normal expansion during inhalation. The external pressure causes the alveoli to collapse, reducing lung capacity and impairing gas exchange.

Understanding the mechanisms of atelectasis is crucial in pulmonary pathophysiology. Compression atelectasis is distinct from other types, such as adhesive atelectasis, which involves surfactant deficiency preventing alveolar expansion; contraction atelectasis, which is due to fibrosis or scarring that physically retracts the lung tissue; and resorption atelectasis, which occurs when an obstruction prevents air from reaching the alveoli, leading them to collapse as the absorbed gases cannot be replenished. Each type has different underlying causes and clinical implications, highlighting the importance of identifying the specific mechanism at play in a patient’s lung pathology.