Atelectasis refers to which condition?

• A. Collapsed lung
• B. Inflammation of lung tissue
• C. Air in the pleural space
• D. Fluid in the alveoli

Answer: (A)

Atelectasis is a region of the lung that has collapsed and become airless, so those alveoli are not participating in gas exchange. This happens when the airways are obstructed (often by mucus plugs or secretions) or when the lung tissue is compressed, preventing full expansion. Because the core issue is loss of aeration in part of the lung, it is described as a collapsed section of the lung rather than a primary inflammation, air in the pleural space, or fluid filling the alveoli.

In contrast, inflammation of lung tissue refers to conditions like pneumonia where the alveoli become filled with inflammatory cells and fluid; air in the pleural space describes a pneumothorax, where air accumulates between the lung and chest wall causing collapse; and fluid in the alveoli points to edema or other processes that fill the alveolar spaces with fluid. Atelectasis specifically denotes the deflated, non-aerated lung tissue that reduces usable lung volume and gas exchange. Treatments emphasize re-expanding the affected area through deep breathing, coughing, incentive spirometry, and mobilization.