Question

Compliance is decreased in all except:

• A. Pulmonary congestion
• B. COPD
• C. Decreased surfactant
• D. Pulmonary fibrosis

Hint:

Loss of elastic recoil in emphysema makes the lung easier, not harder, to inflate.

Answer 1

The Correct Option is B

Step 1: Lung compliance is the change in lung volume per unit change in pressure; it reflects how easily the lung distends. Stiffer lungs have low compliance; floppier, less elastic lungs have high compliance.
Step 2: Pulmonary congestion (option 1) fills the interstitium and alveoli with fluid, making the lung stiff and lowering compliance.
Step 3: Decreased surfactant (option 3) raises alveolar surface tension and increases the tendency to collapse, which reduces compliance (as in respiratory distress syndrome).
Step 4: Pulmonary fibrosis (option 4) deposits collagen and scar tissue, making the lung rigid and markedly lowering compliance, the classic restrictive pattern.
Step 5: COPD, especially emphysema, destroys alveolar walls and elastic tissue. Loss of elastic recoil makes the lung easier to inflate, so compliance is increased, not decreased. Therefore COPD is the exception.
Conclusion: The answer is option 2 (COPD).