Which condition is associated with increased lung compliance?

Which condition is associated with increased lung compliance?

• A. Pulmonary edema
• B. Emphysema
• C. ARDS
• D. Pneumonia

Answer: (B)

Lung compliance is how easily the lungs expand for a given change in pressure (ΔV/ΔP). In emphysema, destruction of alveolar walls and loss of elastic recoil make the lungs more distensible—they expand more easily for the same pressure, so compliance increases. This means inflation is easier, but exhalation is less efficient due to reduced elastic recoil, leading to air trapping and hyperinflation. Pulmonary edema, ARDS, and pneumonia all stiffen the lungs: fluid, inflammation, and edema increase elastic resistance and decrease compliance. Hence, the condition associated with increased lung compliance is emphysema.

Lung compliance is how easily the lungs expand for a given change in pressure (ΔV/ΔP). In emphysema, destruction of alveolar walls and loss of elastic recoil make the lungs more distensible—they expand more easily for the same pressure, so compliance increases. This means inflation is easier, but exhalation is less efficient due to reduced elastic recoil, leading to air trapping and hyperinflation.

Pulmonary edema, ARDS, and pneumonia all stiffen the lungs: fluid, inflammation, and edema increase elastic resistance and decrease compliance. Hence, the condition associated with increased lung compliance is emphysema.