Which condition is associated with decreased lung compliance?

Which condition is associated with decreased lung compliance?

• A. ARDS
• B. Emphysema
• C. Asthma
• D. Pneumonia

Answer: (A)

Lung compliance is a measure of how easily the lungs can expand in response to pressure. Decreased compliance means the lungs are stiff and difficult to inflate, so higher inspiratory pressures are needed for the same tidal volume. Acute respiratory distress syndrome causes widespread alveolar damage, edema, and collapse of air spaces, along with surfactant dysfunction. This makes the lung tissue less distensible overall, sharply lowering its compliance. Emphysema, on the other hand, involves destruction of elastic tissue and tends to increase compliance, leading to more easily distensible, though often hyperinflated, lungs. Asthma is mainly an airway obstruction with increased resistance rather than a rigid chest-lung unit, so static compliance isn’t characteristically reduced. Pneumonia can reduce compliance where consolidation occurs, but ARDS produces a global stiffening of the lung that most clearly reduces compliance. Thus, the condition most associated with decreased lung compliance is ARDS.

Lung compliance is a measure of how easily the lungs can expand in response to pressure. Decreased compliance means the lungs are stiff and difficult to inflate, so higher inspiratory pressures are needed for the same tidal volume.

Acute respiratory distress syndrome causes widespread alveolar damage, edema, and collapse of air spaces, along with surfactant dysfunction. This makes the lung tissue less distensible overall, sharply lowering its compliance. Emphysema, on the other hand, involves destruction of elastic tissue and tends to increase compliance, leading to more easily distensible, though often hyperinflated, lungs. Asthma is mainly an airway obstruction with increased resistance rather than a rigid chest-lung unit, so static compliance isn’t characteristically reduced. Pneumonia can reduce compliance where consolidation occurs, but ARDS produces a global stiffening of the lung that most clearly reduces compliance.

Thus, the condition most associated with decreased lung compliance is ARDS.