Strenuous Expiratory Efforts in Some Chronic Obstructive Pulmonary Disease (COPD)

Strenuous expiratory efforts in some chronic obstructive pulmonary disease (COPD) patients limit the effectiveness of coughing. Why is this so?

A) The accessory muscles of inspiration oppose the exhalation.
B) All COPD patients have severe abdominal muscle weakness.
C) High expiratory pleural pressures compress the small airways.
D) Strenuous expiration causes the upper airway to collapse.