A 150 lb., 62-year-old man had a chronic productive cough, exertional dyspnea, mild cyanosis, and marked slowing of forced expiration. His pulmonary function and laboratory tests follow:
Frequency: 16 breaths/min
Alveolar ventilation: 4.2 L/min
Vital capacity (VC): 2.2 L
Functional residual capacity (FRC): 4.0 L
Total lung capacity (TLC): 5.2 L
Maximum inspiratory flow rate: 250 L/min
Maximum expiratory flow rate: 20 L/min
PaO2: 62 mm Hg
PaCO2: 39 mm Hg
Pulmonary function tests after bronchodilator therapy:
Frequency: 16 breaths/min
Alveolar ventilation: 4.35 L/min
VC: 2.4 L
FRC: 4.0 L
TLC: 5.2 L
Maximum inspiratory flow rate: 250 L/min
Maximum expiratory flow rate: 23 L/min
PaO2: 62 mm Hg
PaCO2: 38 mm Hg
What is the cause of this altered RV?