Pulmonary Gas Exchange Abnormalities in Patients With Mild COPD

Inclusion Criteria

• •Stable symptomatic patients with GOLD grade 1B mild COPD;
• •at least 50 years of age;
• •a cigarette smoking history ≥20 pack-years;
• •a Baseline Dyspnea Index focal score ≤9;
• •post-bronchodilator forced expiratory volume in 1 second (FEV1) ≥80 %predicted and an FEV1/forced vital capacity (FVC) ratio \<0.7 and \< lower limit of normal.