Patient characteristics
| Characteristics | Values |
| Subjects | 39 |
| Age yrs | 54±13 |
| Sex | |
| Male | 27 (69.2) |
| Female | 12 (30.8) |
| Systolic BP mmHg | 124.2±17.4 |
| Diastolic BP mmHg | 81.1±7.2 |
| Abnormal ECG# | 14 (36) |
| FEV1/VC | 58.9±19.3 |
| DL,CO/VA | 3.5±0.9 |
| Pa,CO2 mmHg | 39.9±5.8 (21.2–67.3) |
| Pa,O2 mmHg | 61.8±7.9 (37.8–86.2) |
Data are presented as mean±sd (range) or n (%). BP: blood pressure; ECG: electrocardiogram; FEV1: forced expiratory volume in one second; VC: vital capacity; DL,CO: single-breath diffusion capacity of the lung for carbon monoxide; VA: alveolar volume; Pa,CO2: arterial carbon dioxide tension; Pa,O2: arterial oxygen tension;. #: ECG was considered abnormal if right-axis deviation, right bundle branch block, right ventricular hypertrophy, or P-pulmonale was present.