Behavior of the Pulmonary Circulation in Chronic Obstructive Pulmonary Disease

The hemodynamics of the pulmonary circulation were examined in 28 patients with severe and stable chronic obstructive pulmonary disease (COPD) who were born and raised at high altitude (2,240 meters) (COPD-A). All patients had mean pulmonary pressures (PAP) greater than 16 mmHg. We observed: (1) a low correlation between pulmonary arterial diastolic pressure (PAd) and arterial oxygen saturation (r = 0.38, p < 0.05); (2) similar PAP in patients with COPD living at sea level (COPD-S) and patients with COPD-A (COPD-S, 32 ± 7 mmHg; COPD-A, 27.5 ± 11 mmHg; p = NS), despite more unsaturation in patients with COPD-A (COPD-S, 84.6 ± 6%; COPD-A, 77.5 ± 9%; p < 0.05) and similar arterial pH; (3) lower levels of PAP in COPD-A (COPD-S, 51.7 ± 10 mmHg; COPD-A, 33.6 ± 12 mmHg; p < 0.001) for the same degree of unsaturation (COPD-S, 71 ± 6%; COPD-A, 71 ± 8%; p = NS) and a lower arterial pH in COPD-S (COPD-S, 7.34 ± 0.03; COPD-A, 7.39 ± 0.04; p < 0.01). We conclude that pulmonary hypertension caused by chronic alveolar h...