Pulmonary artery pressure in chronic obstructive pulmonary disease without resting hypoxaemia

BACKGROUND: Chronic obstructive pulmonary disease (COPD) can lead to pulmonary hypertension and cor pulmonale, which are predictors of mortality. OBJECTIVE: To identify predictors of increased pulmonary artery pressure (PAP) in COPD patients without resting hypoxaemia, and to characterise COPD patients with increased PAP. DESIGN: A study of 117 COPD patients from the Korean Obstructive Lung Disease (KOLD) cohort who had measurable tricuspid regurgitant flow under transthoracic Doppler echocardiography and no resting hypoxaemia. RESULTS: The mean patient age was 67 years. Mean forced expiratory volume in 1 second (FEV1) was 47% predicted, mean haemoglobin (Hb) concentration was 145 g/l and mean systolic PAP (sPAP) was 33 mmHg. Multiple linear regression analysis showed that Hb was the only factor independently associated with sPAP (beta = -1.752, P = 0.005). Cluster analysis using FEV ₁% predicted, sPAP and Hb concentration as variables indicated three patient clusters: Cluster 1 (n = 36; mean FEV ₁ 44% predicted, mean sPAP 39 mmHg, mean Hb 132 g/l), Cluster 2 (n = 45; FEV ₁ 35% predicted, sPAP 31 mmHg, Hb 154 g/l), and Cluster 3 (n = 36; FEV ₁ 65% predicted, sPAP 29 mmHg, Hb 148 g/l). CONCLUSION: Elevated PAP was linked to low haemoglobin levels in COPD without resting hypoxaemia.