Abstract
Rationale: Pulmonary hypertension (PH) is a frequent complication of chronic obstructive pulmonary disease (COPD), usually presenting as mild-moderate (MPH) and less often as severe PH (SPH), which is characterised by mild airflow obstruction and severe hypoxemia. To what extent the pulmonary vascular derangement is the cause or consequence of gas exchange impairment in COPD with SPH is unknown. We evaluated arterial PO2 (PaO2) determinants in COPD, grouped by hemodynamic PH classification (Nathan S et al, Eur Respir J 2019).
Methods: we divided 190 COPD patients with right heart catheterization into three groups: COPD with NoPH (n=91); COPD with MPH (n=61) (mean pulmonary artery pressure, mPAP 21-24 with pulmonary vascular resistance, RVP, ≥3 WU or mPAP ≥25 mmHg); and COPD with SPH (n=38, mPAP ≥35 mmHg; or mPAP ≥25 mmHg with cardiac index, CI <2 L/min/m2). We compared lung function tests, pulmonary hemodynamics, PaO2 and mixed venous (PvO2) gases. In 88 patients (41 NoPH, 40 MPH, 7 SPH) ventilation-perfusion (VA/Q) ratio distributions (inert gas elimination technique, MIGET) were also assessed.
Results: COPD patients with SPH had less ventilatory impairment (FEV1 66%pred vs 42 in COPD with NoPH and 33 in COPD with MPH), worse PaO2 (48 vs 73 and 62 mmHg), PvO2 (33 vs 36 and 35 mmHg) and VA/Q mismatch, greater shunt and increased dispersion of blood flow distribution (LogSD Q).
Conclusions: In COPD with SPH, hypoxemia results from the combined effects of greater VA/Q mismatch, reduced PvO2 from lower cardiac output, and the interaction of both. Accordingly, in COPD patients with severe PH, vascular abnormalities may be the cause, rather than a consequence, of abnormal pulmonary gas exchange.
Funded by SEPAR and SOCAP
Footnotes
Cite this article as: European Respiratory Journal 2021; 58: Suppl. 65, PA1926.
This abstract was presented at the 2021 ERS International Congress, in session “Prediction of exacerbations in patients with COPD”.
This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).
- Copyright ©the authors 2021