Abstract
Background: The mechanisms linking reduced diffusing capacity of the lung for carbon monoxide (DLCO) to dyspnoea and exercise intolerance in COPD remain poorly understood.
Methods: We tested the association between peak oxygen-uptake (⩒O2) and resting physiological measures including DLCO in 300 COPD patients. We stratified the sample into tertiles of FEV1 and compared exercise responses in groups with normal and low DLCO (<lower limit of normal, LLN) using Global Lung Function Initiative reference values.
Results: DLCO was associated with peak ⩒O2, peak work-rate and dyspnoea/⩒O2 slope (all p<0.01) after adjusting for other independent variables including FEV1 and lung hyperinflation. Within tertiles, peak ⩒O2 and work-rate were lower (p<0.05) in low versus normal DLCO groups. During exercise in all tertiles, the low DLCO group had higher dyspnoea ratings, ventilation, ventilatory equivalent for carbon-dioxide and greater oxygen de-saturation and earlier respiratory mechanical limitation than normal DLCO, all p<0.05 (figure).
Conclusion: After accounting for lung mechanics, resting DLCO<LLN in patients with COPD was consistently associated with poorer exercise performance and greater dyspnoea compared with preserved DLCO. This was explained by greater pulmonary gas-exchange abnormalities, higher ventilatory demand and associated accelerated mechanical constraints.
Footnotes
Cite this article as: European Respiratory Journal 2019; 54: Suppl. 63, PA4128.
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 2019