Abstract
Background: DLCO is modestly associated with emphysema in mild-moderate COPD. Whether low DLCO is associated with reduced pulmonary total blood volume (TBV) and ventilatory inefficiency, independent of emphysema, is unknown.
Methods: We performed lung function, incremental exercise test and quantitative chest computed tomography (QCT) in 65 smokers with no or mild-moderate airflow obstruction. TBV was calculated for the entire segmented vascular tree (VIDA Apollo). Smokers were dichotomized based on emphysema extent using the median CT low attenuation percent: trace (0.1-2.1% (<-950 HU)) and mild (2.2-19.5%). Each subgroup was evaluated for low and normal DLCO (GLI equation).
Results: Groups were matched for age, sex, and FEV1. Smoking history (pack-years) was 39±30 vs. 49±7 and 35±20 vs. 30±19 (mean±SD), for normal vs. low DLCO in trace and mild emphysema subgroups, respectively. Within emphysema subgroups (Figure), low DLCO was associated with greater ventilatory equivalent for CO2 (⩒E/⩒CO2) nadir during exercise and lower TBV on QCT (p<0.05). In all smokers, DLCO (but not emphysema extent) was associated with TBV (r=0.23, p=0.04) and ⩒E/⩒CO2 nadir (r=-0.62, p<0.01).
Conclusion: In smokers with “largely mild" emphysema, low resting DLCO was associated with reduced CT pulmonary blood volume and increased exercise ventilatory inefficiency, independent of airflow obstruction and emphysema severity.
Footnotes
Cite this article as: European Respiratory Journal 2021; 58: Suppl. 65, OA2555.
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