Reduced six-minute walking distance, high fat-free-mass index and hypercapnia are associated with endothelial dysfunction in COPD.

This study investigated the determinants of endothelial function in patients with chronic obstructive pulmonary disease (COPD). Digital pulse amplitude augmentation was measured by post-ischemic reactive hyperemia (RH-PAT) in 44 COPD patients and analyzed with covariates: condition vs. exacerbation, fat-free mass index (FFMI), pulmonary function, blood pressure, inflammation, six-minute walking distance, muscle function, medications, diabetes and prevalent cardiovascular diseases. RH-PAT was 0.43 (-0.14 to 1.30) with 50% of patients exhibiting abnormal RH-PAT ≤ 0.40. After adjustment for age and sex, RH-PAT was linked to condition, FFMI, myocardial infarction history, FEV(1), PaCO(2), heart rate, bicarbonates, inflammation and walking distance (p<0.10). In multivariate analysis, walking distance, FFMI and PaCO(2) were independent contributors of RH-PAT explaining 49% of the variance (p<0.0001). Higher FFMI was associated with higher inflammation, oxidative stress and endothelial dysfunction. Six-minute walking distance which is a widely available marker of severity and functional capacity in COPD patients is a main predictor of endothelial dysfunction.