Lung diffusing capacity in sub-Saharan Africans versus European Caucasians

Abstract

Single breath measurements of lung diffusing capacity (DL) for carbon monoxide (CO) and nitric oxide (NO) were performed in age-, sex-, weight- and height-matched 32 sub-Saharan Africans (13 women) and 32 Caucasian Europeans, and repeated in 14 of each group at 80% of maximum exercise capacity. In Africans versus Caucasians respectively, DL_NO was 153±31 vs 176±38ml/mmHg/min at rest (P<0.001) and 210±48 vs 241±52ml/mmHg/min at exercise (P<0.01) while hemoglobin-adjusted DL_CO was 29±6 vs 34±6ml/mmHg/min at rest (P<0.001), and 46±11 vs 51±13ml/mmHg/min at exercise (P<0.01). However there were no differences in DL_CO/alveolar volume(V_A) (K_CO) and DL_NO/V_A(K_NO). The sitting-to-standing height ratio was lower in the Africans. Differences in lung volume with respect to body height explain lower DL_NO and DL_CO in sub-Saharan Africans as compared to Caucasian Europeans.

Keywords: Carbon monoxide; Exercise; Lung diffusing capacity; Lung function test; Nitric oxide; Race.