Lung diffusing capacity in sub-Saharan Africans versus European Caucasians

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, DLNO was 153 ± 31 vs 176 ± 38 ml/mmHg/min at rest (P < 0.001) and 210 ± 48 vs 241 ± 52 ml/mmHg/min at exercise (P < 0.01) while hemoglobin-adjusted DLCO was 29 ± 6 vs 34 ± 6 ml/mmHg/min at rest (P < 0.001), and 46 ± 11 vs 51 ± 13 ml/mmHg/min at exercise (P < 0.01). However there were no differences in DLCO/alveolar volume(VA) (KCO) and DLNO/VA(KNO). The sitting-to-standing height ratio was lower in the Africans. Differences in lung volume with respect to body height explain lower DLNO and DLCO in sub-Saharan Africans as compared to Caucasian Europeans.