Ventilatory responses to carbon dioxide in four ethnic groups in Cape Town

Ventilatory responses to carbon dioxide (Sco2) were measured in 80 healthy adult subjects from four ethnic groups living in Cape Town. The mean Sco2 was 1.77 +/- 0.14 l/min/mmHg in whites, 1.13 +/- 0.09 l/min/mmHg in mixed race people, 0.99 +/- 0.11 l/min/mmHg in Indians and 0.87 +/- 0.10 l/min/mmHg in blacks. The difference between whites and the other three ethnic groups was highly significant (P less than 0.0001), whereas the differences between blacks, mixed race subjects and Indians were not. However, correction of Sco2 for differences in lung size, i.e. Sco2/vital capacity, eliminated the differences between whites and the other groups.