Effect of aging on respiratory responses to CO2 and inspiratory resistive loads.

We studied 10 elderly individuals over 60 years of age and 18 individuals less than 30 years to determine whether aging affects the response of the respiratory control system to chemical stimuli or to altered mechanical conditions. Both groups consisted of males and females who were nonsmokers. Ventilation and the isometric force developed by the inspiratory muscles (occlusion pressure) was assessed during hypercapnia while the subjects breathed under control conditions or through a load at the mouth that increased inspiratory resistance. Ventilation responses to progressively increasing CO2 were lower but not significantly so in the older group. There were significant differences in ventilatory pattern in the two groups. However, occlusion pressure responses to hypercapnia and to resistive loads were the same. The results suggest that aging has little or no adverse effect on respiratory control.