Effects of age and respiratory efforts on the perception of resistive ventilatory loads.

The present study examined the effects of age on the ability to quantitate changes in inspiratory resistive loads using signals related to the size of the load, per se. Magnitude scaling of inspiratory resistive loads was performed in different trials during breathing at small, large, and varied size tidal volumes. Subjects were specifically instructed to scale the magnitude of the airflow resistance. In both young and older adults, the perceived magnitude of a given resistance was the same in the small-, large-, and varied-sized breath trials despite substantial differences in inspiratory duration and peak inspiratory airway pressure. The change in sensation for a given change in resistance, however, was less in the older than in the younger adults. These results indicate that airflow resistance can be scaled independently of the effort used in breathing. The perception of airflow resistance is blunted in elderly adults probably as a result of an impairment in the central nervous system processing of separate signals of pressure and flow.