Detection and perception of inspiratory resistive loads in older adults with and without chronic obstructive pulmonary disease

Impairments in the detection and perception of resistive loads in healthy aging and chronic obstructive pulmonary disease (COPD) have implications for airway protection and breathlessness. This study investigated load detection and perception in 18 participants with COPD, 17 older adults [i.e., age-matched controls (AMCs)] and 23 young adults [i.e., young controls (YCs)]. Load detection was assessed as the minimal change in airway resistance that could be detected and load perception as the perceived level of effort to breathe through a series of suprathreshold resistive loads, rated on a modified Borg scale. Young and older adults, with and without COPD, could detect similar changes in resistance (∼0.7 cmH2O/L/s) and inspiratory pressure (∼0.5 cmH2O), although this equated to a smaller proportion of predicted maximal inspiratory pressure (MIPpred) for young adults (∼0.5% MIPpred) compared with older adults with and without COPD (∼1.0% MIPpred; P < 0.001). For load perception, the relationship between Borg ratings and resistance was steeper in older adult controls compared with both young adults (P < 0.001) and older adults with COPD (P < 0.01). Borg rating slopes were comparable across all participant groups with changes in inspiratory pressure. There was no correlation between load detection threshold and load perception. In older adults, heightened perception of loaded breaths with large changes in breathing resistance may be due to an increased effort to breathe at these loads.