Dyspnea and Respiratory Compensation Response to Resistive Loading in Elderly Humans
Compensatory mechanisms in response to respiratory mechanical loading involve various steps in the control of breathing.1 These include changes in the intrinsic properties of the respiratory muscles, reflexes from mechanoreceptors in the thorax, lungs and airways, and the chemoreceptor reflexes. In addition, conscious appreciation of the load in the higher brains is implicated as a behavioral component of respiratory compensation to loading. Tack and coworkers reported, using the magnitude-estimation method, that the respiratory sensation of resistive loads as well as elastic ones is diminished in elderly healthy subjects.2, 3 However, effects of aging on the load compensation reflex and the sensation of dyspnea have not been simultaneously studied. To examine this, we studied, in healthy volunteers, the ventilatory and occlusion pressure responses to progressive hypercapnia with and without inspiratory flow-resistive loading while the intensity of dyspnea was simultaneously assessed by visual analogue scaling.
KeywordsRespiratory Muscle Resistive Loading Ventilatory Response Occlusion Pressure Respiratory Sensation
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