ABSTRACT
Dyspnea, the perception of breathing discomfort, is the most common
symptom in patients with chronic obstructive pulmonary disease (COPD)
and often progresses inexorably as the disease advances. The precise neu-
rophysiological underpinnings of dyspnea are not completely understood,
but our knowledge of the ‘‘pathophysiology of dyspnea’’ has increased
considerably in recent years. Thus, the direct application of the scientific principles of psychophysics to the study of dyspnea in the clinical domain
has increased our understanding of its source and mechanisms. The emer-
gence of validated scales that measure dyspnea, during its provocation by
exercise or external loading, has been an important advance. The use of
stepwise multiple regression analysis, with dyspnea ratings (at a stand-
ardized stimulus) as the dependent variable vs. a number of relevant
physiological parameters, has allowed us to identify consistent contributory
factors. The strength of these associations has subsequently been tested by specific therapeutic manipulation. In fact, the study of mechanisms of
dyspnea relief following a number of diverse therapeutic interventions
(i.e., bronchodilators, oxygen therapy, etc.) has provided important new
insights into causation.
