Descriptors of breathlessness in healthy individuals - Distinct and separable constructs

Study objectives: We tested the hypothesis that descriptors of breathlessne ss represent distinct and separable cognitive constructs, and predicted tha t the use of descriptors of breathlessness by healthy individuals is the sa me as their use by patients with cardiopulmonary disease. Design: Cluster analyses obtained in healthy individuals were compared with those obtained previously in patients who complained of breathing discomfo rt. In addition, we used multidimensional scaling (MDS) techniques to analy ze relationships among descriptors in healthy individuals. Setting : Public university. Participants: The participants were 100 healthy individuals (48 men and 52 women) ranging in age between 18 and 65 years (mean, 27.9 +/- 11.7 years). Measurements and results: Participants judged the dissimilarity among pairs of 15 descriptors of breathlessness that were used previously to examine t he experience of dyspnea in patients who complained of breathing discomfort . Cluster analysis solutions obtained in the healthy individuals were virtu ally identical to those obtained previously in patients. Three dimensions ( attributes) of breathing discomfort were uncovered with MDS: "Depth and fre quency of breathing," "Perceived need, or urge, to breathe," and "Difficult y breathing and phase of respiration." The results did not depend oil age, sex, levels of education, or the presence of uncomfortable awareness of bre athing with activities. Conclusions: The relations among descriptors of breathlessness obtained in healthy individuals support the contention that the association of differen t clusters,vith different disease states reflects distinct and separable co gnitive constructs that are not simply dependent on the presence of an unde rlying pathophysiology or on a specific disease condition. Our results in h ealthy individuals also suggest that distinct qualities of breathlessness r elate to different physiologic mechanisms underlying respiratory discomfort .