Cognitive und affective representation of respiratory sensations in health and respiratory disease

Background Dyspnea is a multidimensional construct with qualitatively distinct types of breathlessness that can be distinguished by healthy and diseased individuals. The report of unique sets of these qualitatively distinct respiratory sensations has been shown to be characteristic for specific pathophysiological conditions in a variety of somatic and psychological disorders (Manning & Schwartzstein, 1995). Qualities of physiological sensations cannot be measured other than by self-report of the person who experiences them (e.g. Davenport, 2002). Therefore, the cognitive representation of respiratory sensations has been investigated intensively in recent research. However, sensation report has mostly been analyzed on the level of single sensation descriptors and a direct comparison of the structure of sensation report between healthy and diseased individuals is missing. Furthermore, while discomfort associated with the experience of dyspnea in general has been investigated intensively in recent research (e.g. Wilson & Jones, 1991), little is known about the affective evaluation of specific sensations and dimensions underlying dyspnea-report and on the question how separate sensory and affective dimensions of dyspnea are. Aims In this doctoral project, we compared the structure of dyspnea report between individuals with different experiential background regarding breathlessness, such as healthy and diseased individuals, and younger and older individuals. We explored the structure of self-report by integrating clusters of respiratory sensations within a framework of latent dimensions of dyspnea. Besides the cognitive structure of the language of dyspnea, we explored the affective evaluation of clusters and latent dimensions of dyspnea-report in health and disease. We hypothesize that in the cognitive representation of dyspnea, groups of respiratory sensation descriptors can be found that correspond with the activation of different breathing pattern induced by different experimental breathing challenges. Furthermore, we expect that individuals with different experiential backgrounds regarding dyspnea vary in their cognitive representation and affective evaluation of specific respiratory sensations, reflecting different mechanisms of dyspnea in health and disease. Moreover, we hypothesize that affective and sensory components of breathlessness are not separate, but that each sensory experience can be located on an affective dimension between pleasant and unpleasant breathing. Latent sensory dimensions of dyspnea are assumed to contribute simultaneously to the feeling of discomfort associated with breathlessness. Methods In four studies, we analyzed the report of respiratory sensations after experimental induction of dyspnea as well as in retrospection and compared the cognitive and affective representation of respiratory sensations between younger and older healthy individuals and individuals suffering from respiratory disease. In contrast to prior approaches, we restricted the methods of our analysis not to either cluster analysis or Multidimensional Scaling (MDS), but combined MDS, cluster analysis, and Preference Mapping to explore the language of dyspnea. Results The report of respiratory sensations was corresponding with breathing pattern induced by respiratory challenges. Our results suggest that the complexity of sensation report has been underestimated in prior research. Fewer, but more complex types of dyspnea might be more appropriate to describe the structure of dyspnea. The cognitive representation and affective evaluation of respiratory sensations varied between groups of individuals reflecting different mechanisms and consequences of dyspnea in health, aging and disease. Not all respiratory sensations commonly subsumed under dyspnea are necessarily perceived as uncomfortable by healthy individuals. We found stability of subordinated clusters of respiratory sensations to be limited. Dimensions of dyspnea found with MDS provide a more reliable picture of the structure of dyspnea report than cluster solutions across populations and studies. We found a three dimensional structure with 1) fit between need for air and actual breathing, 2) effort, and 3) attempt of voluntary control as underlying dimensions of dyspnea report. Results found with Preference Mapping suggest that in individuals with and without reported respiratory disease the dimensions fit and effort contribute equally to the experience of discomfort. In older individuals, we found an age related decrease in the differentiation between qualities of dyspnea. Conclusion While it has been emphasized a number of times how important it is to listen to what patients say about their disease (Davenport, 2002), this listening might be especially challenging in the language of dyspnea. The interpretation and evaluation of language descriptors of respiratory sensations is highly dependent on the experiential background of the person reporting dyspnea and the context in which these sensations are elicited. Latent dimensions of dyspnea have been found to be less affected by variations in interpretation and evaluation of language descriptors and could help to assess comparability of sensation report between groups with different experiential background regarding breathlessness.