Perceptions and pathophysiology of dyspnea and exercise intolerance.

Dyspnea is a complex psychophysiologic sensation that requires intact afferent and efferent pathways for the full perception of the neuromechanical dissociation between the respiratory effort attempted and the work actually accomplished. The sensation is triggered or accentuated by a variety of receptors located in the chest wall, respiratory muscles, lung parenchyma, carotid body, and brain stem. The sensation of dyspnea is stronger in patients with higher scores for anxiety and has been reported in patients with anxiety disorders with no cardiopulmonary disease. These observations demonstrate the importance of cerebral cognition in this complex symptom. Ten cases are presented that illustrate different clinical manifestations of dyspnea.