[Dyspnea. I. Definition and pathophysiological problems].
An analytical review was made on the pathophysiological mechanisms suspected to be involved in dyspnea, accepting that the sensation of shortness of breathing, and the subjective signs (exertion, anxiety and fear) are essential for the diagnosis of this condition. Bearing in mind the anatomical relations in the central nervous system between the structures involved in the control and regulation of the respiration, and these involved in the emotions, a scheme was presented of the pathophysiological mechanisms, which determine the essential signs of the dyspnea. Three neuronal circuits were assumed for the explanation of the manifestations in dyspnea: subjective signs, symptoms of the thoraco-pulmonary and cardio-vascular systems, and these of the voluntary muscular system that accompanied dyspnea.