[Pathophysiology and differential diagnosis of dyspnea].

Dyspnea is the sensation of breathlessness, which is one of a few symptoms described as frightening and alarming. There are different hypotheses of pathophysiological mechanisms explaining a multitude of symptoms described by patients. Objective criteria for this commonly reported symptom do not exist. In general, one differentiates between dyspnea at rest and dyspnea on exertion. This article attempts to summarize the current understanding of dyspnea, explain the essential underlying pathophysiological mechanisms, discuss the broad differential diagnosis, and suggest diagnostic algorithms.