[The first 24 hours: acute dyspnea].

Acute dyspnea is a common presentation in the emergency department. Immediate diagnostic strategy and efficient management is crucial. Therefore, a diagnostic work up consisting of a brief medical history, physical examination and technical investigations, including laboratory tests, is presented. Identification of the cardio-vascular, pulmonary or other etiology enables the initiation of adequate therapy. This is outlined in detail for three common entities.