[ARDS - An Update - Part 1: Epidemiology, Pathophysiology and Diagnosis]

The Acute Respiratory Distress Syndrome (ARDS) is defined by hypoxemic respiratory failure caused by inflammatory response within the lung usually requiring invasive mechanical ventilation. Despite more than 50 years of research numerous issues regarding epidemiology, pathophysiology and diagnosis remain unclear until today: Due to rather unspecific clinical diagnostic criteria incidence of ARDS varies considerably in clinical trials with a range from 4 to 79 cases per 100 000 persons per year. Consequently, mortality is also highly variable from about 40 to 60% in severe ARDS. Pathophysiology is mainly characterized by granulocyte infiltration of the lung thereby inducing interstitial and intra-alveolar lung edema with surfactant depletion and atelectasis formation. However, it is unknown whether pulmonary and extrapulmonary causes and risk factors for ARDS are accompanied by different pathophysiologic processes due to primary endothelial and epithelial injury. Thus, possible benefits of corresponding biomarker panels for the differentiation of endothelial and epithelial lung injury are also speculative until today. Therefore, ARDS diagnosis is still based on clinical findings and radiological imaging.