Definition, Pathophysiologie und Epidemiologie des akuten Lungenversagens

The American-European Consensus Conference recently recommended the following criteria for diagnosis of ARDS: (1) acute onset; (2) PaO2/FiO2≤200 mmHg regardless of PEEP level; (3) bilateral infiltrates seen on frontal chest radiograph; (4) PCWP ≤ 18 mmHg when measured or no clinical evidence of left atrial hypertension. Pathophysiologically, ARDS is characterized by pulmonary edema owing to injury of the capillary-alveolar membranes and increased pulmonary artery pressure. It is further distinguished by severe hypoxemia unresponsive to the usual methods of support for respiratory failure. Hypoxemia is caused by intrapulmonary right-to-left shunting due to to persistent perfusion of non-ventilated alveoli. Another characteristic feature in ARDS is the low thoracopulmonary compliance. Latest studies suggest that the incidence of the syndrome is in the range of 3–10 cases / 100,000 inhabitants / year. Mortality rates are a major concern: old and new reports continue to report mortality rates of 50–60%.