Inclusion Criteria:  ARDS patients conforming to the Berlin Definition of Acute Respiratory Distress Syndrome ventilatory support with mechanical ventilation  Exclusion Criteria:  age < 18 years pregnancy established "Do Not Resuscitate" orders prior to enrollment acute cerebrovascular event (primary diagnosis) combined with acute coronary syndrome with myocardial infarction (primary diagnosis) acute and active gastrointestinal bleeding (primary diagnosis) requirement for immediate surgery inability to obtain written informed consent