Rationale Survival from the Acute Respiratory Distress (ARDS) has been associated with clinical (e.g. age, sepsis, and organ failure) and biological factors. The latter include inflammatory mediators (e.g. cytokines), factors of activation/damage of the capillary endothelium (e.g. von Willebrand factor) and the alveolar epithelium (e.g. intracellular adhesion molecule-1), and factors associated with the coagulation/fibrinolysis cascade (e.g. protein C). These biochemical markers have been previously associated with the duration of mechanical ventilation, the ARDS-induced organ dysfunction/failure, and the survival of the patients. A combination of biochemical and clinical markers might be useful as a prognostic tool in ARDS.