What's new in the "Berlin" definition of acute respiratory distress syndrome?

A valid operative definition for ARDS is essential for the appropriate institution of a standardized 'best-evidence' treatment and for the identification of subgroups of patients who may benefit from specific adjunctive interventions, as well as to assist with prognostication, resource allocation and the design of new research trials. Here, we will discuss some of the methodology used by the ARDS Definition Task Force to develop the new 'Berlin' definition of ARDS, briefly discussing the rationale for the divergence from the AECC definition. The Berlin definition improves on the predictive validity for mortality of the American-European Consensus Conference's (AECC) definition and clarifies both the conceptual model of ARDS and the definition criteria of the syndrome and of its spectrum of severity. This should facilitate case recognition and more consistent treatment strategies based on severity.