International panel updates definition of acute respiratory distress syndrome

Gordon D. Rubenfeld, M.D., of the Sunnybrook Health Sciences Center, Toronto, Canada, and colleagues with the ARDS (acute respiratory distress syndrome) Definition Task Force, developed a new definition of ARDS (the Berlin Definition) that focused on feasibility, reliability, validity and objective evaluation of its performance.

ARDS is a life-threatening lung condition that prevents enough oxygen from getting to the lungs and into the blood. Among the changes the panel proposed was a draft definition with 3 mutually exclusive categories of mild, moderate, and severe ARDS based on degree of hypoxemia (insufficient oxygenation of the blood) and four ancillary variables for severe ARDS. Using the Berlin Definition, stages of mild, moderate, and severe ARDS were associated with increased mortality (27 percent; 32 percent; and 45 percent, respectively), and increased median duration of mechanical ventilation in survivors.

The authors write that compared with the previous definition for ARDS, the final Berlin Definition had better predictive validity for mortality. "This updated and revised Berlin Definition for ARDS addresses a number of the limitations of the [previous] definition. The approach of combining consensus discussions with empirical evaluation may serve as a model to create more accurate, evidence-based, critical illness syndrome definitions, and to better inform clinical care, research, and health services planning."