Authors/Writing Committee:V. Marco Ranieri, MD (Department of Anesthesia and Intensive Care Medicine, University of Turin, Turin, Italy); Gordon D. Rubenfeld, MD, MSc (Program in Trauma, Emergency, and Critical Care, Sunnybrook Health Sciences Center, and Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada); B. Taylor Thompson, MD (Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston); Niall D. Ferguson, MD, MSc (Department of Medicine, University Health Network and Mount Sinai Hospital, and Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada); Ellen Caldwell, MS (Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle); Eddy Fan, MD (Department of Medicine, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada); Luigi Camporota, MD (Department of Critical Care, Guy's and St. Thomas' NHS Foundation Trust, King's Health Partners, London, England); and Arthur S. Slutsky, MD (Keenan Research Center of the Li Ka Shing Knowledge Institute of St. Michael's Hospital; Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada).
The acute respiratory distress syndrome (ARDS) was defined in 1994 by the American-European Consensus Conference (AECC); since then, issues regarding the reliability and validity of this definition have emerged. Using a consensus process, a panel of experts convened in 2011 (an initiative of the European Society of Intensive Care Medicine endorsed by the American Thoracic Society and the Society of Critical Care Medicine) developed the Berlin Definition, focusing on feasibility, reliability, validity, and objective evaluation of its performance. A draft definition proposed 3 mutually exclusive categories of ARDS based on degree of hypoxemia: mild (200 mm Hg < PaO2/FIO2 ≤ 300 mm Hg), moderate (100 mm Hg < PaO2/FIO2 ≤ 200 mm Hg), and severe (PaO2/FIO2 ≤ 100 mm Hg) and 4 ancillary variables for severe ARDS: radiographic severity, respiratory system compliance (≤40 mL/cm H2O), positive end-expiratory pressure (≥10 cm H2O), and corrected expired volume per minute (≥10 L/min). The draft Berlin Definition was empirically evaluated using patient-level meta-analysis of 4188 patients with ARDS from 4 multicenter clinical data sets and 269 patients with ARDS from 3 single-center data sets containing physiologic information. The 4 ancillary variables did not contribute to the predictive validity of severe ARDS for mortality and were removed from the definition. Using the Berlin Definition, stages of mild, moderate, and severe ARDS were associated with increased mortality (27%; 95% CI, 24%-30%; 32%; 95% CI, 29%-34%; and 45%; 95% CI, 42%-48%, respectively; P < .001) and increased median duration of mechanical ventilation in survivors (5 days; interquartile [IQR], 2-11; 7 days; IQR, 4-14; and 9 days; IQR, 5-17, respectively; P < .001). Compared with the AECC definition, the final Berlin Definition had better predictive validity for mortality, with an area under the receiver operating curve of 0.577 (95% CI, 0.561-0.593) vs 0.536 (95% CI, 0.520-0.553; P < .001). This updated and revised Berlin Definition for ARDS addresses a number of the limitations of the AECC 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.
The ARDS Definition Task Force*. Acute Respiratory Distress SyndromeThe Berlin Definition. JAMA. 2012;307(23):2526–2533. doi:10.1001/jama.2012.5669