Elias H Pratt1, John W Stokes2, Eddy Fan3. 1. Department of Internal Medicine, Duke University School of Medicine, Durham, NC, USA. 2. Department of Thoracic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA. 3. Interdepartmental Division of Critical Care Medicine and Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada. eddy.fan@uhn.ca.