1. Division of Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts;
2. Medical Service, VA Ann Arbor Healthcare System, Ann Arbor, Michigan;
3. Division of Pulmonary and Critical Care Medicine, University of Michigan, Ann Arbor, Michigan;
4. Division of Pulmonary Critical Care and Sleep Medicine, National Jewish Health, Denver, Colorado;
5. University of Colorado, Denver, Colorado;
6. Section of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, College of Medicine, Baylor University, Houston, Texas;
7. Department of Medicine, National Heart and Lung Institute, Imperial College London, London, United Kingdom; and
8. Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska