1. Section of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine; Yale School of Medicine; New Haven CT USA
2. Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Dorothy P. and Richard P. Simmons Center for Interstitial Lung Disease; University of Pittsburgh School of Medicine; Pittsburgh PA USA
3. Division of Cardiovascular Medicine, Department of Internal Medicine; Carver College of Medicine, University of Iowa; Iowa City IA USA
4. Division of Pulmonary and Critical Care Medicine; University of North Carolina; Chapel Hill NC USA