1. A.J. Pawlik, PT, DPT, CCS, Cardiac and Pulmonary Rehabilitation, Department of Therapy Services, University of Chicago Medical Center, 5841 S Maryland Ave, MC 1081, W109, Chicago, IL 60637-1470 (USA).
2. J.P. Kress, MD, Department of Medicine, Section of Pulmonary and Critical Care, University of Chicago Medical Center.