Pulmonary and Critical Care Medicine, Evanston-Northwestern Healthcare and Northwestern University Medical School, Evanston, Illinois; Respiratory and Critical Care Medicine, College of Medicine, Department of Pharmacy Practice, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois; VA Health Care System, West Side Division, Chicago, Illinois; and Research Service, Southern Arizona VA Health Care System, Tucson, Arizona (At 2001-09-01)