E Wesley Ely1, Pratik P Pandharipande2. 1. Division of Allergy and Pulmonary Critical Care Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee2Veterans Affairs Tennessee Valley Health Care System, Nashville, Tennessee3VA Geriatric Research, Education, a. 2. Division of Anesthesiology Critical Care Medicine, Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee.