1Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA. 2Department of Medicine, Division of Pulmonary and Critical Care, Beth Israel Deaconess Medical Center, Boston, MA. 3Department of Anesthesiology, Aarhus University Hospital, Aarhus, Denmark. 4Department of Medicine, Division of Pulmonary and Critical Care, Baystate Medical Center, MA. 5Department of Medicine, Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, Boston, MA. 6Department of Emergency Medicine, Baystate Medical Center, MA. 7Department of Anesthesia Critical Care, Division of Critical Care, Beth Israel Deaconess Medical Center, Boston, MA.