1 Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, One Deaconess Road, Boston, MA 02215, USA. Electronic address: jwjoseph@bidmc.harvard.edu.
2 Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, MGH Emergency Medicine, Founders Building, Suite 852, Boston, MA 02114, USA. Electronic address: bwhite@mgh.harvard.edu.