[1] Washington Univ, Sch Med, Div Emergency Med, St Louis, MO 63110 USA
[2] Univ Calif San Francisco, Div Emergency Med, San Francisco, CA 94143 USA
[3] Emory Univ, Div Emergency Med, Atlanta, GA 30322 USA
[4] Carolinas Med Ctr, Dept Emergency Med, Charlotte, NC 28203 USA
[5] VCU, Med Coll Virginia, Dept Emergency Med, Richmond, VA USA