[1] Virginia Commonwealth Univ, Sch Med, Dept Emergency Med, Richmond, VA 23284 USA
[2] Vanderbilt Univ, Med Ctr, Vanderbilt Inst Clin & Translat Res, Nashville, TN USA
[3] Vanderbilt Univ, Med Ctr, Dept Emergency Med, Nashville, TN USA
[4] Vanderbilt Univ, Med Ctr, Dept Med, Nashville, TN USA