[1] Johns Hopkins Univ, Sch Med, Dept Pediat Emergency Med, Baltimore, MD 21205 USA
[2] Campbell Univ, Sch Osteopath Med, Lillington, NC USA
[3] Roanoke Mem Hosp, Virginia Tech Carilion Sch Med, Dept Emergency Med, Roanoke, VA USA
[4] Univ Maryland, Sch Med, Dept Emergency Med, Baltimore, MD 21201 USA
[5] Univ Maryland, Sch Med, Charles McC Mathias Natl Study Ctr Trauma & Emerg, Baltimore, MD 21201 USA
[6] Johns Hopkins Sch Med, Dept Emergency Med, Baltimore, MD USA
[7] Maryland Inst Emergency Med Serv Syst, Baltimore, MD 21201 USA
[8] Allegheny Gen Hosp, Dept Emergency Med, Pittsburgh, PA 15212 USA