[1] Yale Univ, Sch Med, Dept Emergency Med, New Haven, CT 06510 USA
[2] Harvard Med Sch, Beth Israel Deaconess Med Ctr, Dept Emergency Med, Boston, MA 02115 USA
[3] Johns Hopkins Sch Med, Dept Emergency Med, Baltimore, MD USA
[4] Yale Univ, Sch Med, New Haven, CT USA
[5] Yale Coll, New Haven, CT USA
[6] Univ Calif San Francisco, Dept Pediat Emergency Med, San Francisco, CA 94143 USA
[7] Univ Washington, Sch Med, Dept Emergency Med, Seattle, WA USA