[1] Brown Univ, Alpert Med Sch, Dept Emergency Med, Div Pediat Emergency Med, Providence, RI 02912 USA
[2] Univ Texas Austin, Dell Med Sch, Dell Childrens Med Ctr Cent Texas, Dept Pediat, Austin, TX 78712 USA
[3] George Washington Univ, Sch Med & Hlth Sci, Div Emergency Med, Washington, DC 20052 USA
[4] Maimonides Hosp, Dept Emergency Med, Div Pediat Emergency Med, Brooklyn, NY 11219 USA
[5] Columbia Univ, Vagelos Coll Phys & Surg, Dept Emergency Med, Div Pediat Emergency Med, New York, NY USA
[6] Univ Toronto, Dept Pediat, Div Emergency Med, Toronto, ON, Canada
[7] Brown Univ, Warren Alpert Sch Med, Dept Emergency Med, Providence, RI 02912 USA
[8] Injury Prevent Ctr, Providence, RI USA
[9] Univ Ottawa, Dept Pediat & Emergency Med, Ottawa, ON, Canada