[1] Boston Childrens Hosp, Div Emergency Med, Boston, MA 02115 USA
[2] Massachusetts Gen Hosp, Div Pediat Emergency Med, Boston, MA 02114 USA
[3] Harvard Med Sch, Dept Pediat, Boston, MA 02115 USA
[4] Univ Massachusetts, Sch Med, Worcester, MA USA
[5] Harvard Med Sch, Dept Emergency Med, Boston, MA 02115 USA