[1] Univ Penn, Perelman Sch Med, Dept Pediat, Philadelphia, PA 19104 USA
[2] Childrens Hosp Philadelphia, Dept Pediat, Div Pediat Emergency Med, Philadelphia, PA USA
[3] Univ Penn, Dept Anesthesia & Crit Care, Sch Med, Philadelphia, PA 19104 USA
[4] Childrens Hosp Philadelphia, Dept Anesthesia & Crit Care, Philadelphia, PA 19104 USA
[5] Childrens Hosp Philadelphia, Dept Biomed & Hlth Informat, Philadelphia, PA 19104 USA
[6] Northwestern Univ, Dept Pediat, Feinberg Sch Med, Chicago, IL 60611 USA
[7] Ann & Robert H Lurie Childrens Hosp Chicago, Dept Pediat, Div Pediat Emergency Med, Chicago, IL USA