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