[1] Univ Penn, Childrens Hosp Philadelphia, Dept Anesthesiol & Crit Care, Div Crit Care Med,Perelman Sch Med, Philadelphia, PA 19104 USA
[2] Univ Penn, Childrens Hosp Philadelphia, Dept Pediat, Div Emergency Med,Perelman Sch Med, Philadelphia, PA 19104 USA
[3] Georgetown Univ, McCourt Sch Publ Policy, Washington, DC USA
[4] Georgetown Univ, Dept Govt, Washington, DC USA
[5] Northwestern Univ, Dept Pediat, Lurie Childrens Hosp Chicago, Div Emergency Med,Feinberg Sch Med, Chicago, IL 60611 USA
[6] Childrens Hosp Philadelphia, Dept Biomed & Hlth Informat, Philadelphia, PA 19104 USA
[7] Univ Penn, Childrens Hosp Philadelphia, Dept Pediat, Perelman Sch Med, Philadelphia, PA 19104 USA
[8] Penn State Univ, Coll Med, Penn State Hershey Childrens Hosp, Div Pediat Crit Care Med, Hershey, PA USA