[1] Childrens Hosp Philadelphia, Anesthesiol Crit Care Med & Pediat, Philadelphia, PA 19104 USA
[2] Univ Penn, Perelman Sch Med, Philadelphia, PA 19104 USA
[3] Childrens Hosp Philadelphia, Hlth Care Analyt Unit, Philadelphia, PA 19104 USA
[4] Univ Texas Houston, Emergency Med, Houston, TX USA
[5] Childrens Hosp Los Angeles, Rsch Surg, Los Angeles, CA 90027 USA
[6] Univ Southern Calif, Keck Sch Med, Los Angeles, CA 90007 USA
[7] Sky Ridge Med Ctr, Emergency Med, Lone Pine, CO USA
[8] Emory Sch Med, Emergency Med, Atlanta, GA USA