[1] Univ Utah, Dept Pediat, Div Pediat Emergency Med, Salt Lake City, UT USA
[2] Univ Penn, Childrens Hosp Philadelphia, Dept Pediat, Philadelphia, PA 19104 USA
[3] Univ Utah, Dept Pediat, Div Pediat Crit Care, Salt Lake City, UT USA
[4] Univ Toronto, Dept Pediat, Toronto, ON, Canada
[5] Univ Toronto, Dept Pharmacol & Toxicol, Toronto, ON, Canada
[6] Univ Cincinnati, Dept Pediat, Div Emergency Med, Cincinnati, OH USA
[7] Univ Colorado, Dept Pediat, Denver, CO 80202 USA
[8] Childrens Natl Hlth Syst, Div Emergency Med, Washington, DC USA
[9] Northwestern Univ, Dept Pediat, Ann & Robert H Lurie Childrens Hosp Chicago, Feinberg Sch Med, Chicago, IL 60611 USA