[1] Univ Pittsburgh, Sch Med, Dept Pediat, Div Paul C Gaffney Diagnost Referral Serv,Childre, Pittsburgh, PA 15261 USA
[2] Univ Calif San Diego, Dept Pediat, Rady Childrens Hosp San Diego, Div Emergency Med, San Diego, CA 92103 USA
[3] Univ Pittsburgh, Sch Med, Dept Pediat, Pittsburgh, PA 15261 USA
[4] Univ Pittsburgh, Sch Med, Dept Emergency Med, Pittsburgh, PA USA