[1] Univ Pittsburgh, Sch Med, Dept Crit Care Med, Safar Ctr Resuscitat Res, Pittsburgh, PA USA
[2] Univ Pittsburgh, Sch Med, Dept Epidemiol, Safar Ctr Resuscitat Res, Pittsburgh, PA USA
[3] Univ Pittsburgh, Sch Med, Dept Neurol Surg, Safar Ctr Resuscitat Res, Pittsburgh, PA USA
[4] Univ Pittsburgh, Sch Med, Dept Pediat, Safar Ctr Resuscitat Res, Pittsburgh, PA USA
[5] Childrens Hosp Pittsburgh, Pittsburgh, PA 15213 USA