[1] Univ Penn, Perelman Sch Med, Dept Emergency Med, Philadelphia, PA 19104 USA
[2] Childrens Hosp Philadelphia, Resuscitat Sci Ctr, Philadelphia, PA 19104 USA
[3] Childrens Hosp Philadelphia, Dept Anesthesiol & Crit Care Med, Philadelphia, PA USA
[4] Univ Penn, Perelman Sch Med, Dept Neurol, Philadelphia, PA USA
[5] Childrens Hosp Philadelphia, Div Neurol, Philadelphia, PA USA
[6] Univ Penn, Dept Chem, Philadelphia, PA USA
[7] Univ Penn, Dept Phys & Astron, Philadelphia, PA USA
[8] Univ Penn, Perelman Sch Med, Dept Pharmacol, Philadelphia, PA USA