1 Safar Center for Resuscitation Research, Department of Critical Care Medicine, University of Pittsburgh; and Children's Hospital of UPMC of Pittsburgh, Pittsburgh, PA Safar Center for Resuscitation Research, Department of Critical Care Medicine, University of Pittsburgh; Children's Hospital of UPMC of Pittsburgh; and Center for Free Radical and Antioxidant Health, Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA.