1. 1Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts.
2. 2Center for Injury Research and Prevention, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania.
3. 3Center for Injury Research and Prevention, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania.
4. 4Center for Injury Research and Prevention, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania; Division of Emergency Medicine, Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
5. 5Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.