1 Department of Anesthesiology and Critical Care Medicine, Children's Hospital Los Angeles, Los Angeles, CA, and Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA; Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA; Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, and Southern California Clinical and Translational Science Institute, Biostatistics Core, Los Angeles, CA; Department of Anesthesiology and Critical Care Medicine, Children's Hospital Los Angeles, Los Angeles, CA, and Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA.