1 Department of Anesthesiology and Pain Medicine, University of Washington, Harborview Medical Center, Seattle, WA, Department of Neurological Surgery, University of Washington, Seattle, WA Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA Department of Neurological Surgery, University of Washington, Seattle, WA Department of Pediatrics, Seattle Children's Hospital, University of Washington, Seattle, WA Department of Neurological Surgery, University of Washington, Seattle, WA Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Harborview Injury Prevention and Research Center, Department of Anesthesiology and Pain Medicine, Harborview Medical Center, Seattle, WA.