1 Division of Critical Care, Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA; Boston MedFlight, Bedford, MA; Division of Neurocritical Care and Emergency Neurology, Departments of Emergency Medicine and Neurology, Yale University School of Medicine, New Haven, CT, and SkyHealth Critical Care, New Haven, CT; Division of Critical Care, Department of Emergency Medicine, Brigham and Women's Hospital, Boston, MA, and Boston MedFlight, Bedford, MA; Brigham and Women's Hospital, Boston, MA, and Boston MedFlight, Bedford, MA.