1 Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, Beth Israel Deaconess Medical Center, Boston, MA, United States.
2 Research Center for Emergency Medicine, Aarhus University Hospital, Aarhus, Denmark.
3 Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA, United States.
4 Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, Beth Israel Deaconess Medical Center, Boston, MA, United States; Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA, United States. Electronic address: mdonnino@bidmc.harvard.edu.