1 Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA; Department of Anesthesiology, Aarhus University Hospital, Aarhus, Denmark. Electronic address: lwandersen@clin.au.dk.
2 Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA; Department of Medicine, Division of Pulmonary and Critical Care, Beth Israel Deaconess Medical Center, MA, USA.