1. 1Swedish Air Ambulance (Svensk Luftambulans), Mora, Sweden.
2. 2Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts; Harvard Medical School, Boston, Massachusetts.
3. 3Department of Anesthesiology and Pain Medicine, The Ottawa Hospital Civic Campus, University of Ottawa, Ottawa, Canada.
4. 4Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts; Harvard Medical School, Boston, Massachusetts.