Marco Bo Hansen1, Anne Møller Nielsen2. 1. Emergency Medical Services, Copenhagen, University of Copenhagen, Denmark. Electronic address: marcobhansen@gmail.com. 2. Emergency Medical Services, Copenhagen, University of Copenhagen, Denmark; Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark.