[1] Oslo Univ Hosp, Air Ambulance Dept, Prehosp Div, Postbox 4950, N-0424 Oslo, Norway
[2] Norwegian Air Ambulance Fdn, Drobak, Norway
[3] Univ Stavanger, Fac Hlth Sci, Stavanger, Norway
[4] Linkoping Univ, Dept Anaesthesia & Intens Care Med & Hlth, Linkoping, Sweden
[5] Univ Helsinki, Dept Anaesthesiol Intens Care & Pain Med, Helsinki, Finland
[6] Helsinki Univ Hosp, Helsinki, Finland
[7] Landspitali Univ Hosp, Dept Anaesthesia & Intens Care Med, Reykjavik, Iceland
[8] Univ Iceland, Fac Med, Reykjavik, Iceland
[9] Tampere Univ Hosp, Dept Anaesthesia, Tampere, Finland
[10] Univ Tampere, Fac Med & Life Sci, Tampere, Finland
[11] Copenhagen Univ Hosp, Rigshosp, Dept Intens Care, Copenhagen, Denmark
[12] Collaborat Res Intens Care CRIC, Copenhagen, Denmark