1 Norwegian National Advisory Unit on Prehospital Emergency Medicine (NAKOS), Oslo University Hospital and University of Oslo, P.O. Box 4956 Nydalen, N-0424 Oslo, Norway; Department of Anaesthesiology, Oslo University Hospital, P.O. Box 4956 Nydalen, N-0424 Oslo, Norway. Electronic address: jo.kramer-johansen@medisin.uio.no.
2 Department of Anaesthesiology, Oslo University Hospital, P.O. Box 4956 Nydalen, N-0424 Oslo, Norway.