[1] Univ Warwick, Warwick Med Sch, Warwick Clin Trials Unit, Coventry CV4 7AL, W Midlands, England
[2] Univ Hosp Birmingham, Birmingham, W Midlands, England
[3] Univ Hosp Schleswig Holstein, Inst Emergency Med, Kiel, Germany
[4] Maggiore Hosp, Dept Anaesthesia, Intens Care & Emergency Med Serv, Bologna, Italy
[5] Univ Oslo, Dept Anesthesiol, Oslo Univ Hosp, Oslo, Norway
[6] Univ Oslo, Inst Clin Med, Oslo, Norway
[7] North Bristol NHS Trust, Southmead Hosp, Bristol, Avon, England
[8] Johannes Gutenberg Univ Mainz, Univ Med Ctr, Dept Anesthesiol, Mainz, Germany
[9] Univ Ghent, Fac Med, Dept Emergency Med, Ghent, Belgium
[10] EMS Dispatch Ctr, Fed Dept Hlth, Ghent, Belgium
[11] Univ Hosp Plymouth, Dept Neonatol, Plymouth, Devon, England
[12] Thames Valley Air Ambulance, Stokenchurch, England
[13] Natl & Kapodistrian Univ Athens, Med Sch, Athens, Greece
[14] Univ Antwerp, Antwerp, Belgium
[15] Univ Bern, Bern Univ Hosp, Dept Anaesthesiol & Pain Med, Bern, Switzerland
[16] Sigmund Freud Univ Vienna, Sch Med, Vienna, Austria
[17] Antwerp Univ Hosp, Dept Emergency Med, Antwerp, Belgium
[18] Akureyri Hosp, Akureyri, Iceland
[19] Univ Akureyri, Akureyri, Iceland
[20] Royal United Hosp, Bath, Avon, England