[1] Royal United Hosp, Bath BA1 3NG, Avon, England
[2] Cardiff Univ, Wales Sch Med, Cardiff CF14 4XN, S Glam, Wales
[3] Southampton Gen Hosp, Southampton SO16 6YD, Hants, England
[4] Gloucestershire Hosp NHS Trust, Dept Anaesthet, Gloucester GL1 3NN, England
[5] Calderdale Royal Hosp, Halifax HX3 0PW, England
[6] Resuscitat Council UK, London WC1H 9HR, England
[7] N Bristol NHS Trust, Southmead Hosp, Bristol BS10 5NB, Avon, England