[1] Epsom & St Helier Univ Hosp Trust, Dept Emergency Med, Carshalton, Surrey, England
[2] Heart England NHS Fdn Trust, Heartlands Hosp, Dept Trauma & Orthopaed Surg, Birmingham, W Midlands, England
[3] Ashford & St Peters NHS Fdn Trust, Dept Surg, Chertsey, Surrey, England
[4] Ashford & St Peters NHS Fdn Trust, Dept Anaesthesia, Chertsey, Surrey, England
[5] Charing Cross Hosp, Imperial Coll London, Fac Med, London, England
[6] St Georges Hosp Univ Hosp NHS Fdn Trust, Dept Emergency Med, London, England