[1] Yeovil Dist Hosp, Dept Res & Dev, Yeovil, Somerset, England
[2] Yeovil Dist Hosp, Dept Surg, Yeovil, Somerset, England
[3] Derriford Hosp, Dept Accid & Emergency, Plymouth PL6 8DH, Devon, England
[4] E London NHS Trust, Mile End Hosp, Dept Gen Adult Psychiat, London, England
[5] Univ Hosp Leicester, Dept Anaesthet, Leicester, Leics, England
[6] Musgrove Pk Hosp, Res Design Serv, Taunton, Somerset, England
[7] St Marks Hosp, Dept Surg, London EC1V 2PS, England