[1] Univ Cambridge, Sch Clin Med, Cambridge CB2 1TN, England
[2] Cambridge Univ Hosp NHS Fdn Trust, Cambridge Breast Unit, Cambridge CB2 2QQ, England
[3] Cambridge Univ Hosp NHS Fdn Trust, Dept Anaesthesia, Cambridge CB2 2QQ, England
[4] Cambridge Univ Hosp NHS Fdn Trust, ICU, Cambridge CB2 2QQ, England
[5] Cambridge Univ Hosp NHS Fdn Trust, Plast & Reconstruct Surg Depatment, Cambridge CB2 2QQ, England
[6] Anglia Ruskin Univ, Postgrad Med Inst, Cambridge, Chelmsford, England