[1] Royal Surrey Cty Hosp NHS Fdn Trust, Dept Anaesthesia, Guildford GU2 7XX, Surrey, England
[2] Royal Surrey Cty Hosp NHS Fdn Trust, Dept Hepatobiliary Surg, Guildford GU2 7XX, Surrey, England
[3] Univ Surrey, Fac Hlth & Med Sci, Guildford GU2 5XH, Surrey, England