1. Department of Surgery, South Manchester University Hospitals Trust, Nell Lane, West Didsbury, Manchester M20 8LR, UK,
2. Department of Haematology, South Manchester University Hospitals Trust, Nell Lane, West Didsbury, Manchester M20 8LR, UK,
3. Department of Anaesthetics, South Manchester University Hospitals Trust, Nell Lane, West Didsbury, Manchester M20 8LR, UK