1. Magill Department of Anaesthesia, Intensive Care and Pain Management, Chelsea & Westminster Hospital, London SW10 9NH, UK
2. Anaesthetic Department, St Michael's Hospital, Southwell Street, Bristol BS2 8EG
3. Department of Anaesthetics, Division of Surgery, Anaesthetics and Intensive Care, Imperial College School of Medicine, Hammersmith Hospital, London W12 0HS
4. Anaesthetic Department, Leicester Royal Infirmary, Leicester LE1 5WW
5. Anaesthetic Department, Northwick Park Hospital, Watford Road, Harrow HA1 3JU, UK