1. P. Armstrong, FCAnaes, Research Fellow, Department of Anaesthesia, Edinburgh University, Royal Infirmary Edinburgh, Lauriston Place, Edinburgh EH3 9YW.
2. J. Watters, MB, ChB, Senior House Officer, Department of Anaesthesia, Edinburgh University, Royal Infirmary Edinburgh, Lauriston Place, Edinburgh EH3 9YW.
3. A. Whitfield, FFARCS, Consultant, Department of Anaesthesia, Edinburgh University, Royal Infirmary Edinburgh, Lauriston Place, Edinburgh EH3 9YW.