1. Registrar, School of Postgraduate Studies, Morriston Hospital, Swansea SA6 6NL, UK,
2. Consultant, Department of Anaesthesia, School of Postgraduate Studies, Morriston Hospital, Swansea SA6 6NL, UK,
3. Clinical Research Scientist, School of Postgraduate Studies, Morriston Hospital, Swansea SA6 6NL, UK,
4. Department of Anaesthesiology, Kansai Medical University, 10–15 Fumizono‐cho, Moriguchi City, Osaka, 570, Japan