1 Division of Anaesthetics, Pain Medicine and Intensive Care, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, UK.
2 Department of Anaesthetics, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.
3 Division of Anaesthetics, Pain Medicine and Intensive Care, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, UK. d.antcliffe@imperial.ac.uk.