1 ST6 Anaesthesia and Perioperative Medicine Fellow, Department of Anaesthesia and Critical Care, University College London Hospitals NHS Foundation Trust, London W1G 8PH.
2 POPS Clinical Fellow, Department of Geriatrics, Guys and St Thomas' Hospital, London.
3 ST2 Cardiothoracic Surgery, Department of Cardiothoracic Surgery, University Hospital of South Manchester NHS Foundation Trust, Manchester.