1. Division of Anaesthesia, Department of Medicine, University of Cambridge, Cambridge, United Kingdom, South-East Scotland School of Anaesthesia, Edinburgh, United Kingdom
2. Division of Asthma, Allergy and Lung Biology, King’s College London, London, United Kingdom, Department of Critical Care, Guy’s & St. Thomas’s Hospitals, London, United Kingdom
3. Critical Care Unit, Royal Papworth Hospital, Cambridge, United Kingdom