1. University of Cambridge School of Clinical Medicine , Box 111 Cambridge Biomedical Campus, Cambridge, CB2 0QQ , UK
2. International Health Systems , Department of Engineering & Division of Anaesthesia, , Cambridge , UK
3. University of Cambridge , Department of Engineering & Division of Anaesthesia, , Cambridge , UK
4. Department of Anaesthetics, Cambridge University Hospitals NHS Foundation Trust , Cambridge, CB2 0QQ , UK
5. Division of Anaesthesia, University of Cambridge, Addenbrooke’s Hospital , Hills Road, Cambridge , UK