1 Division of Neurosurgery, Department of Clinical Neurosciences, and Division of Anaesthesia and Neurosciences Critical Care Unit, Addenbrooke's Hospital, University of Cambridge, Cambridge CB2 0QQ, UK. Electronic address: ak721@cam.ac.uk.
2 Emergency Department, Salford Royal NHS Foundation Trust, Salford, UK; Division of Infection, Immunity and Respiratory Medicine, The University of Manchester, Manchester, UK; The Royal College of Emergency Medicine, London, UK.
3 Division of Neurosurgery, Department of Clinical Neurosciences, and Division of Anaesthesia and Neurosciences Critical Care Unit, Addenbrooke's Hospital, University of Cambridge, Cambridge CB2 0QQ, UK.
4 Imperial Neurotrauma Centre, Department of Surgery & Cancer, Imperial College London, London, UK.