1. University College London Hospitals, National Hospital for Neurology & Neurosurgery 1 Neurocritical Care Unit , , London WC1N 3BG , UK
2. University of Queensland 2 Princess Alexandra Hospital Southside Clinical Unit , , Brisbane QLD 4102 , Australia
3. University College London 3 Department of Medical Physics and Biomedical Engineering , , Malet Place Engineering Building, London WC1E 6BT , UK
4. School of Sport, Rehabilitation and Exercise Sciences, University of Essex 4 , Wivenhoe Park, Colchester CO4 3SQ , UK