1 School of Engineering, University of Warwick, Coventry, CV4 7AL, UK.
2 Anaesthesia and Critical Care, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, NG7 2UH, UK.
3 Department of Anaesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA. yehyan@email.chop.edu.
4 School of Engineering, University of Warwick, Coventry, CV4 7AL, UK. D.Bates@warwick.ac.uk.