1 School of Health Sciences, City University of London, London, UK.
2 National Centre of Research Excellence in Nursing, Menzies Health Institute Queensland, Griffith University, Intensive Care Unit, Princess Alexandra Hospital, Nathan, Australia.
3 School of Nursing and Health Sciences, University of Dundee, Dundee, UK.
4 Department of Psychiatry, University of Dundee, Dundee DD1 9SY, UK.