[1] Univ Liverpool, Dept Clin Psychol, Liverpool L69 3BX, Merseyside, England
[2] Whiston Hosp, Intens Care Unit, Prescot, Merseyside, England
[3] Univ Liverpool, Dept Med, Liverpool L69 3BX, Merseyside, England
[4] Hope Hosp, Intens Care Unit, Salford, Lancs, England
[5] Univ Manchester, Dept Clin Psychol, Manchester, Lancs, England