[1] Kings Coll Hosp NHS Fdn Trust, Dept Crit Care, London, England
[2] North West London Sch Anaesthesia, Pan London Sch Intens Care Med, London, England
[3] Oxford Univ Hosp NHS Fdn Trust, Dept Crit Care, Oxford, England
[4] Kings Coll Hosp NHS Fdn Trust, Dept Cardiol, London, England
[5] Royal Papworth Hosp NHS Fdn Trust, Dept Crit Care, Cambridge, England