[1] Southampton Gen Hosp, Southampton SO9 4XY, Hants, England
[2] Royal United Hosp, Bath BA1 3NG, Avon, England
[3] Southmead Hosp, Bristol, Avon, England
[4] Univ Oslo, Ulleval Hosp, Surg Intens Care Unit, Oslo, Norway
[5] Univ Amsterdam, Acad Med Ctr, Dept Cardiol, NL-1105 AZ Amsterdam, Netherlands
[6] Univ Warwick, Warwick Med Sch, Warwick, England