[1] Lapland Cent Hosp, Dept Anaesthesia & Intens Care, Rovaniemi 96101, Finland
[2] Helsinki Univ Cent Hosp, Div Anaesthesia & Intens Care Med, Intens Care Units, Helsinki, Finland
[3] Univ Helsinki, Dept Clin Sci, FIN-00014 Helsinki, Finland
[4] Monash Univ, ANZIC RC, Dept Epidemiol & Prevent Med, Melbourne, Vic 3004, Australia
[5] South Karelia Cent Hosp, Dept Anaesthesia & Intens Care Med, Lappeenranta, Finland
[6] Turku Univ Hosp, Dept Anaesthesia & Intens Care Med, FIN-20520 Turku, Finland
[7] Cent Finland Cent Hosp, Dept Anaesthesia & Intens Care Med, Jyvaskyla, Finland
[8] Middle Ostrobothnia Cent Hosp, Dept Anaesthesia & Intens Care Med, Kokkola, Finland
[9] N Karelia Cent Hosp, Dept Intens Care, Joensuu, Finland
[10] Satakunta Cent Hosp, Dept Anaesthesia & Intens Care Med, Pori, Finland
[11] Tampere Univ Hosp, Dept Intens Care Med, Tampere, Finland