[1] Univ Hosp Tampere, Dept Anaesthesiol & Intens Care, Tampere 33521, Finland
[2] Dist Hosp, Dept Anaesthesiol, Valkeakoski, Finland
[3] Dist Hosp, Dept Anaesthesiol, Vammala, Finland
[4] Dist Hosp, Dept Surg, Valkeakoski, Finland
[5] Univ Tampere, Tampere Sch Publ Hlth, Tampere, Finland
[6] Tampere Univ Hosp, Res Unit, Tampere, Finland
[7] Tampere Univ, Sch Med, FIN-33101 Tampere, Finland