Basic infusion: Buffered glucose 2.5% 1000 ml 2 ml/kg/h. The first volume optimization of stroke volume (SV) takes place after anaesthesia induction and a stable baseline of measurement is achieved. Note SV (mean value during 1 min), Flow time corrected (FTC), MasimoHb and PVI (mean value during 1 min). The PVI value is only visualised to the research nurse and not to the attending anaesthesiologist. Administer 3 ml/kg (actual weight) maximum 250 ml hydroxyethyl starch during 5 minutes. Wait for 5 minutes. Note SV, FTC, MasimoHb and PVI. If SV increases more than 10 % a new colloid bolus is given. This is repeated in cycles until SV not increases > 10%, or DO2i > 600 ml/min/m2. For every cycle SV, FTC, MasimoHb and PVI are noted. The first optimization is undertaken before start of surgery.