The first volume optimization of stroke volume (SV) takes place after anaesthesia induction and a stable baseline of measurement is achieved. Note PVI ( mean value during 1 min), MasimoHb, SV (mean value during 1 min) and Flow time corrected (FTC). Data from the oesophagus doppler 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 PVI is >10 % and reduced give a new colloid bolus. For every cycle SV, FTC, MasimoHb and PVI are noted. The first optimization is undertaken before start of surgery.