Anaesthesia: Epidural anaesthesia according to clinical praxis (activated after the first volume optimisation and kept activated during surgery) and anaesthesia according to clinical practise. The ventilation during anaesthesia is maintained using volume controlled mode, tidal volume 7 ml/kg (ideal weight, using the formula: men 50 + 0.91(height in centimetre -152.4); women 45.5 + 0.91(height in centimetre -152.4)), PEEP 5 - 10 cmH2O, respiratory rate to achieve normocapnia. Tidal volume and PEEP is maintained during surgery. The Doppler sond is placed after anaesthesia induction and after that the gastric sond is placed.