Résumé : Replacing mixed venous oxygen saturation (SvO2) monitoring by central venous oxygen saturation (ScvO2) monitoring in order to avoid the use of a pulmonary artery catheter and its related complications is still controversial in the setting of cardiac surgery. The influence of surgery, cardiopulmonary bypass and anaesthesia drugs on the relationship between SvO2 and ScvO2 has never been studied.