In operating theater, one of the bigger purpose of anesthetist-resuscitator is to optimize vascular filling (VF) because of a failure or an excess of filling is deleterious for the patient. Several studies have assessed the traditionnal VF based on the clinic and the VF guided by quantitative critereas. Thus studies have showed a decrease of morbidity and duration of patients' stay whose the VF was guided even on the long term. So, formal recommandations of experts (FRE) on the perioperative filling strategy of the SFAR ( Anesthesia and Resuscitation Francophone Society) advise to titrate the perioperative vascular filling of high risk patients guiding on a mesure of end-systolic volume (ESV). The inscrease of ESV answering to filling confirmed the VF realized is relevant and authorized its pursuite while the absence of an increase of the ESV after a filling test signifies the useless and deleterious character of this one. The optimization of perioperative hemodynamics consists in adapting the patient's cardiac output to his metabolic needs. ETO, Swan-Ganz: limit of its application to the routine. The central venous oxygen saturation (ScvO2) is simple and safe, the evaluation of the adjustment of O2 inputs compared to the needs. The industry has developed continuous monitoring systems by reflection spectrophotometry using optical fibers installed in the central venous pathways. In daily practice, the stricto sensu application of FRE leads to administering an VF up to the limit of the preload dependence without evaluating the adequacy of the cardiac output, which is not a physiological situation. This filling is therefore sometimes performed solely on the criteria of preload dependence while it is potentially deleterious for the patient. No study has compared a strategy based on the use of ScvO2 and preload dependence with current recommendations based solely on preload dependence. Our hypothesis is that the continuous monitoring of the ScvO2 in the superior cave territory in intraoperative would allow to detect the patients with an inadequacy of the cardiac output and thus to select the only ones requiring a vascular filling. This would reduce postoperative complications related to overfilling, without exposing the patient to episodes of tissue hypoperfusion.

Inclusion Criteria:

• >50 years old
• ASA score ≥ 2
• requiring a major intra-abdominal scheduled surgery
• lasting more than 90 min
• in the visceral surgery, vascular surgery, urological surgery and gynecological surgery sectors

Exclusion Criteria:

• <18 years old
• Pregnant or brest feeding patients
• no consentement
• Unstable acute pathology at the time of surgery (acute heart, respiratory or renal failure, severe sepsis or septic shock, hemorrhagic shock);
• rhythm disorders type ACFA early intervention;
• Palliative surgery, ASA 5;
• Patient under guardianship or curatorship.