Postoperative organ dysfunction severely affects the prognosis of surgical patients. Despite several trials evaluating restrictive or liberal fluid strategies, the ideal fluid replacement strategy remains controversial. Owing to the risk of altered tissue perfusion, a key trigger of organ dysfunction, the purpose of this study was to compare the influence of restrictive and liberal fluid regimens, using a goal-directed approach, on hypovolemia and postoperative organ dysfunction.

Despite several trials evaluating restrictive or liberal fluid strategies, the ideal fluid replacement strategy remains unanswered. Although recent studies suggest that intraoperative fluid restriction may reduce postoperative morbidity and promote faster recovery, extrapolation to individual patients remains difficult. Indeed, whether fluid overload may expose tissue to oedema, impairing oxygenation and wound healing, fluid restriction may, conversely, expose to hypovolemia, which occurs frequently during abdominal surgery, leading to tissue hypoperfusion and organ dysfunction. To date, the restrictive and liberal fluid substitution strategies have not been compared using a goal-directed approach. In addition, recent data suggest that targeting early indicators of hypoperfusion, such as central venous oxygen saturation (ScvO2), which reflects the oxygen delivery/consumption relationship, may be important in the management of patients undergoing major surgery. No data are available on the effects of intraoperative fluid volume replacement strategy on ScvO2 modifications.

The purpose of this study is first to evaluate the influence of restrictive and liberal fluid replacement strategies on both hypovolemia and postoperative organ dysfunction using an oesophageal doppler goal-directed approach (with goal = peak aortic velocity variation and stroke volume optimization) during major abdominal surgery. The second objective is to investigate the effects of fluid loading on ScvO2 modifications.

Inclusion Criteria:

• Major intraabdominal surgery

Exclusion Criteria:

• Age < 18 years
• Pregnancy
• Body mass index > 35 kg/m2
• Emergency surgery
• Coagulopathy
• Sepsis or Systemic inflammatory response syndrome (SIRS)
• Hepatic failure (prothrombin ratio < 50%, factor V < 50%)
• Contraindication for epidural analgesia