"Low central venous pressure (low-CVP) or a restrictive fluid administration strategy is usually used worldwide during major liver resection surgery. Although individualized goal directed fluid therapy (GDFT) has been associated with reduced morbidity and mortality in major abdominal surgery, concerns remain on blood loss when applying GDFT in liver surgery. Indeed, GDFT could lead to a higher CVP with the risk of increased blood loss and reduced quality of the surgical field especially during liver dissection.

Since evidence is scarce, this randomized controlled trial investigates the impact of a restrictive vs an individualized GDFT strategy assisted by an assisted fluid management (AFM) system on lactate level, blood loss, and postoperative morbidity including acute kidney injury (AKI) in major liver resections."

Major liver resection surgery is a frequent but complex surgery with high morbidity, even in high activity centers. The morbidity is mainly related to the size of the liver resection and to bleeding, responsible for postoperative hepatocellular failure.

Intraoperative fluid administration is a major component of the anesthetic strategy to optimize the hemodynamic status and peripheral tissue perfusion of the patient. However, high-level evidence recommendations are still lacking regarding the optimal fluid strategy in patients undergoing major liver resection.

On the one hand, it has been accepted for decades that anesthetic management should focus on minimizing intraoperative bleeding by limiting fluid administration. The objective of a ""restrictive"" fluid strategy has often been to maintain a low central venous pressure (CVP), allowing to decrease the venous pressure at the level of the suprahepatic veins and the hepatic section. The lower this pressure, the more limited the bleeding by ""backflow"". This strategy is supported by surgeons because it allows them to maintain a relatively bloodless operating field (by reducing bleeding) and thus facilitates their dissection/surgical work. Under these conditions, however, an infusion of vasopressors is often necessary to maintain adequate perfusion pressure to all organs. In addition, a ""liberal"" fluid administration is often required after liver transection to compensate for blood loss and delayed vascular filling accumulated during most of the surgical procedure. This strategy therefore potentially exposes the patient to the deleterious effects of hypovolemia as reflected by an increase in blood lactate levels. Lactate is considered an indirect marker of the degree of tissue hypoperfusion.

On the other hand, in high-risk abdominal surgery, the anesthesia community recommends a more ""individualized"" fluid strategy, based on the optimization of stroke volume also called ""goal directed fluid therapy"" (GDFT) with the aim of decreasing postoperative complications. It is now even possible to apply this strategy using a real time clinical decision support system (""assisted fluid management"" or AFM). However, the concept of GDFT assisted by AFM (GDFT-AFM) could possibly be accompanied by an increase in CVP and therefore intraoperative bleeding. However, to date, no randomized study has compared these 2 fluid therapy strategies (restrictive vs GDFT-AFM) on lactate level as the primary outcome "

Inclusion Criteria:

• Adult patient
• Major liver surgery

Exclusion Criteria:

-arrythmia -Linguistic barrier -Pregnant women

The Principal investigator, the patient, the surgeon and the outcome assessor will not know the study group allocation