Restrictive- vs Individualized Goal Directed Fluid Therapy in Liver Surgery

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 "