Hemodynamic instability is frequent during surgery and intraoperative hypotension is associated with excess morbidity and excess mortality in high-risk patients. In major abdominal surgery the incidence of intraoperative hypotension remains high. For the past few years, some teams have proposed evaluating norepinephrine as a first-line drug in the presence of hypotension or even before hypotension occurs Thus in obstetrics, the preventive use of norepinephrine for cesareans performed under spinal anesthesia was associated with a reduction in the incidence of hypotension per operative without deleterious effect for the newborn or parturient. In the absence of any observed complications, several teams began to use noradrenaline prophylactically in other surgery. However, no study has demonstrated its benefit, particularly the term of surgical complication in abdominal surgery. The objective of this work is to assess the preventive use of norepinephrine in major abdominal surgery on the occurrence of intraoperative hypotension, postoperative organ dysfunction and postoperative medical and surgical complications.