Background: The use of catecholamines for blood pressure and hemodynamic management is essential during undergoing surgery. The type of the catecholamine with the most clinical meaningful effect is still unknown. Therefore, the investigators evaluate the effect of intraoperative continuous infusion of epinephrine, norepinephrine and phenylephrine on intraoperative cardiac output. The investigators further evaluate the effect of epinephrine, norepinephrine and phenylephrine on regional brain and regional tissue oxygenation during surgery.~Methods: The study will include 225 patients ≥ 45 years of age undergoing moderate- to high-risk major open abdominal surgery lasting at least two hours in this prospective double-blinded randomized clinical trial. Patients will be randomly assigned to receive a continuous infusion of epinephrine, norepinephrine or phenylephrine for intraoperative blood pressure management. The primary outcome will be time weighted average (TWA) of cardiac output between continuous infusion of epinephrine, norepinephrine or phenylephrine. The secondary outcomes will be time weighted average of intraoperative brain regional oxygen saturation (brSO2) and tissue regional oxygen saturation (trSO2) between the groups.~Statistics: For the primary outcome, TWA of intraoperative cardiac output between the groups will be analyzed using an ANOVA. The primary outcome, TWA of intraoperative brSO2 and TWA of intraoperative trSO2 will be analysed using an ANOVA.~Level of originality: Data regarding the hemodynamic effects of commonly used intraoperative vasopressors on cardiac output are limited. In detail, effects of different types of catecholamines on hemodynamic parameters and subsequently tissue perfusion in the operative setting are lacking. This study will give further information of the different hemodynamic effects of the most used clinical used catecholamines which are used for intraoperative blood pressure management.
The use of catecholamines for blood pressure and hemodynamic management is essential during undergoing surgery. The type of the catecholamine with the most clinical meaningful effect is still unknown. Therefore, the investigators evaluate the effect of intraoperative continuous infusion of epinephrine, norepinephrine and phenylephrine on intraoperative cardiac output. The investigators further evaluate the effect of epinephrine, norepinephrine and phenylephrine on regional brain and regional tissue oxygenation during surgery.