Goal directed fluid management in major abdominal surgery has been shown to reduce perioperative complications. The approach aims to optimize the intravascular fluid volume by use of minimally invasive devices which calculate flow-directed variables such as stroke volume (SV) and stroke volume variation (SVV). The investigators aim to show the feasibility of routinely implementing such hemodynamic monitoring during major abdominal surgery, and to evaluate its effects in terms of perioperative fluid management and postoperative outcomes.