Individualized Perioperative Hemodynamic Goal-directed Therapy in Major Abdominal Surgery (iPEGASUS-trial)

The trial intervention period will commence from the induction of anesthesia until 8 hours after surgery, or until discharging from the postoperative intensive or intermediate care unit. All patients in the intervention group receive basic vital sign monitoring. For inotropic support dobutamine, and as vasopressor norepinephrine are drugs of choice. Hemodynamic management is performed according to standard treatment until an arterial line is placed. The signal of the arterial line is then processed either by calibrated or non-calibrated pulse contour analysis for pulse pressure variation (PPV) and cardiac index (CI) measurement. Fluid challenge will be performed by infusion of 500 ml in \<15 minute. Choice of fluid in case of indicated fluid loading is determined on basis of the recent guideline for intravasal volume therapy. Patients receive fluids and vasoactive agents following a protocol of individualized parameters regularly achieved by extended hemodynamic monitoring.

Patients in the control group will be treated according to established basic treatment goals (heart rate \<100 bpm, mean arterial pressure \>65 mmHg, SpO2\>94%, and core temperature \>36° C). Basic anesthesiological monitoring by five-lead-electrocardiogram, pulse oximetry, non-invasive blood pressure monitoring and capnography is performed in every patient of the control group. Placement of an arterial and central venous line, as well as fluid and catecholamines administration, are at the discretion of the treating clinician.