The Vigileo-FloTrac system High-risk patients Major abdominal surgeries Postoperative Morbidity Mortality a b s t r a c tBackground: This study evaluated impact of intraoperative goal-directed therapy (GDT) judged by changes of stroke volume variation (SVV) and cardiac index (CI) using the Vigileo/FloTrac system on postoperative (PO) morbidities and mortality rates in high risk patients scheduled for major abdominal surgeries in comparison to conventional fluid therapy (CT). Methods: 86 patients were randomly allocated into one of two equal groups: CT group = 43 patients received crystalloid solution and on demand bolus of 250 ml colloids with possible addition of vasopressor or inotrope to target MAP at 60-90 mmHg, CVP at 8-12 mmHg and urine output at >0.5 ml/kg/hr and GDT group = 43 patients received crystalloid fluid therapy (FT) and colloids (3 ml/kg) with possible addition of vasopressor or inotrope according to predefined protocol with a target CI 2.5 L/min/m 2 , SVV < 12% with MAP > 65 mmHg. Physiological and Operative Severity Score for Enumeration of Mortality and Morbidity (POSSUM) was used to predict morbidity and mortality rates. Study outcomes included ICU and total hospital morbidity and mortality rates and length of stay (LOS). Results: Intraoperative GDT reduced ICU morbidity rate (16.3%) than the POSSUM predicted rate (39.78%) and significantly (p = 0.039) than CT group (37.2%), while in CT group ICU morbidity rate coincided with POSSUM predicted rate (42.86%). ICU and total hospital LOS were significantly shorter with GDT group than with CT group. However, mortality rates weren't significantly lower with GDT group than CT group (7% vs. 11.6%). The applied protocol for intraoperative GDT reduced significantly crystalloid infusion and despite of significantly higher amount of received colloids, the total amount of FT was significantly less than CT group. Conclusion: The applied protocol for intraoperative GDT provided significant reduction of PO morbidities, ICU and hospital LOS but couldn't significantly reduce mortality rates in high risk patients scheduled for major abdominal surgeries.