Résumé : BACKGROUND: Goal-directed fluid therapy (GDFT) has been associated with improved patient outcomes. However, implementation of GDFT protocols remains low despite growing published evidence and the recommendations of multiple regulatory bodies in Europe. We developed a closed-loop-assisted GDFT management system linked to a pulse contour monitor to assist anaesthesiologists in applying GDFT. OBJECTIVE: To assess the impact of our closed-loop system in patients undergoing major abdominal surgery in an academic hospital without a GDFT programme. DESIGN: A case-control study with propensity matching. SETTING: Operating rooms, Erasme Hospital, Brussels. PATIENTS: All patients who underwent elective open major abdominal surgery between January 2013 and December 2016. INTERVENTION: Implementation of our closed-loop-assisted GDFT in April 2015. METHODS: A total of 104 patients managed with closed-loop-assisted GDFT were paired with a historical cohort of 104 consecutive non-GDFT patients. The historical control group consisted of patients treated before the implementation of the closed-loop-system, and who did not receive GDFT. In the closed-loop group, the system delivered a baseline crystalloid infusion of 3 ml kg h and additional 100 ml fluid boluses of either a crystalloid or colloid for haemodynamic optimisation. MAIN OUTCOME MEASURES: The primary outcome was intra-operative net fluid balance. Secondary outcomes were composite major postoperative complications, composite minor postoperative complications and hospital length of stay (LOS). RESULTS: Baseline characteristics were similar in both groups. Patients in the closed-loop group had a lower net intra-operative fluid balance compared with the historical group (median interquartile range [IQR] 2.9 [1.6 to 4.4] vs. 6.2 [4.0 to 8.3] ml kg h; P < 0.001). Incidences of major and minor postoperative complications were lower (17 vs. 32%, P = 0.015 and 31 vs. 45%, P = 0.032, respectively) and hospital LOS shorter [median (IQR) 10 (6 to 15) vs. 12 (9 to 18) days, P = 0.022] in the closed-loop group. CONCLUSION: Implementation of our closed-loop-assisted GDFT strategy resulted in a reduction in intra-operative net fluid balance, which was associated with reduced postoperative complications and shorter hospital LOS. TRIAL REGISTRATION NUMBER: NCT02978430.