Estimated oxygen extraction versus dynamic parameters of fluid-responsiveness for perioperative hemodynamic optimization of patients undergoing non-cardiac surgery: a non-inferiority randomized controlled trial

Background Goal directed therapy (GDT) is able to improve mortality and reduce complications in selected high-risk patients undergoing major surgery. The aim of this study is to compare two different strategies of perioperative hemodynamic optimization: one based on optimization of preload using dynamic parameters of fluid-responsiveness and the other one based on estimated oxygen extraction rate (O 2 ER) as target of hemodynamic manipulation. Methods This is a multicenter randomized controlled trial. Adult patients undergoing elective major open abdominal surgery will be allocated to receive a protocol based on dynamic parameters of fluid-responsiveness or a protocol based on estimated O 2 ER. The hemodynamic optimization will be continued for 6 h postoperatively. The primary outcome is difference in overall postoperative complications rate between the two protocol groups. Fluids administered, fluid balance, utilization of vasoactive drugs, hospital length of stay and mortality at 28 day will also be assessed. Discussion As a predefined target of cardiac output (CO) or oxygen delivery (DO 2 ) seems to be not adequate for every patient, a personalized therapy is likely more appropriate. Following this concept, dynamic parameters of fluid-responsiveness allow to titrate fluid administration aiming CO increase but avoiding fluid overload. This approach has the advantage of personalized fluid therapy, but it does not consider if CO is adequate or not. A protocol based on O 2 ER considers this second important aspect. Although positive effects of perioperative GDT have been clearly demonstrated, currently studies comparing different strategies of hemodynamic optimization are lacking. Trial registration ClinicalTrials.gov, NCT04053595 . Registered on 12/08/2019.