The SvO2 study: General design and results of the feasibility phase of a multicenter,randomized trial of three different hemodynamic approaches and two monitoring techniques in the treatment of critically ill patients

Although the attainment of normal hemodynamic values has always been assumed to be the therapeutic target for critically ill patients, recent studies reported increased values in oxygen transport variables in survivors of high-risk surgery. It has been supposed that the higher values observed in survivors might indicate a physiological compensation for the increased metabolic requirements due to disease. We designed a randomized, multicentric trial to evaluate the effect of high values of cardiac index (CI) and oxygen delivery (DO₂) in critically ill patients. Patients enrolled in the study are randomized to three different hemodynamic targets: normal values of CI (2.5 ≤ CI ≤ 3.5 L min⁻¹ m⁻²), supranormal values of CI (CI ≥ 4.5 L min⁻ m⁻²), and mixed venous oxygen saturation (SvO₂) ≥ 70% or (Sat a—Sat v) ≤ 20%. Two different monitoring systems are used to maintain the target: conventional Swan-Ganz catheter with scheduled samples of mixed venous O₂ saturation, and optical catheter with continuous SvO₂ evaluation. The aim of the study is to answer three questions regarding the hypothesis reported above: (1) Are results in postoperative patients applicable to other pathological groups? (2) Does continuous monitoring of SvO₂ provide advantages over conventional hemodynamic monitoring? (3) Is a normal SvO₂ rather than a supranormal CI a good and predictable therapeutic goal? We report herein the protocol of the study and the results of the pilot phase, which was conducted in 98 critically ill patients enrolled by 56 participating centers to evaluate the safety and feasibility of the proposed trial.