Tissue oxygenation parameters to guide fluid therapy: OXYGEN-DERIVED PARAMETERS AND FLUID THERAPY

SUMMARY Because tissue hypoxia is a key trigger for organ dysfunction, adequacy of oxygen delivery (DO2) to tissue oxygen metabolic demand is essential during the perioperative period. Optimization of DO2, using either or both fluid loading and inotropic support, to prevent tissue hypoxia in relation to increased oxygen consumption (VO2), could improve outcome. In this context, the use of central venous oxygen saturation (ScvO2), which reflects important changes in the DO2/VO2 relationship and of central venous-to-arterial carbon dioxide difference [P(cv-a)CO2], to address adequacy of oxygen utilization, has shown promising results. The threshold value for ScvO2 at which the risk of impaired tissue oxygenation can be discarded might remain out of reach and the complementary use of P(cv-a)CO2 would provide help to adjust the right DO2 to both VO2 and CO2 production. When applying this dual view, and increasing cardiac output to lower P(cv-a)CO2 below 6 mmHg, the adapted ScvO2 is closer to 73% or 75%.