Should We Monitor ScVO₂in Critically Ill Patients?

Abstract

Hemodynamic monitoring has become a real challenge in the intensive care unit. As an integrative parameter for oxygen supply/demand, venous oxygen saturation (SvO2) provided by pulmonary artery catheterization is one of the most popular parameters to assess the adequacy of cardiac output. However, technical limitations and potential iatrogenic complications constitute important limits for a widespread use. Regular central venous catheters coupled with a fiberoptic lumen for central venous oxygen saturation (ScvO2) monitoring have been proposed as a surrogate for SvO2 monitoring. The purpose of the present article is to review the physiological backgrounds of circulation, the pathophysiology of circulatory failure and subsequent venous oxygen saturation alterations, and finally the merits and the limits of the use of ScvO2 in different clinical situations.

Oxygen delivery using engineered microparticles

“…All PHMs tested were fluid-filled at the end of the second observation period. To determine whether the release kinetics varied among formulations, we converted the ΔSO 2 to fractional oxygen delivered (SI Calculations, Calculation of Fractional Oxygen Released) (19,28). As expected, the bulk of the O 2 payload was released upon mixing, with ∼85%, 83%, 78%, and 76% of oxygen release occurring within the first minute for formulations 1-4, respectively.…”

“…Briefly, PHMs containing varying amounts of oxygen were added to the reaction vessel containing desaturated donated human blood, and the absolute ΔSO 2 was monitored after a 60-min observation period. The ΔSO 2 was subsequently converted to total volume of O 2 delivered (SI Calculations, Calculation of Oxygen Carrying Capacity of Blood from SO 2 ) (19,28).…”

Nonparametric Method for Estimation of Controlled Correlations in Studies of VEGF-Hypoxia Relationship

“…Oxygen saturation index sO2 and other CO-oximetry parameters in venous blood reflect balance between oxygen delivery and oxygen consumption [9]. Low sO2 correspond to tissue hypoxia [10]. However correlation coefficients between CO-oximetry Figure 1: Correlation between S100 and VEGF levels are compared in groups with sO2 < 38.4% (left scatter plot) and sO2 > 38.4% (right scatter plot).…”

Agreement between Central and Mixed Venous Oxygen Saturation Following Cardiac Surgery

“…In normal individuals, the difference is small between central venous saturation (which represents venous drainage from the upper half of the body) and mixed venous saturation (which represents, in addition, the flow from inferior vena cava and myocardial venous blood) [18]. Consequently, ScvO 2 is usually less than SvO 2 mainly due to high oxygen content in renal venous drainage2, this relationship changes in sick patients with hemodynamic changes, oxygen extraction become higher in renal and splanchnic circulation resulting in reversal of SvO 2 -to-ScvO 2 relationship [19].…”