Utilisation de la SvO 2

Abstract

Monitoring of O 2 venous saturation (SvO 2) is easily performed with fiberoptic pulmonary artery catheters and is used in circulatory shock to assess global balance between tissue O 2 supply and O 2 demand (VO 2). Simultaneous measurement of SvO 2 and continuous Cardiac Output (CO), as recently allowed by modified artery catheters, improve SvO 2 interpretation. Indeed, a decrease in SvO 2 may result from a decrease in arterial O 2 saturation, a decrease in hemoglobin or CO or from an increase in VO 2. SvO 2 is a surrogate marker of tissue O 2 extraction (EO 2) with SvO 2 = 1 – EO 2. When EO 2 is altered, as observed in septic shock, SvO 2 does not anymore guarantee correct interpretation of tissue oxygenation. Central venous O 2 saturation (ScvO 2) can be monitored with more easiness and a lower risk than mixed venous O 2 saturation with a good correlation between SvO 2 and ScvO 2. ScvO 2 has been recently used for early goal-directed therapy in patients with severe sepsis in order to improve hemodynamics at the emergency room; this was associated with a 16% reduction ( p = 0.009) in in-hospital mortality.