Central venous oxygen saturation in septic shock--a marker of cardiac output, microvascular shunting and/or dysoxia?

Shock therapy aims at increasing central venous oxygen saturation (ScvO2), which is a marker of inadequate oxygen delivery. In this issue of Critical Care, Textoris and colleagues challenge this notion by reporting that high levels of ScvO2 are associated with mortality in patients with septic shock. This is of obvious interest, but as their retrospective design has inherent limitations, the association should be confirmed in a prospective, multicenter study with protocolized ScvO2 measurements and detailed registration of potentially confounding factors.