pCO2 gap is a surrogate for cardiac output; pCO2 gap = PcvCO2 - PaCO2; pCO2 gap >6 mmHg suggests a persistent shock state that may be amenable to fluid resuscitation +/- intrope support; a “ScvO2-cvaCO2gap-guided protocol” has been proposed to guide the management of septic shock
Resuscitation targets in severe sepsis include: preload, e.g. CVP; afterload, e.g. MAP; tissue oxygen delivery; end point controversial: ScvO2 vs lactate clearance
Central venous oxygen saturation (ScvO2) surrogate for SvO2 thus provides a surrogate measure of oxygen flux, reflecting the balance between oxygen delivery (DO2) and consumption (VO2).
SvO2 vs ScvO2: used as a measure of the adequacy of total body O2 delivery; can be both displayed continuously