Optimizing oxygen delivery in the critically Ill: The utility of lactate and central venous oxygen saturation (ScvO₂) as a roadmap of resuscitation in shock

Background Resuscitation of any critically ill patient is aimed at restoration of oxygen delivery to maintain aerobic metabolism. Thus, "endpoints" of resuscitation have been sought after as a measure of evaluating the adequacy of resuscitation. This review article describes the most commonly used endpoints, central venous oxygen saturation (ScvO₂) and lactate, and provides a clinically useful paradigm for utilizing these endpoints during resuscitation of critically ill patients in the emergency department (ED). Objective This review article will summarize the pathophysiology of cellular shock, describe the available research regarding lactate and ScvO₂, and provide an approach to utilizing these endpoints during resuscitation in the ED. Discussion ScvO₂and lactate each have been shown to be useful for the assessment of shock, yet each has inherent limitations. When used together, ScvO₂and lactate provide the emergency physician with a glimpse of the underlying pathophysiologic state, allowing targeted therapy to restore oxygen delivery. Conclusion ScvO₂and lactate are useful endpoints of resuscitation, and when used together, provide a metabolic framework for guiding targeted therapy for critically ill patients in the ED with shock.