Serum lactate poorly predicts central venous oxygen saturation in critically ill patients: a retrospective cohort study

Serum lactate and central venous oxygen saturation (ScvO ) are commonly used and commonly recommended as markers of tissue oxygenation in shock states. Medical literature has both explicitly stated and implied that the two biomarkers are interchangeable in the management of patients with shock. However, there have been relatively few direct comparisons of these tests in clinical circumstances, and the relationship between them is uncertain. The objective of our study was to evaluate whether simultaneous or near-simultaneous measurements of lactate and ScvO reveal a consistent relationship between these two biomarkers. A retrospective cohort study was conducted in an urban, academic US hospital. All adults in ICUs between March 2007 and March 2017 who had a lactate measurement and ScvO or mixed venous oxygen saturation (SvO ) measurement made +/- 1 h from the lactate were included. Linear and non-linear correlations of ScvO and lactate were assessed in a variety of shock states. Two thousand sixty-two patients were included. Lactate and ScvO correlated poorly ( = 0.0041, = 0.0019). This was true for patients with ScvO ≤ 65% ( = 0.0431,