Value of combined lactate and central venous oxygen saturation measurement in patients with sepsis: a retrospective cohort study

. Lactate and central venous oxygen saturation (ScvO 2 ) reflect tissue hypoperfusion but each measure is confounded by many additional factors. These confounding factors differ between lactate and ScvO 2 . Objectives. We postulated that combined assessment of lactate and ScvO 2 may yield information beyond that of each measure alone. Specifically we sought to determine whether lactate has different characteristics and predictive value at different levels of ScvO 2 . Material and methods. We conducted a retrospective analysis of a Derivation cohort and a Validation Cohort of sepsis patients with lactate and ScvO 2 measured within the first 4 hours of intensive care unit admission and 12 hours after resuscitation. Patients were grouped according to: 1) ScvO 2 2 2 > 80 %. Results. Lactate was negatively correlated with ScvO 2 in the ScvO 2 2 in the other ScvO 2 groups. Using receiver operator characteristic analysis in the Derivation Cohort, in the ScvO 2 > 80 % group lactate was predictive of 28-day mortality with an area under the ROC curve (AUC) of 0.94 and an optimal threshold lactate of 3.0 mmol/L. Using this threshold in the ScvO 2 > 80 % groups, 28-day mortality was 32.7 %. Conclusions. Lactate has different characteristics and predictive value at different levels of ScvO 2 . When ScvO 2 2 is consistent with a degree of oxygen supply limitation. When ScvO 2 > 80 % lactate > 3.0 mmol/L is predictive of mortality.