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

Abstract

Background Serum lactate and central venous oxygen saturation (ScvO 2 ) 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 2 reveal a consistent relationship between these two biomarkers. Methods 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 2 or mixed venous oxygen saturation (SvO 2 ) measurement made +/− 1 h from the lactate were included. Linear and non-linear correlations of ScvO 2 and lactate were assessed in a variety of shock states. Results Two thousand sixty-two patients were included. Lactate and ScvO 2 correlated poorly ( r 2 = 0.0041, p = 0.0019). This was true for patients with ScvO 2 ≤ 65% ( r 2 = 0.0431, p < 0.001), patients with normal kidney and liver function ( r 2 = 0.0517, p < 0.001), and septic shock patients ( r 2 = 0.0037, p = 0.17). For patients with an O 2 extraction ratio ≥ 50%, lactate and ScvO 2 were strongly correlated ( r 2 = 0.93, p = 0.0019), but these patients represented only 2.8% of patients in whom the ratio could be calculated. Conclusions Lactate can predict ScvO 2 when patients are at or below the critical oxygen delivery threshold, but relatively few shock patients meet this criterion. In the overall population of critically ill patients, serum lactate predicts ScvO 2 poorly, even after controlling for factors that may affect lactate production. Lactate and ScvO 2 should not be assumed to be interchangeable markers of tissue oxygenation/perfusion. Electronic supplementary material The online version of this article (10.1186/s40560-019-0401-5) contains supplementary material, which is available to authorized users.

Appropriate Clinical Use of Lactate Measurements

“…49 In a study of more than 2,000 patients, lactate and mixed venous oxygen saturation from a central vein had poor correlation for patients with mixed venous oxygen saturation from a central vein less than or equal to 65%, normal kidney and liver function, and septic shock. 50 Similarly, for 79% of patients, there was no relationship between lactate clearance and mixed venous oxygen saturation from a central vein using mixed venous oxygen saturation from a central vein greater than or equal to 70% in the first 6 h of resuscitation. 51 When peripheral perfusion-targeted resuscitation was compared to changes in lactate, there was no difference in mortality seen.…”

Risk and Prognostic Factors of Replantation Failure in Patients With Severe Traumatic Major Limb Mutilation: a Retrospective Cohort Study

“…Lactic acid may be helpful in predicting levels of oxygen debt accumulation and resuscitation needs, and its measurement may serve as a predictor of high-risk trauma [24]. Central venous oxygen saturation as another indicator of tissue oxygenation may be valuable for predicting the prognosis of large limb replantation [25]. Lactic acid and albumin levels were found to be good predictors of replantation failure in this study.…”

Individualized Hemodynamic Management in Sepsis

“…One single-center retrospective cohort study examined the relationship between lactate and ScvO 2 and found that lactate had very little predictive ability for ScvO 2 in the vast majority of critically ill patients; therefore, lactate should not be used interchangeably with ScvO 2 as a marker of tissue hypoxia [ 28 ]. This is not surprising if we take into account that lactate is only considered pathological when it is high, while ScvO 2 reflects abnormality both when low and when elevated.…”