Lactate and lactate clearance were associated with higher mortality in patients with septic shock

Introduction: An elevated lactate level is associated with higher mortality in patients with severe sepsis. Also, lactate clearance is a surrogate for magnitude and duration of global tissue hypoxia. However, the utility of the lactate clearance after ICU admission as an indicator of outcome in patients with septic shock is still limited. Objectives: The purpose of study is to evaluate the advantage of lactate level and clearance in predicting mortality of patients with septic shock. Methods: We prospectively enrolled 38 patients with septic shock in ICU at Phramongkutklao hospital. Measurements of venous lactate and ScvO2 were obtained at 0, 2, 6, 24, 48, and 72 hours after ICU admission. Lactate clearance was defined as the percent change in lactate levels after 2 or 6 hours from the baseline value. The primary outcome was 28-day mortality rate. Results: The 28-day mortality rate was 55.3%. There was no significant differences in 28-day mortality rate between normal ScvO2 (≥ 70%) group and low ScvO2 (< 70%) group at initial presentation. Using cut off value of 3 mmol/L, higher initial lactate level was significantly associated with higher 28-d mortality (p = 0.017). There was, also, significant association between lactate non-clearance (lactate clearance < 10%) at 2 and 6 hrs and higher 28-d mortality (p = 0.029 and 0.014). Conclusions: Early lactate clearance may indicate a resolution of global tissue hypoxia and is associated with decreased mortality. Patients with higher lactate clearance after 2 and 6 hrs of ICU admission have improved outcome compared with those with lower lactate clearance. Also, initial lactate level was independently associated with 28-day mortality rate.