Abstract

BACKGROUND
Serum lactate is a potentially useful biomarker to risk-stratify patients with severe sepsis and septic shock. However, there are only a few studies on the association of serum lactate levels and prognosis in septic shock patients with initial low lactate levels.
METHODS
To evaluate whether initial and follow-up lactate levels associated with mortality in septic shock patients with low lactate level, we conducted a retrospective observational study of patients with septic shock, who were hospitalized through the emergency department in February-July 2008. Initial lactate level was stratified as low (<4 mmol/L) or high (> or =4 mmol/L). The primary outcome was 28-day mortality and multiple logistic regression analysis was used to adjust for potential confounders in the association between lactate clearance and mortality.
RESULTS
Of 90 patients hospitalized with septic shock during the study period, 68 (76%) patients had low initial lactate. Mortality at 28 days was 18% in patients with low lactate level. In these patients, initial lactate level was not associated with mortality (p = 0.590). However, increased lactate at follow-up and lactate clearance were associated with mortality (p = 0.006, p = 0.002, respectively). In a multiple logistic regression analysis, increased mortality rate independently associated with age (OR 1.162, 95% CI 1.041-1.298) and lactate clearance (OR 0.654, 95% CI 0.498-0.859).
CONCLUSIONS
In septic shock patients with a low lactate level, lactate clearance independently associated with a decreased mortality rate. Therefore, lactate clearance could be useful for predicting the outcome in these patients.

• Keywords: lactic acid;mortality;prognosis;septic shock;