Hyperlactatemia in ICU patients: Incidence, causes and associated mortality

Abstract

Purpose To describe the incidence, causes and associated mortality of hyperlactatemia in critically ill patients and to evaluate the association between lactate clearance and in-hospital survival. Methods Retrospective cohort study of patients with hyperlactatemia admitted to the ICU. Hyperlactatemia was defined as a blood lactate concentration ≥ 5 mmol/L and high-grade hyperlactatemia a lactate level ≥ 10 mmol/L. Lactate clearance was calculated as the percentage of decrease in lactate concentration from the peak value. Results Of 10,123 patients, 1373 (13.6%) had lactate concentration ≥ 5 mmol/L, and 434 (31.6%) of them had ≥ 10 mmol/L. The most common causes of hyperlactatemia were sepsis/septic shock and post-cardiac surgery. An association was found between lactate concentration and in-hospital mortality (p < 0.001). The area under the receiver-operating-characteristics (ROC) of lactate concentration and the optimal cut off to predict mortality were 0.72 (0.70–0.75) and 8.6 mmol/L, respectively. ROC analysis for lactate clearance to predict in-hospital survival showed that the best area under the curve was obtained at 12 h: 0.67 (95% confidence interval 0.59–0.75). Conclusions Hyperlactatemia was common and associated with a high mortality in critically ill patients. Lactate clearance had limited utility for predicting in-hospital survival.