Abstract
BackgroundWe performed an exclusive study to investigate the associations between a total of 23 lactate-related indices during the first 24h in an intensive care unit (ICU) and in-hospital mortality.MethodsNine static and 14 dynamic lactate indices, including changes in lactate concentrations (Δ Lac) and slope (linear regression coefficient), were calculated from individual critically ill patient data extracted from the Multiparameter Intelligent Monitoring for Intensive Care (MIMIC) III database.ResultsData from a total of 781 ICU patients were extracted, consisted of 523 survivors and 258 non-survivors. The in-hospital mortality rate for this cohort was 33.0%. A multivariate logistic regression model identified maximal lactate concentration at 24h after ICU admission (max lactate at T24) as a significant predictor of in-hospital mortality (odds ratio = 1.431, 95% confidence interval [CI] = 1.278–1.604, p<0.001) after adjusting for predefined confounders (age, gender, sepsis, Elixhauser comorbidity score, mechanical ventilation, renal replacement therapy, vasopressors, ICU severity scores). Area under curve (AUC) for max lactate at T24 was larger (AUC = 0.776, 95% CI = 0.740–0.812) than other indices (p<0.001), comparable to an APACHE III score of 0.771. When combining max lactate at T24 with APACHE III, the AUC was increased to 0.815 (95% CI:0.783–0.847). The sensitivity, specificity, and positive and negative predictive values for the cut-off value of 3.05 mmol/L were 64.3%, 77.4%, 58.5%, and 81.5%, respectively.Kaplan-Myer survival curves of the max lactate at T24 for 90-day survival after admission to ICU demonstrated a significant difference according to the cut-off value (p<0.001).ConclusionsThese data indicate that the maximal arterial lactate concentration at T24 is a robust predictor of in-hospital mortality as well as 90-day survival in unselected ICU patients with predictive ability as comparable with APACHE III score.
Highlights
An elevated blood lactate concentration may result from anaerobic metabolism caused by tissue hypoxia, accelerated aerobic glycolysis via the Na-K ATPase due to excess β-adrenergic stimulation, or impaired clearance from liver [1,2]
A multivariate logistic regression model identified maximal lactate concentration at 24h after intensive care unit (ICU) admission as a significant predictor of in-hospital mortality after adjusting for predefined confounders
Area under curve (AUC) for max lactate at T24 was larger (AUC = 0.776, 95% confidence intervals (CI) = 0.740–0.812) than other indices (p
Summary
An elevated blood lactate concentration may result from anaerobic metabolism caused by tissue hypoxia, accelerated aerobic glycolysis via the Na-K ATPase due to excess β-adrenergic stimulation, or impaired clearance from liver [1,2]. Because lactate concentrations are measured with a standard blood gas analyzer, numerous studies have demonstrated that elevated lactate concentrations or lactate changes are strongly associated with patient outcomes [3,4,5,6]. Several lactate indices related to kinetics have been developed and shown to be effective predictors of outcome in diverse cohorts of critically ill patients [5,6]. Changes in lactate concentrations (Δ Lac) have been extensively studied [7,8,9,10,11]. Adequate time intervals or optimal cut-off values for Δ Lac have varied considerably among studies [7,8,9,10,11,12]
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