Dynamic lactate indices as predictors of outcome in critically ill patients

Alistair Nichol,Michael Bailey,Craig French,Rinaldo Bellomo,Moritoki Egi,Edward Stachowski,David Cooper,Michael C Reade,Ville Pettila

doi:10.1186/cc10497

Abstract

IntroductionDynamic changes in lactate concentrations in the critically ill may predict patient outcome more accurately than static indices. We aimed to compare the predictive value of dynamic indices of lactatemia in the first 24 hours of intensive care unit (ICU) admission with the value of more commonly used static indices.MethodsThis was a retrospective observational study of a prospectively obtained intensive care database of 5,041 consecutive critically ill patients from four Australian university hospitals. We assessed the relationship between dynamic lactate values collected in the first 24 hours of ICU admission and both ICU and hospital mortality.ResultsWe obtained 36,673 lactate measurements in 5,041 patients in the first 24 hours of ICU admission. Both the time weighted average lactate (LACTW24) and the change in lactate (LACΔ24) over the first 24 hours were independently predictive of hospital mortality with both relationships appearing to be linear in nature. For every one unit increase in LACTW24 and LACΔ24 the risk of hospital death increased by 37% (OR 1.37, 1.29 to 1.45; P < 0.0001) and by 15% (OR 1.15, 1.10 to 1.20; P < 0.0001) respectively. Such dynamic indices, when combined with Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, improved overall outcome prediction (P < 0.0001) achieving almost 90% accuracy. When all lactate measures in the first 24 hours were considered, the combination of LACTW24 and LACΔ24 significantly outperformed (P < 0.0001) static indices of lactate concentration, such as admission lactate, maximum lactate and minimum lactate.ConclusionsIn the first 24 hours following ICU admission, dynamic indices of hyperlactatemia have significant independent predictive value, improve the performance of illness severity score-based outcome predictions and are superior to simple static indices of lactate concentration.

Highlights

Dynamic changes in lactate concentrations in the critically ill may predict patient outcome more accurately than static indices
Static derangements in lactate homeostasis during intensive care unit (ICU) stay have become established as clinically useful markers of increased risk of hospital and ICU mortality [1,3,4,12]
Statement of key findings In a large multi-centre, heterogeneous cohort of critically ill patients, we examined whether dynamic indices of blood lactate concentration over the first 24 hours of ICU admission were independently associated with increased risk of hospital mortality

Summary

Introduction

Dynamic changes in lactate concentrations in the critically ill may predict patient outcome more accurately than static indices. Dynamic indices of lactate homeostasis, which describe magnitude and duration and trend over time, may be even more useful in predicting outcome In support of this hypothesis, a number of small single centre observational studies, principally in patients with severe sepsis and septic shock, have suggested that early changes in blood lactate concentration may be useful in identifying those at high risk of death [5,6,13,14,15,16]. The association between dynamic changes in blood lactate concentration during the first 24 hours of ICU admission and mortality has not yet been investigated in a very large heterogeneous cohort of critically ill patients. To our knowledge no study has compared the ability of dynamic compared to static indices of lactate homeostasis to predict mortality in the critically ill

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