Does lactate measurement performed on admission predict clinical outcome on the intensive care unit? A concise systematic review

Background There is a need for practical, efficient and effective prognostic markers for patients admitted to the intensive care unit (ICU) with sepsis, to identify patients at highest risk and guide and monitor treatment. Although many biomarkers and scoring systems have been advocated, none have yet achieved this elusive combination. Most ICUs already use blood lactate concentrations to monitor patients but the evidence base for this application is unclear. Methods A systematic review of the last five years of evidence of effectiveness of lactate measurement in prediction of outcome in ICUs was performed. Results It was found that there is a lack of high-quality evidence, and no specific studies of prognostic accuracy. d- or l-Lactate concentrations measured in plasma, serum, whole blood or colonic washings were raised at admission in almost all patient groups, and were higher in patient groups who had the worst outcomes (in-hospital mortality, sequential organ failure). However, there was significant overlap in individual concentrations measured in those who died within 28 days of admission, or who developed multiple organ failure, and those who did not. For serum l-lactate concentrations, no specific cut-off value capable of predicting in-hospital mortality or sequential organ failure could be recommended. Conclusions The evidence reviewed suggested that whole blood, plasma or serum lactate measurement could not provide specific prognostic information for individual patients. There may be a role for monitoring for normalization of serum d- or l-lactate concentrations during goal-directed therapy in the ICU but further good-quality studies are needed. Measurement of the d-lactate stereoisomer shows promise, such that further studies are warranted.