Cumulative lactate and hospital mortality in ICU patients
1 Department of Anaesthesiology, University Medical Center Groningen, University of Groningen, PO Box 30001, Groningen 9700 RB, the Netherlands
2 Department of Intensive Care Medicine, Medical Center Leeuwarden, PO Box 888, Leeuwarden, 8901 BR, the Netherlands
3 Department of Intensive Care Medicine, Gelre Hospitals, location Lucas, PO Box 9014, Apeldoorn, 7300 DS, the Netherlands
4 Department of Anesthesia and Intensive Care Medicine, Luzerner Kantonsspital, Luzern, 6000, Switzerland
5 HERMES Critical Care Group, Amsterdam, The Netherlands
Annals of Intensive Care 2013, 3:6 doi:10.1186/2110-5820-3-6Published: 27 February 2013
Both hyperlactatemia and persistence of hyperlactatemia have been associated with bad outcome. We compared lactate and lactate-derived variables in outcome prediction.
Retrospective observational study. Case records from 2,251 consecutive intensive care unit (ICU) patients admitted between 2001 and 2007 were analyzed. Baseline characteristics, all lactate measurements, and in-hospital mortality were recorded. The time integral of arterial blood lactate levels above the upper normal threshold of 2.2 mmol/L (lactate-time-integral), maximum lactate (max-lactate), and time-to-first-normalization were calculated. Survivors and nonsurvivors were compared and receiver operating characteristic (ROC) analysis were applied.
A total of 20,755 lactate measurements were analyzed. Data are srpehown as median [interquartile range]. In nonsurvivors (n = 405) lactate-time-integral (192 [0–1881] min·mmol/L) and time-to-first normalization (44.0 [0–427] min) were higher than in hospital survivors (n = 1846; 0 [0–134] min·mmol/L and 0 [0–75] min, respectively; all p < 0.001). Normalization of lactate <6 hours after ICU admission revealed better survival compared with normalization of lactate >6 hours (mortality 16.6% vs. 24.4%; p < 0.001). AUC of ROC curves to predict in-hospital mortality was the largest for max-lactate, whereas it was not different among all other lactate derived variables (all p > 0.05). The area under the ROC curves for admission lactate and lactate-time-integral was not different (p = 0.36).
Hyperlactatemia is associated with in-hospital mortality in a heterogeneous ICU population. In our patients, lactate peak values predicted in-hospital mortality equally well as lactate-time-integral of arterial blood lactate levels above the upper normal threshold.