The prognostic performance of lactate in out of hospital cardiac arrest, a post hoc analysis of the TTM-trial

The purpose of this studywas to investigate the prognostic value of lactate at admission, 12-h lactate and 12-h lactate clearance for 30-day survival in comatose patients admitted after out of hospi tal cardiac Arrest (OHCA). Although measures of lactate have been successfully implemented in sepsis and trauma care, most OHCA studies are biased due to design and the results are conflicting. This is a post hoc analysis of the TTM-Trial, a multicentre ran domized controlled trial investigating a temperature intervention of 33 C vs. 36 C after OHCA. 939 patients were analysed. 30-day survival was 56%. Median admission lactate was 6.0mmol/l [3.0-9.5]. Survivors at day 30 had lower admission lactate 4.7mmol/l [2.4-8.9] vs. 7.3mmol/l [4.5-10.7] for non-survivors, p < 0.01. The difference inmedian 12-h lactate was 1.4mmol/l [1.0-2.3] vs. 2.0mmol/l [1.2-3.3], p < 0.01. 12-h lactate clearance was 47±70% in survivors vs. 54±46%, p = 0.03. In a mixed model including all sample times, average lactate valueswere higher in the 33C-group (p < 0.001). In an unad justed model the odds ratio (OR) for death by 1mmol/l increase in lactate was 1.1 [1.1-1.2] at admission (p < 0.01), 1.2 [1.1-1.3] at 12-h (p < 0.01) and 1.003 [1.0-1.01] per % decrease in 12-h clear ance (p = 0.03). In a multivariate analysis, admission lactate and 12-h lactate remained independent predictors of 30-day mortality. A receiver operator curve illustrates the prognostic properties of different measures of lactate in this study. Admission lactate and 12-h lactate are associated with 30-day survival after cardiac arrest. The diagnostic value of these lactate measures is of limited use in clinical praxis.