The prognostic role of lactate in patients who achieved return of spontaneous circulation after cardiac arrest: A systematic review and meta-analysis

Aim: The aim of the study is to conduct a systematic review and meta-analysis of data showing the association of lactate levels with mortality and neurologic outcome in patients who achieved return of spontaneous circulation (ROSC) after cardiac arrest. Methods: An electronic search of PubMed, Embase, Web of Science, and Cochrane Library databases was conducted. Lactate levels at 0, 6, 12, 24, and 48 h after ROSC in survivors versus nonsurvivors and in good versus poor neurologic outcome patients were extracted. Continuous variable and odds ratio were applied for data analysis. Inverse-variance fixed effects model with 95% confidence interval (CI) was used depending on interstudy heterogeneity. Results: A total of 18 articles meeting the study criteria were included for systematic review and 15 for meta-analysis. The results showed that initial serum lactate levels in nonsurvivors were significantly higher than survivors (standardized mean difference [SMD] = −0.43; 95% CI = [−0.52, −0.33]; P < 0.00001), and a higher lactate level at admission was associated with increased hospital mortality. In addition, initial serum lactate levels were significantly higher in poor neurologic outcome patients than good neurologic outcome patients (SMD = −0.44; 95% CI = [−0.54, −0.34]; P < 0.00001), and initial higher lactate level was associated with poor neurologic outcome. There was a statistically significant difference in lactate levels at 6, 12, 24, and 48 h after ROSC, among survivors versus nonsurvivors and among patients presenting good neurologic outcome versus poor neurologic outcome. However, the included studies had small sample size and highly inconsistent data. Conclusions: Higher lactate levels were associated with increased mortality and poor neurologic outcome. Lower lactate levels or faster lactate clearance was associated with higher survival and good neurologic outcome.