Impact of rapid lactate clearance as an indicator of hemodynamic optimization on outcome in out-of-hospital cardiac arrest: A retrospective analysis

OBJECTIVE: We analyzed the impact of rapid lactate clearance as an indicator of hemodynamic optimization on the outcome of out-of-hospital cardiac arrest (OHCA) during early post-cardiac arrest care (PCAC). METHODS: This retrospective analysis was based on a prospective cohort. We selected adult patients with OHCA who achieved a survival event between May 2006 and December 2017. Serum lactate levels were measured at 0 and 6 h after a survival event. The lactate clearance rate was calculated as (lactate at 0 h—lactate at 6 h)/lactate at 0 h. The threshold lactate clearance value for predicting survival to discharge was determined by receiver operating characteristic (ROC) curve analysis. Rapid lactate clearance was defined as the lactate clearance above the threshold value or normalization of serum lactate level (<2.0 mmol/L) at 6 h after a survival event. The primary outcome was survival to discharge. Multivariate logistic regression was used to predict survival to discharge. RESULTS: We enrolled 335 patients. 145 patients (43.3%) survived at discharge. The threshold value of lactate clearance was ≥34% to predict survival to discharge. After adjustment for confounders, the adjusted odds ratios for no hypotension at both 0 and 6 hours and for the presence of rapid lactate clearance for survival to discharge were 8.018 (95% confidence interval [CI] 2.802–22.947) and 2.193 (95% CI 1.263–3.808), respectively. Among patients with early recovery from initial hypotension or with no hypotension events at both 0 and 6 hours, the survival rates were significantly higher in the rapid lactate clearance group than in the non-rapid lactate clearance group. CONCLUSIONS: During the early PCAC period, a rapid decrease in serum lactate level was an indicator of good outcome. Hemodynamic optimization including not only prevention and immediate correction of hypotension but also rapid lactate clearance should be considered in OHCA patients.