Evaluation of immediate point‐of‐care test lactate level as a predictor of outcomes in out‐of‐hospital cardiac arrest survivors

Introduction Survival rate of out‐of‐hospital cardiac arrest (OHCA) remained low and admission to intensive care unit (ICU) in Hong Kong was limited by scarce resources. Identifying prognostic markers provided clinicians a valuable assessment to predict patient survival and guide allocation of ICU resources. This study aimed at evaluating the prognostic value of immediate point‐of‐care test (POCT) lactate levels after return of spontaneous circulation (ROSC) in OHCA on 7‐day survival. Methods This was a retrospective single‐center cohort study in a regional hospital from January 2023 to December 2024. All OHCA survivors who were successfully transferred to ward from emergency department (ED) were included. Patients of age under 18, pregnant women, patients achieving ROSC before arrival to ED, and patients without available lactate levels and with incomplete records were excluded. Blood lactate levels were collected immediately after ROSC. Survival at 7 days was taken as the primary endpoint. Results Among 129 OHCA survivors (median age 69), overall 7‐day survival rate was 31.8% ( n = 41). Survivors demonstrated a lower lactate (9.9 vs. 14.9 mmol/L and p < 0.001), lower median age (66 vs. 72 and p = 0.01), presence of shockable rhythms (44% vs. 18% and p = 0.002), and lower rate of prolonged CPR duration more than 20 min (54% vs. 82% and p = 0.001). The predictive values of lactate levels for survival were assessed using a receiver operating characteristic curve. The optimal cutoff value of lactate was 13.6 mmol/L with a sensitivity of 82.9% and specificity of 64.8%. Multivariate logistic regression showed that lactate >13.6 mmol/L (adjusted OR 0.13, 95% CI 0.044–0.385, and p value < 0.001) and increase in age (adjusted OR 0.961, 95% CI 0.926–0.996, and p value 0.03) were independent predictive factors for nonsurvival in 7 days. On the contrary, prolonged CPR duration >20 min did not demonstrate a statistically significant result ( p value = 0.08). Conclusion Immediate lactate levels > 13.6 mmol/L after ROSC is an independent predictor for nonsurvival in 7 days in OHCA survivors.