Acidemia predicts mortality independently of lactate levels in patients after cardiac arrest.

Aim: We examined whether post-cardiac arrest acidemia is associated with 30-day mortality and neurological outcomes among hospital survivors, independent of lactate and partial arterial carbon dioxide pressure (paCO Methods: The predictive value of acidemia for in-hospital mortality was analyzed retrospectively in 742 non-traumatic cardiac arrest patients admitted to a German high-volume tertiary center using receiver operating characteristic (ROC) analysis. Patients were stratified using the ROC-derived (Youden-optimal) pH cut-off, and 30-day mortality was compared across strata. Cox regression assessed the association between severe acidemia (pH ≤ 7.2, binary) and mortality and examined its consistency across prespecified subgroups (age, sex, cardiac arrest type, lactate, and paCO Results: Admission pH levels predicted in-hospital mortality (area-under-curve 0.75, Conclusion: Post-cardiac-arrest acidemia is associated with higher mortality independently of lactate, ventilation, or CPR characteristics. Among hospital survivors, admission pH was not significantly associated with neurological outcome. These findings support pH as an early marker for mortality risk stratification after cardiac arrest, to be interpreted in the context of multimodal prognostication.