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

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 2 ) levels, in patients after cardiopulmonary resuscitation (CPR). 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 2 ). Preliminary findings were externally validated in a database containing over 2,000 patients from multiple intensive care units (eICU database). Admission pH levels predicted in-hospital mortality (area-under-curve 0.75, p