Comparing clinical only and combined clinical laboratory models for ECPR outcomes in refractory cardiac arrest

Extracorporeal cardiopulmonary resuscitation (ECPR) improves survival for prolonged cardiac arrest (CA) but carries significant risks and costs due to ECMO. Previous predictive models have been complex, incorporating both clinical data and parameters obtained after CPR or ECMO initiation. This study aims to compare a simpler clinical-only model with a model that includes both clinical and pre-ECMO laboratory parameters, to refine patient selection and improve ECPR outcomes. Medical records between January 2012 and January 2019 in our institution were retrospectively reviewed. Patients who met the following criteria were enrolled in the ECPR program: age 18-75 years, CCPR started with CA in < 5 min, CA was assumed to be of heart origin, and refractory CA. Survivors had similar underlying diseases and younger age without statistical significance (57.0 vs. 61.0 years, p = 0.117). Survivors had significantly higher rates of initial shockable rhythm, pulseless ventricular tachycardia and ventricular fibrillation, shorter low-flow time (CPR-to-ECMO time), lower lactate levels, and higher initial pH. Survival to discharge was higher for emergency department CA than for out-of-hospital and in-hospital CA (63.3% vs. 35.3%, p = 0.007). Two models were used for evaluating survival to discharge and good neurological outcomes. Model 1, short version based on clinical factors, (S1, survival score 1; F1, function score 1) included the patient's characteristics before ECPR, whereas Model 2, full version included clinical factors and laboratory data including lactate and pH levels (S2, survival score 2; F2, function score 2). Both Model 1(S1) and Model 2(S2) showed good predictive ability for survival to discharge with areas under the receiver operating characteristic (AUROCs) of 0.79 and 0.83, respectively. Model 1(F1) and Model 2(F2) revealed prediction power for good neurological outcomes, with AUROCs of 0.80 and 0.79, respectively. The AUROCs of survival score Model 1(S1) and 2(S2) and function score Model 1(F1) and 2(F2) were not significantly different. This study demonstrates that clinical factors alone can effectively predict survival to discharge and favorable neurological outcomes at 6 months. This emphasizes the importance of early prognostic evaluation and supports the use of clinical data as a practical tool for clinicians in decision-making for this difficult situation.