BACKGROUND: Utilization of extracorporeal cardiopulmonary resuscitation with veno-arterial ECMO in patients with cardiac arrest refractory to conventional cardiopulmonary resuscitation has increased in recent years. It is not clear, whether prognostic parameters established in post resuscitation care equally apply to these patients.

METHODS: We retrospectively analyzed a cohort of 103 patients (77.6 % male, mean age 60.8 ± 14.6 years) hospitalized at the medical intensive care unit, University Hospital Jena, between 2004 and 2017 and treated with veno-arterial ECMO placement for cardiac arrest refractory to conventional basic and advanced life support measures.

RESULTS: 89 patients (86.4 %) died, or remained comatose (Cerebral Performance Capacity 4 or 5) within 4 weeks of admission. 14 patients (13.6 %) survived with moderate or minor neurologic deficits (CPC 2 or 3). Mean time on ECMO was 81.5 ± 79.5 hours. Patients with favorable neurologic outcomes (CPC 2 or 3) had significantly shorter low-flow-times between circulatory arrest and ECMO implantation (39.8 ± 45.5 vs. 68.0 ± 41.8 min, p=0.006), showed adequate responses to verbal requests in a wake-up-test performed 48 to 96 hours after cardiac arrest more frequent (86.7 % vs. 30.5 %, p<0.001), and had bilateral cortical primary complexes (N20) in somatosensory evoked potentials of the median nerve. All patients with favorable neurologic outcomes had unremarkable results of cerebral computed tomography scans (100 % vs. 33.3 %, p<0.001). In patients with favorable neurologic outcomes serum levels of neuron-specific enolase (NSE) were significantly lower beyond day 2 and continued to decline, whereas patients with poor outcomes showed increasing NSE levels up to day 3. NSE level showed good discrimination power from day 2 between the two outcome groups (ROC analysis AUC 0.84). Parallelly performed measurements of free hemoglobin showed no significant differences, thus excluding a relevant impact of ECMO induced hemolysis on NSE levels.

CONCLUSIONS: Early assessment of neurologic outcome of patients on veno-arterial ECMO after cardiopulmonary resuscitation is feasible by means of the established prognostic parameters NSE, SSEPs, CCT and neurologic examination.