Predictors of neurological outcomes after successful extracorporeal cardiopulmonary resuscitation

Background: Extracorporeal cardiopulmonary resuscitation (ECPR) refers to use of extracorporeal membrane oxygenation (ECMO) in cardiopulmonary arrest. Although ECPR can increase survival rates after cardiac arrest, it can also result in poor post-resuscitation neurological status. Thus, we investigated predictors of good neurological outcomes after successful ECPR. Methods: A total of 227 patients underwent ECPR from May 2004 to June 2013 at Samsung Medical Center. Successful ECPR was defined as survival more than 24 hours after ECPR. Neurological outcomes were assessed at discharge using the Glasgow-Pittsburgh Cerebral Performance Categories scale (CPC). CPC 1 and 2 were classified as good and CPC 3 to 5 were classified as poor neurological outcomes. Excluded were 22 patients who did not survive more than 24 hours after ECPR and 90 patients who died from unknown causes or causes other than brain death or whose neurological status could not be assessed at discharge. Multiple logistic regression analysis was used to identify independent predictors of neurological outcomes. Results: Included were 115 patients with a mean age of 58 (range 45-66) years and 80 men (70%). Cardiopulmonary resuscitation (CPR) was performed at non-hospital sites for 19 (17%) patients and bystander CPR was performed in 9 of 19 cases (47%). Cardiac etiology was verified in 74 (64%) patients and therapeutic hypothermia was performed in 9 patients (8%); 68 (59%) had good neurological outcomes and 47 (41%) did not and 24 patients died from brain death. Neurological outcomes were affected by hemoglobin levels before ECMO (P = 0.02), serum lactic acid (P < 0.001) before ECMO insertion, and interval from cardiac arrest to ECMO (P = 0.04). Conclusions: Low hemoglobin or high serum lactic acid levels before ECMO, and prolonged interval from cardiac arrest to ECMO predicted poor neurological outcomes after successful ECPR. Early institution of ECMO and a low threshold for blood transfusion might improve neurological outcomes for patients who survive ECPR.