Ability of neuron-specific enolase to predict survival to hospital discharge after successful cardiopulmonary resuscitation

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Abstract
Background: Accurate prediction of survival to hospital discharge in patients who achieve return of spontaneous circulation after cardiopulmonary resuscitation (CPR) has significant ethical and socioeconomic implications. We investigated the prognostic performance of serum neuron-specific enolase (NSE), a biochemical marker of ischemic brain injury, after successful CPR. Methods: In-hospital or out-of-hospital patients with nontraumatic normothermic cardiac arrest who achieved return of spontaneous circulation (ROSC) following at least 5 minutes of CPR were eligible. Neuron-specific enolase levels were assessed immediately, 6 hours, 12 hours and 2 days after ROSC. Subjects were followed to death or hospital discharge. Results: Seventeen patients (7 men, 10 women) were enrolled during a 1-year period. Median (range) NSE levels in survivors and non-survivors respectively were as follows: immediately after ROSC: 14.0 μg/L (9.1–51.4 μg/L) versus 25.9 μg/L (10.2–57.5 μg/L); 6 hours after ROSC: 15.2 μg/L (9.7–30.8 μg/L) versus 25.6 μg/L (12.7–38.2 μg/L); 12 hours after ROSC: 14.0 μg/L (8.6–32.4 μg/L) versus 28.5 μg/L (11.0–50.7 μg/L); and 48 hours after ROSC: 13.1 μg/L (7.8–29.5 μg/L) versus 52.0 μg/L (29.1–254.0 μg/L). Non-survivors had significantly higher NSE levels 48 hours after ROSC than surivors (p = 0.04) and showed a trend toward higher values during the entire time course following ROSC. An NSE concentration of >30 μg/L 48 hours after ROSC predicted death with a high specificity (100%: 95% confidence interval [CI] 85%–100%), and a level of 29 μg/L or less at 48 hours predicted survival with a high specificity (100%: 95% CI 83%–100%). Conclusions: Serum NSE levels may have clinical utility for the prediction of survival to hospital discharge in patients after ROSC following CPR over 5 minutes in duration. This study is small, and our results are limited by wide confidence intervals. Further research on ability of NSE to facilitate prediction and clinical decision-making after cardiac arrest is warranted.