Serum neuron-specific enolase as a prognostic marker for irreversible brain damage in comatose cardiac arrest survivors

Objective: To assess the use of serum neuron-specific enolase (S-NSE) level as a noninvasive predictor of CNS injury irreversibility in comatose cardiac arrest survivors. Methods: An observational, prospective clinical study was performed in a community hospital ED and intensive care unit, All cardiac arrest survivors (n = 52) with impaired neurologic status admitted between February 1994 and May 1995 were followed until return of consciousness (1) or death due to CNS failure (0). Serum samples for S-NSE determination (ng/mL) using the radioimmunoassay technique were obtained 24 hours after cardiac arrest. Data were analyzed using stepwise logistic regression with dichotomized predictors to validate the correlation between S-NSE (X) and outcome (Y), where X = 0 if less than or equal to median and 1 if > median S-NSE level. Adjustment was made for the following variables: glucose level on admission, total epinephrine dose used before return of spontaneous circulation, and best Glasgow Coma Scale score on admission. These data were all available in 34 cases. In 16 cases, CSF enzymes at 48 hours postarrest were obtained and compared with S-NSE. Results: The logistic equation determining the influence of S-NSE (X) on outcome (Y) was: Y = 0.606 - 1.785X (odds ratio = 6; p = 0.020). There was no confounding effect of the other variables related to survival. The mean S-NSE value for all the patients was 34 (7.9-188). All the patients recovering consciousness (n = 15) had an S-NSE mean +/- SEM value of 17.5 +/- 2.4, with a maximum of 47. Conclusion: These data support the conclusion that measurement of S-NSE at 24 hours post-cardiac arrest may supplement clinical assessment of hypoxic-ischemic encephalopathy after cardiac arrest.