Serum neuron-specific enolase as an early predictor of outcome after inhospital cardiac arrest

Introduction

Cardiac arrest is a state of severe cerebral perfusion deficit. Patients recovering from a cardiopulmonary resuscitation are at great risk of subsequent death or incapacitating neurologic injury, including a persistent vegetative state. An early definition of neurologic prognosis for these patients has ethic and economic implications.

Objectives

To investigate the prognostic value of serum neuron-specific enolase (NSE) in predicting outcome in patients after a cardiac arrest.

Methods

Forty-five patients resuscitated from inhospital cardiac arrest were prospectively studied from June 2003 to January 2005. Blood samples were collected once in each patient, between 12 and 36 hours after the arrest, for NSE measurements. Outcome was evaluated using the Glasgow Outcome Scale (GOS) 6 months after the event. The Mann–Whitney U test was used to compare patients with unfavourable outcome (Group 1, GOS 1, 2) with patients with favourable outcome (Group 2, GOS 3, 4, 5).

Results

Age and sex were not different between groups. Cardiac causes were responsible for 37.2% of the cardiopulmonary resuscitations. All nonbystander arrests occurred in Group 1. Asystole was the most common arrest rhythm, more frequently seen in Group 1 (P = 0.046). The mean score on the Glasgow Coma Scale was 6.1 ± 3 in Group 1 and 12.1 ± 3 in Group 2 (P < 0.001). The mean time to NSE sampling was 20.2 ± 8.3 in Group 1 and 28.4 ± 8.7 in Group 2 (P = 0.013). Two patients were excluded from analysis because of hemolysis. At 6 months, good outcome was achieved in nine patients (19.6%), 30 patients (69.8%) died and four patients (9.3%) evolved to a persistent vegetative state. The 34 patients (81.4%) with unfavourable outcome (GOS 1, 2) had significantly higher NSE levels than those with a favourable outcome (median NSE 44.24 ng/ml, range 8.1–370 vs 25.26 ng/ml, range 9.28–55.41; P = 0.034).

Conclusion

Outcome after a cardiac arrest is mostly determined by the degree of hypoxic brain damage, and the serum NSE level is a valuable early adjunctive parameter for assessing outcome in these patients.