Paired serum S-100B and neuron-specific enolase assay in early and fast assessment of brain damage after cardiac arrest

Background and purpose

Early and accurate predictors of neurological outcome in patients with hypoxic-ischemic encephalopathy after cardiac arrest are needed in order to improve medical decision-making. The aims of the present study were: to assess serum S-100 protein and neuron-specific enolase (NSE) as early markers of brain damage and outcome after cardiac arrest; and to compare the diagnostic and prognostic power of these serum markers to somatosensory evoked potentials (SSEP).

Design

A prospective study. Clinicians were blinded to S-100 and NSE results.

Setting

The ICU of a university hospital.

Methods

Twenty-five patients resuscitated from cardiac arrest (CA) were assessed until they regained consciousness or until death/permanent vegetative state. We correlated SSEP, S-100 protein and NSE serum concentrations with patient outcome. S-100 protein and NSE serum concentrations were measured using an automated chemiluminescent analyzer (Liaison; Diasorin, Saluggia, Italy) in samples collected 24, 48, 72 and 168 hours after the cardiopulmonary resuscitation (CPR); SSEP were recorded at 48 hours and on day 7 after the CPR.

Results

We enrolled 25 consecutive patients (17 males/eight females, mean age 69 ± 17 years, mean APACHE II score 26 ± 4.5); eight of them regained consciousness. Median values of NSE and S-100B serum concentrations were significantly (Mann–Whitney U test) higher in patients who did not regain consciousness compared with patients who regained consciousness at all time intervals (NSE: 53 vs 24 μg/l at 24 hours; 137 vs 20 μg/l at 48 hours; 102 vs 16 μg/l at 72 hours, and 39 vs 6 μg/l 168 hours after CA; S-100B: 2882 vs 342.5 ng/l at 24 hours; 6514 vs 240 ng/l at 48 hours; 3125 vs 198 ng/l at 72 hours, and 610 vs 146 ng/L 168 hours after CA).

S-100B concentration cut-off of 776 ng/l at 24 hours was found the best predictor of not regaining consciousness. The area under the curve was 0.96 (95% confidence interval = 0.88–1.00); specificity was 100%; sensitivity was 82.4%. NSE concentration cut-off point of 45 μg/l at 48 hours was found the best predictor of not regaining consciousness. The area under the curve was 0.87 (95% confidence interval = 0.72–1.00); specificity was 100%; sensitivity was 81.2%.

High association between SSEP responses and outcome was found at 48 hours (rho = 0.68, P < 0.001) and at 7 days (rho = 0.72, P < 0.001) (Spearman correlation).

Conclusions

According to our study and previous reports [1, 2] biochemical markers, and especially S100 protein, provide reliable information about patient outcome after acute global cerebral ischemia. Moreover, we used a recently marketed analyzer that makes available S-100 protein and NSE results within 1 hour; in this way, clinicians can easily and promptly use them in the management of the patient.