Alpha-power in electroencephalography as good outcome predictor for out-of-hospital cardiac arrest survivors

Abstract

This study aimed to investigate the utility of quantitative EEG biomarkers for predicting good neurologic outcomes in OHCA survivors treated with targeted temperature management (TTM) using power spectral density (PSD), event-related spectral perturbation (ERSP), and spectral entropy (SE). This observational registry-based study was conducted at a tertiary care hospital in Korea using data of adult nontraumatic comatose OHCA survivors who underwent standard EEG and treated with TTM between 2010 and 2018. Good neurological outcome at 1 month (Cerebral Performance Category scores 1 and 2) was the primary outcome. The linear mixed model analysis was performed for PSD, ESRP, and SE values of all and each frequency band. Thirteen of the 54 comatose OHCA survivors with TTM and EEG were excluded due to poor EEG quality or periodic/rhythmic pattern, and EEG data of 41 patients were used for analysis. The median time to EEG was 21 h, and the rate of the good neurologic outcome at 1 month was 52.5%. The good neurologic outcome group was significantly younger and showed higher PSD and ERSP and lower SE features for each frequency than the poor outcome group. After age adjustment, only the alpha-PSD was significantly higher in the good neurologic outcome group (1.13 ± 1.11 vs. 0.09 ± 0.09, p = 0.031) and had best performance with 0.903 of the area under the curve for predicting good neurologic outcome. Alpha-PSD best predicts good neurologic outcome in OHCA survivors and is an early biomarker for prognostication. Larger studies are needed to conclusively confirm these findings.

Figure 1

Representative visual analysis of raw data. The visual analysis could not differentiate poor and good neurological outcome. Example of EEGs from patients with poor (left panel) and good (right panel) neurological outcomes. Top—EEG filtered with a 0.5-Hz high-pass filter with a sensitivity of 10 μV/mm. Middle—EEG filtered with a 14-Hz high-pass filter with a sensitivity of 5 μV/mm. Bottom—EEG filtered with a 30-Hz high-pass filter with a sensitivity of 5 μV/mm. The alpha-PSD values of this epoch in patients with poor (left panel) and good (right panel) neurologic outcomes were 0.06 and 3.07, respectively.

Figure 2

Scattered dots of (A) PSD, (B) ERSP, and (C) SEs of all and each frequency. Small star, p < 0.05; Large start, age-adjusted p < 0.05 by linear mixed model.

Figure 3

ROC curve (blue line) and predictive values according to the cutoff of alpha-PSDs; under the curve (AUC) of 0.903 and p value < 0.001.