Early Quantitative Gamma-Band EEG Marker is Associated with Outcomes After Cardiac Arrest and Targeted Temperature Management

Abstract

Background Brain recovery after cardiac arrest (CA) is sensitive to temperature. Yet the effect of temperature management on different EEG frequency bands has not been elucidated. A novel quantitative EEG algorithm, sub-band information quantity (SIQ), was applied to evaluate EEG recovery and outcomes after CA. Methods 24 Wistar rats undergoing 7-min CA were randomly assigned to immediate hypothermia (32–34°C), normothermia (36.5–37.5°C), or hyperthermia (38.5–39.5°C) (N=8). EEG was recorded continuously for the first 8 hrs and then for serial 30-min epochs daily. The Neurologic Deficit score (NDS) at 72-hr was the primary functional outcome. Another 4 rats without brain injury were added as a control. Results Better recovery of gamma-band SIQ was found in the hypothermia group (0.60±0.03) compared with the normothermia group (0.40±0.03) (p<0.01) and in the normothermia group compared with the hyperthermia group (0.34±0.03) (p<0.05). The NDS was also improved in the lower temperature groups: hypothermia [median (25th, 75th), 74 (61, 74)] versus normothermia [49 (47, 61)] versus hyperthermia [43 (0, 50)] (p<0.01). Throughout the 72-hr experiment, the gamma-band SIQ showed the strongest correlation at every time point (ranging 0.520–0.788 from 30-min to 72-hr post-resuscitation, all p<0.05) whereas the delta-band SIQ had poor correlation with the 72-hr NDS. No significant difference of subband EEG was found with temperature manipulation alone. Conclusions Recovery of gamma-band SIQ-qEEG was strongly associated with functional outcomes after CA. Induced hypothermia was associated with faster recovery of gamma-band SIQ and improved functional outcomes. Targeted temperature management primarily affected gamma frequency oscillations but not delta rhythm.

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Neuroprotection of Glibenclamide against Brain Injury after Cardiac Arrest via Modulation of NLRP3 Inflammasome

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