Abstract 269: Relationship Between Characteristics of Early Postresuscitation EEG Activity During Hypothermia and Neurological Outcomes in a Rat Model of Cardiac Arrest

Abstract

Background. Therapeutic hypothermia (HT) improves neurological outcomes and survival after resuscitation from cardiac arrest. However, the effects of HT on early recovery of electroencephalographic (EEG) activity after resuscitation are still unknown. In the current study, we investigated the effect of HT on the characteristics of early post resuscitation EEG activity in a rat model of cardiac arrest. Methods. Twenty male Sprague-Dawley rats (289±28 g) were used in this study. Cardiac arrest was induced through high frequency transesophageal cardiac pacing and untreated for 5 mins. Manual chest compression was initiated at a compression rate of 300/min and continued until return of spontaneous circulation. Immediately after resuscitation, animals were randomized to either 2 hrs hypothermia (N=10) or normothermia (N=10). ECG, EEG, aortic pressure, together with core temperature were continuously recorded. Results. There were no differences in baseline measurements between groups. All the animals were successfully resuscitated, however, 80% of rats survived till 48 hrs in the hypothermia group, in contrast to only 20% in the normothermia one ( p =0.023). Characteristics of EEG activity, including the onset time of EEG bursting (15.1±1.9 min vs. 21.5±6.1 min, p =0.008), and the time of recovery of continuous EEG activity (171.2±15.2 min vs. 242.5±44.0 min, p =0.001) were significantly shorter in the HT group. Both of the onset time of EEG bursting (r=0.66, p =0.002) and the time of recovery of continuous EEG activity (r=0.65, p <0.002) were correlated with good 48 hrs neurological outcomes. Conclusion. The characteristics of early post resuscitation EEG activity during HT were associated with good neurological outcome in this rat model of cardiac arrest. EEG analysis therefore has the potential to monitor neurological recovery and guide HT after resuscitation.