Abstract 12070: Post-Cardiac Arrest Sedation Modulates Electroencephalographic Slow-Wave Activity and Promotes Neurological Recovery in a Mouse Model of Cardiac Arrest

Abstract

Introduction: The majority of patients resuscitated from cardiac arrest (CA) present in coma or with an altered level of consciousness. Although CA survivors are routinely sedated during targeted temperature management, the effects of sedation on CA outcomes remain to be determined. Hypothesis: Post-CA sedation would modulate cerebral physiology and improve neurological outcomes in mice. Methods: Adult C57BL/6J mice of both sexes were subjected to potassium chloride-induced CA and thereafter resuscitated with manual chest compression. Starting at return of spontaneous circulation (ROSC) or at 60 minutes after ROSC, mice received intravenous infusion of propofol at 40 mg · kg -1 · h -1 , dexmedetomidine at 1 μg · kg -1 · h -1 , or normal saline for 2 hours. Body temperature was lowered and maintained at 33°C during sedation. Cerebral blood flow was measured for 4 hours after ROSC. Telemetric electroencephalogram (EEG) was recorded in freely moving mice from 3 days before up to 7 days after CA. Results: Sedation with propofol or dexmedetomidine starting at ROSC attenuated brain injury and improved survival in hypothermia-treated post-CA mice (propofol [13/16] vs. no sedation [4/16], P = 0.008; dexmedetomidine [14/16] vs. no sedation [4/16], P = 0.002). Mice that were not sedated after ROSC exhibited cerebral hyperemia immediately after resuscitation and EEG power in all frequency bands remained less than 20% of the baseline in the first 4 hours after ROSC. Administration of propofol or dexmedetomidine starting at ROSC attenuated cerebral hyperemia and induced slow-wave (0.5-4 Hz) EEG activity that reached near baseline levels during and early after sedation. Increased EEG activity within 6 hours after ROSC was associated with improvement in neurological outcomes at 24 hours post-CA. In contrast, delayed sedation starting at 60 minutes after ROSC failed to improve outcomes, without attenuating cerebral hyperemia and inducing slow-wave EEG activity. Conclusions: Post-CA sedation with propofol or dexmedetomidine improved neurological outcomes and survival in mice resuscitated from CA and treated with hypothermia. The beneficial effects of sedation were accompanied by attenuation of the cerebral hyperemic response and induction of EEG slow-wave activity.