Improved Early Postresuscitation EEG Activity for Animals Treated with Hypothermia Predicted 96 hr Neurological Outcome and Survival in a Rat Model of Cardiac Arrest

Bihua Chen,Feng-Qing Song,Ling-Yan Lei,Meng-Hua Chen,Yongqin Li,Lei-Lei Sun,Wei-Ni Gan

doi:10.1155/2013/312137

Abstract

Purpose. To investigate the effect of hypothermia on 96 hr neurological outcome and survival by quantitatively characterizing early postresuscitation EEG in a rat model of cardiac arrest. Materials and Methods. In twenty male Sprague-Dawley rats, cardiac arrest was induced through high frequency transesophageal cardiac pacing. Cardiopulmonary resuscitation was initiated after 5 mins untreated arrest. Immediately after resuscitation, animals were randomized to either 2 hrs of hypothermia (N = 10) or normothermia (N = 10). EEG, ECG, aortic pressure, and core temperature were continuously recorded for 6 hrs. Neurological outcome was evaluated daily during the 96 hrs postresuscitation period. Results. No differences in the baseline measurements and resuscitation outcome were observed between groups. However, 96 hr neurological deficit score (204 ± 255 versus 500 ± 0, P = 0.005) and survival (6/10 versus 0/10, P = 0.011) were significantly better in the hypothermic group. Quantitative analysis of early postresuscitation EEG revealed that burst frequency and spectrum entropy were greatly improved in the hypothermic group and correlated with 96 hr neurological outcome and survival. Conclusion. The improved burst frequency during burst suppression period and preserved spectrum entropy after restoration of continuous background EEG activity for animals treated with hypothermia predicted favorable neurological outcome and survival in this rat model of cardiac arrest.

Highlights

Out-of-hospital cardiac arrest (CA) is a major public health problem all over the world
We investigated the effect of mild hypothermia on EEG recovery, as well as the relationship between characteristics of early postresuscitation EEG activities and 96 hr neurological outcome and survival in a rat model of CA
The cardiac rhythm rapidly deteriorated from ventricular fibrillation (VF) to pulseless electrical activity (PEA) before cardiopulmonary resuscitation (CPR) was initiated

Summary

Introduction

Out-of-hospital cardiac arrest (CA) is a major public health problem all over the world. Despite efforts to improve outcomes from CA, the overall survival is less than 10% among patients successfully resuscitated [4, 5]. The greatest postresuscitation emphasis has mainly been on preserving neurologic function [8]. Among all postresuscitation care suggested and/or recommended, therapeutic hypothermia (TH) is the most persuasive intervention that can significantly improve neurologic recovery and survival after resuscitation from CA [9, 10]. Prediction of outcome may be, an important aspect to be considered during the postresuscitation care in order to avoid the likelihood of unnecessary prolongation of TH when a good functional recovery has already been achieved or to avoid unjustified withdrawal of care if the protection has not been fully achieved yet. Neurological examination and electrophysiological studies have guided physicians in predicting

Methods

Results

Conclusion