Establishment Of Asphyxial Cardiac Arrest Model In Rats And Analysis Of Blood Gas Changes In The Early Stage Of Post-resuscitation

Background and purpose Cardiac arrest is a common fatal event worldwide,which has the characteristics of high morbidity,low survival rate and high disability rate.It is estimated that each minute of delay in CPR after cardiac arrest increases mortality by 7%to 10%.Even if the patients survive,there will be varying degrees of neurological impairment,which is the main cause of late death of patients.Due to the process of ischemia,hypoxia and reperfusion after cardiopulmonary resuscitation,patients often have severe acid-base disturbance and electrolyte imbalance.As an important indicator for determining the degree of acid-base imbalance and hypoxia of the body,arterial blood gas analysis is a common detection method during the early stage of cardiopulmonary resuscitation.Arterial blood gas analysis can not only quickly and accurately detect changes of pH,electrolytes and metabolites,but also is helpful for the early diagnosis,effective treatment and long-term prognosis.Therefore,Further research on arterial blood gas analysis in the early stages of CA/CPR has far-reaching significance for the quality of life of survivors.To study brain injury and brain protection after resuscitation,This study provides the rat model of asphyxial cardiac arrest with high operability,high repeatability and stability.And explore the dynamic changes of acid-base imbalance and electrolytes in the early stage of cardiopulmonary resuscitation by analyzing arterial blood gas indexes after CA/CPR in rats.Methods(1)Twenty-five male SD rats were randomly divided into sham operation group(Sham group,n=8)and cardiac arrest cardiopulmonary resuscitation group(CA/CPR group,n=17).Mean artery pressure,the successful rate of cardiopulmonary resuscitation,survival rate and neurological deficit score were recorded at each time point.The rats were sacrificed and the brain tissue were removed for pathological sections at 72h after spontaneous circulation recovery.(2)Seventy-two male SD rats were randomly divided into Sham group and CA/CPR group.The CA/CPR group was further divided into five subgroups,namely 30min group,1h group,2h group,24h-A group and 24h-B group after spontaneous circulation recovery.The femoral arterial blood was collected for blood gas analysis at 30min,1h,2h and 24h after ROSC.Results(1)At 1 minute of resuscitation,MAP in CA/CPR group was significantly lower than that in Sham group(P<0.05).At 3 minutes and 5 minutes of resuscitation,it was significantly higher than that in Sham group(P<0.05).At 10min,15min,20min and 30min of resuscitation,MAP in CA/CPR group was significantly lower than that in Sham group(P<0.05).Compared with the Sham group,the mNSS score of the CA/CPR group was significantly increased at 24h,48h and 72h after the recovery of spontaneous circulation(P<0.05).HE staining of hippocampal tissue sections showed that neuronal cells in CA/CPR group arranged irregularly,distributed unevenly and appeared severely swollen.The pathological changes of neuronal cells were observed,including karyorrhexis,pyknosis and hyperchromatic nuclei.(2)At 30min after the recovery of spontaneous circulation,pH and PaO2 decreased significantly,while PaCO2,Lac,K+ and Glu increased significantly(P<0.05).At lh,2h after the recovery of spontaneous circulation,pH decreased significantly,PaCO2,Lac,K+and Glu increased significantly(P<0.05);At 24h after the recovery of spontaneous circulation,PaO2 was significantly decreased,PaCO2 was significantly increased(P<0.05).Conclusion(1)The rat model of asphyxial cardiac arrest has characteristics of high stability and repeatability,and is suitable for the study of brain injury and brain protection after resuscitation.(2)After spontaneous circulation recovery of the rats,pH,PaO2 were significantly decreased,but PaCO2,Lac,K+and Glu were significantly increased,indicating that there were obvious acidemia,hypoxia,hypercapnia,hyperkalemia and hyperglycemia in the body in the early stage of spontaneous circulation recovery.And it was the most severe within 30 minutes of spontaneous circulation recovery.