Comparison Of Brain Injuries In Rat Cardiac Arrest Models Induced By Asphyxia And Electrical Stimulation

Objective To compare the severity of brain injury between asphyxia and electrical stimulation induced cardiac arrest in rats.Methods Forty-two healthy male SD rats were randomized into sham group(n=6),asphyxia group(n=18)and electrical stimulation group(n=18).Rats in asphyxia group were subjected to tracheal tube clamping while rats in electrical stimulation group were subjected to trans-esophageal electrical stimulation,cardiopulmonary resuscitation(CPR)was performed 4minutes after CA.CA was not induced in the sham group.Animals were allowed to survive up to 72 hours.The neurological deficit scores(NDS)were measured at 24 h and 72 h post resuscitation,neuronal damage in hippocampal CA1 region were detected by HE staining,and brain injury related bio-markers(NSE and S100B)were measured by ELISA.Results Cardiac arrest was successfully induced in both the asphyxia group and the trans-esophageal electrical stimulation group.94.4%(17/18)and 88.9%(16/18)animals were resuscitated successfully in the two groups respectively.The 72-hour survival rate was similar in the asphyxia group and the electrical stimulation group(70.59% vs 75%,p=0.84).Both groups had higher NDS than sham group in 24 h after resuscitation(24h:37.5±4.26,32.17±4.02 vs 8.33±2.33,p<0.01),however,there was no difference between the asphyxia group and the electrical stimulation group(p=0.317).At 72 h after resuscitation,NDS in asphyxia group was higher than that in the electrical stimulation group(p<0.05)and sham group.HE staining showed there was no significant neuronal damage in the two groups at 24 h after resuscitation.At 72 h after resuscitation,more obvious damage was observed in the asphyxia group than the electrical stimulation group.The levels of NSE in the asphyxia and electrical stimulation groups were higher than those in the sham group(ng/ml:1.02±0.07,1.02±0.02 vs 0.87 ±0.02,p<0.05).The level of NSE in the asphyxia group 72 h after resuscitation remained slightly than the sham groupi(ng/ml:1.03±0.05 vs 0.87±0.02,p<0.01),while it had recovered to normal level in the electrical stimulation group.There was no significant difference in S100 B levels at neither groups nor time points post resuscitation.Conclusion In this experiment,both cardiac arrest models induced by asphyxia and electrical stimulation show a certain degeree of brain injuries.Brain injuries are more severe in asphyxia-induced cardiac arrest compared to electrical stimulation induced cardiac arrest.