Effect Of Dopamine With Different Doses On Hemodynamics And Cerebral Oxygen Metabolism In The Early Stage Of Post- Resuscitation In Rabbit With Cardiac Arrest

Background Cardiac Arrest(CA)is the most serious and critical illness in clinical settings.Instantaneous reduction of vital organs such as the brain and heart due to a sudden decrease in blood pressure can cause immediate loss of consciousness,and timely and effective cardiopulmonary resuscitation(CPR)is the key measure to improve the survival rate of CA patients.Dopamine is a commonly used vasoactive drug in clinical practice.It has the function of raising blood pressure and improving the blood supply of important organs such as heart and brain.Dopamine has a significant dose-dependent,low-dose dopamine(2-5μg·kg-1·min-1)mainly activate the peripheral dopamine receptor andβ-receptor,the former effect makes the kidney,mesentery,coronary and Cerebral’s blood vessels relax,the latter effect has a mild to moderate degree of positive inotropic effect on the heart;moderate doses of dopamine(5-10μg·kg-1·min-1)not only significantly agonize theβ1 receptor to stimulate the heart and strengthen systolic force of myocardium,but also exciteαreceptor,making the peripheral blood vessels contract;large doses of dopamine(>10μg·kg-1·min-1)mainly exciteαreceptor andβreceptor,play a role of contraction vascular and positive inotropic effect effect.Early studies confirmed that dopamine for CPR can not only increase the recovery rate of cardiac electric activities,but also increase the rate of return of spontaneous circulation(ROSC),which can improve the systemic and cerebral blood supply after ROSC,and benefit early cerebral resuscitation.However,there is no relevant study on the effect of dopamine dose on the early hemodynamics and cerebral oxygen saturation of CPR.In this experiment,rabbits in the early stage of CPR were treated with different doses of dopamine for elevating the blood pressure.The effects of different doses of dopamine on hemodynamics and cerebral oxygen metabolism in the early stage of CPR were observed.We expext to provide a reference for the selection of dopamine dose in clinical CPR.Objective To observe the effects of dopamine with different doses on hemodynamics and cerebral oxygen metabolism in the early stage of post-resuscitation in rabbit with cardiac arrest.Methods Healthy adult rabbits were randomly divided into 4 groups according to the different doses of dopamine:control group(CG),low dose group(LG),medium dose group(MG),high dose group(HG),n=15 in each group.Ventricular fibrillation(VF)was induced by electricity and cardiopulmonary resuscitation(CPR)was performed subsequently as the protocol.We would stop recruit if the number of return of spontaneous circulation(ROSC)rabbits reached 10 in each group.Cardiac output(CO),mean arterial pressure(MAP),heart rate(HR),systemic vascular resistance index(SVRI)and the cerebral local tissue blood oxygen saturation(TOI)were observed at 0 min,15 min,30 min,60 min,120 min after ROSC.The animals were sacrificed at 120 minutes after ROSC,brain tissues were removed carefully and were analyzed by HE staining.Repeated measures analysis of variance was used to determine the statistical significance among the four groups at different times.Multi-group quantitative data was analyzed by one way anova analysis and then analyze further by LSD test for multiple comparisons.Chi-square test or fisher’s exact probabilities was adopted for multi-group binomial classification variable.Log-rank test was used for comparisons of survival curves in four groups.A two-tailed value of P<0.05 was considered statistically significant.Results There were no differences in the rate of ROSC among groups.Compared with CG and LG,ROSC time was lower in MG(277±15 vs 190±12,P=0.000;252±16 vs 190±12,P=0.016)with higher 120min survival rate(20%vs90%x~2=9.899 P=0.005;30%vs 90%x~2=7.5 P=0.02).CO of MG was higher than other groups at different times in the early stage of post-resuscitation(P<0.05).MAP levels were significantly higher in MG and HG compared with CG and LG at different times after ROSC 15 min(P<0.05).SVRI was significantly higher in HG than other groups at different times after ROSC(P<0.05).Compared with other groups,the TOI levels in MG were significantly higher than the other groups at 15min and 30 min after ROSC(P<0.05).The median survival time in MG and HG were significantly higher than CG and LG.The number of cellular necrosis in MG(28.4±1.0)were significantly lower than other groups(CG:41.2±1.5;LG:41.0±2.0;HG:39.6±1.9)(P<0.01).Conclusion The moderate dose dopamine might maintain MAP and CO at a higher level,which will serve to cerebral oxygen metabolism in the early stage of post-resuscitation from cardiac arrest.