| Objective: To investigate whether dexmedetomidine has a protective effect on heart,brain,lung,liver,kidney during the cardiopulmonary resuscitation(CPR)and after recovery in the New Zealand rabbit model of CPR.Methods: Twenty-seven healthy adult male New Zealand rabbits were randomly divided into three groups: control group(group C,n=nine),median dose dexmedetomidine group(group M,n=nine)and high dose dexmedetomidine group(group H,n=nine).All animals were anesthetized,inserted trachea cannula by tracheotomy for mechanical ventilation,femoral artery was punctured and placed catheter for arterial blood pressure monitoring,the thoracic cavity was opened to expose the heart.Thirty minutes after the operations were completed,intravenous injected four degrees Celsius potassium chloride(4℃,70 mg/kg)to induce cardiac arrest,three minutes later,began to cardiopulmonary resuscitation(Intracardiac compression).At the same time,the control group was given the same volume of fluid equal to the other two groups of dexmedetomidine(1ml/kg/h)in the beginning of resuscitation.The median dose group was given dexmedetomidine(saline 38 ml + dexmedetomidine 200 ug 2ml,total 40 ml,5ug/ml)5ug(1ml)/kg/h,the high dose group was given dexmedetomidine(saline 18ml+ dexmedetomidine 200 ug 2ml,total 20 ml,10ug/ml)10ug(1ml)/kg/h.If it fails to recover after fifteen minutes of CPR,then give up.After the Restoration of spontaneous circulation,(ROSC),continued to observe the rabbits until they were died or survived for 12 hours,recorded the heart rate,arterial blood pressure,mean arterial pressure;examined the arterial blood gas analysis before the cardiac arrest,immediately,and the 1、3 hour after ROSC;detected the blood creatinine,alanine aminotransferase,aspartate aminotransferase,total bilirubin,CK-MB,troponin I,interleukin-1,tumor necrosis factor –a before cardiac arrest and the 3、6 、12 hour after ROSC,and recorded the total amount of urine.12 hours later,the rabbits were systemic perfused with formaldehyde,and the heart,brain,lung,kidney and liver tissue were removed for paraffin sections to observe the pathological changes by H-E staining,to detect the apoptosis situation using Tunel method(Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling).Results: 1.The success rate of recovery,recovery time,defibrillation frequency,dose of adrenalin,survival time,pH,PCO2,PO2,GLU,K+,ALT,AST,TB,SBP,DBP and MAP show no significant difference(P > 0.05);2.Compared with the control group,HCO3-,BE,LAC,CRE,CK-MB,CTnI,urine volume,IL-1,TNF-a are significant difference in the median dose dexmedetomidine group(P < 0.05).There are no significant difference between the high dose group and the control group,also the high dose group and median dose group(P > 0.05).The heart rate between High dose group and median dose group,high dose group and control group are significant difference(P < 0.05).3.The results of pathological show that the pathological damage of each organ in median dose group are the lightest.4.Tunel test shows that the apoptosis of each organ in the median dose group compared with the control group and high dose group,is significantly reduced,the high dose group and the control group had no significant difference Conclusion: 1.It can duplicate the rabbit cardiac arrest model successfully to intravenous injection the high dose potassium.2.Middle dose dexmedetomidine can alleviate the pathological damage of important organs after cardiopulmonary resuscitation and inhibit apoptosis,and has obvious protective effect on heart and kidney function.3.High doses of dexmedetomidine,due to its impact of the circulation,weaken or offset the protection on the organs.4.Dexmedetomidine may protect the important organs by improving the aerobic metabolism,inhibiting the inflammation,restraining the apoptosis and so on. |
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