Effects Of Adenosine In Recovery Of Automatic Circulation

Objective: Epinephrine given during closed-chest resuscitation increases blood flow across the coronary and cerebral circuits, which has been used for nearly 50 years. However, epinephrine worsens reperfusion, arrhythmias and intensifies postresuscitation myocardial and cerebrial dysfunction, which increase the early mortality. We investigated whether the combination of epinephrine plus adenosine could ameliorate such adverse effects and improve the successful rate of resuscitation.Methods: Part one of the paper, 30 health rabbits were randomly allocated to three groups after cardiac arrest induced by asphyxia. After 4min non-intervention interval, cardiopulmonary resuscitation (CPR) was started. After 4min CPR, the animals were randomly assigned to receive either 0.9% saline (group A, n=6) or epinephrine (bolus of 90ug/kg, group B, n=12) or epinephrine plus adenosine (bolus of 90ug/kg epinephrine followed by continuous infusion of 150ug/kg/min adenosine, group C, n=12). The rate of recovery of automatic circulation(ROAC) and successful CPR, the level of creatinkinase, creatinkinase-MB, and lactic acid in blood plasma were observed. The pathological changes of hippocampus neurons and myocardium were observed under optical microscopy and electronmicroscope. Part two of the paper, 43 health Wistar rats were randomly allocated to three groups. The model of cardiac arrest and the experiment grouping were just like Part one. Mesentery blood vessel, blood flow rate, the numbers and area of cardiac blood capillary, and small intestine tissue perfusion were observed.Results: ①With the rate of ROAC and successful CPR in asphyxia rabbits, group C(100%, 83.3%) were greater than that of group B (83.3%,58.3%)than that of group A(0,0);The level of creatinkinase, creatinkinase-MB, and lactic acid inblood plasma of group C(855 ± 191U/L, 1506 ± 692U/L, 8.4 + 2.7mmol/L) were lower than that of group B(1136 ± 332 U/L, 2365 + 957 U/L, 10.9 + 1.9 mmol/L), P<0.05;The damage in hippocampus neurons and myocardium of group B were greater than that of group C under optical microscopy and electronmicroscope. (2) With the rate of ROAC and successful CPR in asphyxia rats, group C(92.9%,64.3%) were greater than that of group B(78.6%,50%) than that of group A(60%,20%), P<0.05;With the numbers and area of cardiac blood capillary in the successful CPR rats , group C(448 ± 43, 0.41 ± 0.08%) were better than group B(302±25, 0.30+ 0.05%) and group A(215± 54, 0.38 + 0.12%), P<0.01;With the diameter and reperfusion of mesentery blood vessel and the velocity of microcirculation, group C were better than that of group B;Small intestine tissue perfusion of group C was better than that of group B, P<0.05. Conclusions: Adenosine could ameliorate adverse effects of epinephrine in CPR, improve microcirculation and tissue perfusion, protect the myocardium and cerebral, increase the rate of successful CPR. The method of epinephrine with adenosine maybe act as a new method in the clinic practice in CPR in the future.