Comparision Of Cardiotoxicity Of Different Local Anesthetics On Adult Rabbits

Objective: Chloroprocaine Hydrochloride and Procaine Hydrochloride are the local anesthetics of chloridated congener. Since 1960s, it has been used in infiltration anesthesia, nerve block and epidural anesthesia. In our country, it was produced by shanxi jingcheng haisi drug limited company and applied to the clinic in 2002. The object of this study is to compare cardiotoxicity of the four different local anesthetics ( chlorprocaine hydrochloride ,lidocaine ,ropivacaine and bupivacaine )of identical efficacy with each other on adult rabbits by simulating erroneous injection to blood vessel. The object is to evaluate the clinical safety of chlorprocaine hydrochloride accordingly and to provide experimental evidence for the clinical application.Methods:twenty-four healthy adult rabbits of both sexes weighing 1.65～2.5kg were randomly divided into 4 groups (n=6 each): groupⅠchlorprocaine hydrochloride (C), groupⅡlidocaine (L), groupⅢropivacaine(R) and groupⅣbupivacaine(B).modeling : the adult rabbits were anesthetized with 3% butaylone (30mg/kg)that was injected by the vein in ear .After the rabbit was anesthetized ,it was fixed on the operation table with constant temperature (18～25℃). The trachea was incised and mechanical ventilation was used .Vecuronium (0.1mg/kg)was applied to maintain skelaxin. The femoral artery was isolated and connected to the pressure transducer to measure blood pressure which was then connected to the computer with BL-420 bio-function experimental system. The femoral vein was isolated to pump local anesthetics. The liquid was supplied by the vein in ear , Two-lead ECG being monitored by inserting three acupuncture needles into the both upper limbs and left lower limb subcutaneouly. 1/ 1000 calparine (0. 1ml/ kg) was injected by vein in ear against coagulation . The plastic cannula with 1% calparine sodium chloride was intubated into left ventricle from left arteria carotis communis,and the left intraventricular pressure was recorded. The waveshape of left intraventricular pressure can be analysised automatically by BL-420 biological functional experimentation system .Every parameter value was displayed in the message window.administration: after modeling , the animal's every vital sign was stable . Lactated Ringer'S Solution (7ml/kg/h) was injected via vein in ear . 1% chlorprocaine hydrochloride (4mg/kg/min) was pumped in intravenous injection continuly (group C). 1% lidocaine(4mg/kg/min) was pumped as the first one (group L). 0.5% ropivacaine(1mg/kg/min) was pumped in the third group (group R)and 0.5% bupivacaine(1mg/kg/min) was used in the forth group(group B).observational index : animal's blood pressure(SBP/DBP) was recorded before the local anesthetics was given , and LVSP , LV±dp/dtmax were recored at the same time .By tracing normal ECG ,the time when arrhythmia was appeared in these animals was recored ,being the same as 50%HR ,70% LVSP ,70%SBP, 50% LV±dp/dtmax,and the time when the cardiac arrest . The electric wave has been observed after disappearing of it for 1 minute. The accumulated dose of corresponding local anesthetics was calculated at every point .Results: 1.the model was succeed , bleeding of intubing in left ventricle being parum ; the vital sign being stable after modeling .2. In each group ,the animal's body weight ,HR ,BP, LVSP and LV±dp/dtmax before injecting of local anesthetics were recorded respectively. There was no sigmificant difference in these indices(P>0.05).3. the comparision of time when the rabbits arrhythmia appearing. there is no statistics difference between C group and L group , (P>0.05).But the significant difference appears among C ,R,B group and L,R,B group ,Furthermore C