Comparing the toxic dosage of levobupivacain, ropivacaine and bupivacaine over cardiovasculer system effects in experimental animal model

OBJECTIVES: In this study, following the administration of bupivacaine, levobupivacaine and ropivacaine, we aim to compare the cardiotoxic dosages and cardiotoxic effects of each agent.MATERIALS AND METHODS: Eighteen adult male mixed breed dogs weighing 20-25 kg were included in the study. The agents that choosen as lochal anesthetics were bupivacaine (Group B), levobupivacaine (Group L), ropivacaine (Group R). The subjects of the experiment were divided randomly into three groups that each one containing six dogs. Anesthesia was supplied by administering of 100 mg ketamin and 5 mg midazolame before the study and intravenous catheter was placed. Electrocardiography (ECG), saturation of peripheric oxygene (SPO2) and heart rate (HR) monitorizations were performed. During electrocardiographic observation,aritmy,ventricular fibrilation, asistol accepted as ECG alterations. IV cardiac toxic dosages calculated for Group B,Group L and Group R respectively determined as 3 mg/kg, 150 mg, 3 mg/kg and total toxic effective dosage calculated for each group. Local anesthetics (bupivacaine, levobupivacaine, and ropivacaine) were administered 30mg dk-1 intravenously by constant rate in each group. When ECG changes; arrhyhtmias, ventricular fibrillation and asistoly were determined, drug administration was stopped and bupivacaine causes fetal aritmy at lower dosages than ropivacaine and levobupivacaine. Measurements of SPO2 and ECG were performed at 1., 2., 3., 4., 5., 10., 15.,20., 25., and 30. minutes and recorded for each group.RESULTS: ECG changes after third minute between 3. and 4. minutes were determined in bupivacaine group and cardiotoxic dosage of bupivacaine was calculated as 121.83 ± 2.22 mg. There was no significant difference between SPO2 and HR values at 1.,2.,3.,4.,5.,10.,15.,20.,25. and 30. minutes. ECG changes after third minute between 3. and 4. minutes were determined in levobupivacaine group and cardiotoxic dosage for levobupivacaine was calculated as 135.83±8.01 mg. There was no significant difference between SPO2 and HR values at 1.,2.,3.,4.,5.,10.,15.,20.,25. and 30. minutes. ECG changes after fifth minute between 5 and 6. minutes were determined in ropivacaine group and cardiotoxic dosage of ropivacaine was calculated as 205.00 ± 5.47mg. There was no significant difference between SPO2 and HR values at 1.,2.,3.,4.,5.,10.,15.,20.,25. and 30. minutes. When effective dosages were compared statistically between groups, the effective dosage of levobupivacaine was found significantly higher than Bupivacaine (p<0.01). The effective dosage of levobupivacaine was found significantly lower than the ropivacaine group statistically (p<0.01). The effective dosage of ropivacaine group was found statistically significantly higher than bupivacaine group (p<0.01). The effective dosage of ropivacaine group was found statistically significantly higher than Levobupivacaine group (p<0.01).As the results of our study, when ECG changes in all groups were eveluated, arrhythmias were seen in all bupivacaine groups and ventricular fibrillation that replied cardiac resuscitation was seen in two animals. Although arrhthmias were seen in all levobupivacaine and ropivacaine animals, ventricular fibrillation wasn?t seen in these groups. Asistoly was not seen in any animals in three groups.CONCLUSION: The of our study the intravenous toxic dosage of ropivacaine that induced ECG changes (arrhytmias, ventricular fibrillation and asistoly) was determined higher than the toxic dosage of levobupivacaine. The dosages that induce ECG changes of levobupivacaine and ropivacaine were determined significantly more than bupivacaine toxic dosage. Although arrhythmia was determined in all bupivacaine, levobupivacaine, ropivacaine groups, ventricular fibrillation rhythm resulted death only in one animal at bupivacaine group.In conclusion, levobupivacaine and ropivacaine were observed as more reliable than bupivacaine and ropivacaine was observed as more reliable than levobupivacaine, when the cardiac effects were considered.