Effect of Clonidine Pretreatment on the Cardiovascular Toxicity Induced by Inrravenous Bupivacaine in Rabbits

Abstract

This study was performed to evaluate the influence of clonidine pretreatment on the car- diovascular toxic effects of bupivacaine overdose induced by constant intravenous infusion. Thirty male rabbits were used for this study and they were divided into saline pretreatment group(15) and clonidine-pretreatment group(15). The changes of mean arterial pressure, heart rate and electrocardiogram by the bupivacaine-induced toxic effect during intravenous infusion of bupivacaine were observed. The results were as follows; 1. Mean arterial pressure was significantly decreased in clonidine-premedicated group compared with control group (P<0.01) before infusion of bupivacaine, but the times occuring 25% and 50% decrease of mean arterial pressure were significantly prolonged in clonidine group compared with control group (P <0.001 ). 2. Heart rate was significantly decreased in clonidine group compared with control group (P<0.01) before infusion of bupivacaine, but the times occuring 25% and 50% decrease of heart rate were significantly prolonged in clonidine group compared with control group (P< 0.001). 3. The times occuring the first QRS modification and first dysrhythmia and the final systole were significantly prolonged in clonidine group compared with control group (P < 0.001). In conclusion, clonidine given prophylactically delays the cardiotoxicity caused by bupivacaine overdose snd does not accentuate the subsequent hypotension.