RESUMO
BACKGROUND: Levobupivacaine is known to be less cardiotoxic than racemic bupivacaine but some authors have reported there were no differences in cardiotoxic profiles between two agents. We will investigate the full course to cardiovascular collapse induced by bupivacaine stereoisomers in anesthetized dogs and would find out the differences if any, and explain the causative factors. METHODS: Twenty dogs were assigned to two groups, racemic bupivacaine group (BUP) and levobupivacaine group (LBUP), equally (n=10, each). Under general anesthesia each drug was infused continuously (0.5 mg/kg/min) until cardiovascuar collapse (CVC, MAP=40 mmHg) occurred. During the experiment, hemodynamic data, CO, SVR, PVR, ECG parameters and drug concen tration were gathered and analyzed. RESULTS: Two groups were not different in terms of dose for CVC, plasma drug concentration and time for CVC. MAP maintained initial values during the early period and declined during the late period without any between-group difference. Otherwise CO decreased continuously and significantly higher in LBUP than in BUP throughout. Calculated SVR showed the same feature as CO in opposite direction and was higher in BUP. Correlation test revealed high correlation between CONC and SVR or PVR and between CO and cSvO2. CONCLUSIONS: In assessment of cardiovascular collapse induced by stereoisomers of bupivacaine, monitoring with only MAP can lead to misinterpretation and invasive monitoring including CO or cSvO2 measurement might be needed.