Systemic toxicity and resuscitation in bupivacaine-, levobupivacaine-, or ropivacaine-infused rats

We compared the systemic toxicity of bupivacaine, levobupivacaine, and ropi vacaine in anesthetized rats. We also compared the ability to resuscitate r ats after lethal doses of these local anesthetics. Bupivacaine, levobupivac aine, or ropivacaine was infused at a rate of 2 mg . kg(-1) . min(-1) while electrocardiogram, electroencephalogram, and arterial pressure were contin uously monitored. When asystole was recorded, drug infusion was stopped and a resuscitation sequence was begun. Epinephrine 0.01 mg/kg was administere d at 1-min intervals while external cardiac compressions were applied. Resu scitation was considered successful when a systolic arterial pressure great er than or equal to 100 mm Hg was achieved within 5 min. The cumulative dos es of levobupivacaine and ropivacaine that produced seizures were similar a nd were larger than those of bupivacaine. The cumulative doses of levobupiv acaine that produced dysrhythmias and asystole were smaller than the corres ponding doses of ropivacaine, but they were larger than those of bupivacain e. The number of successful resuscitations did not differ among groups. How ever, a smaller dose of epinephrine was required in the Ropivacaine group t han in the other groups. We conclude that the systemic toxicity of levobupi vacaine is intermediate between that of ropivacaine and bupivacaine when ad ministered at the same rate and that ropivacaine-induced cardiac arrest app ears to be more susceptible to treatment than that induced by bupivacaine o r levobupivacaine.