Lidocaine, bupivacaine, etidocaine, and epinephrine-induced arrhythmias during halothane anesthesia in dogs.

Arrhythmogenic doses of epinephrine were determined in six mongrel dogs anesthetized at 1.4 MAC halothane initially in the absence of local anesthetics and then at increasing arterial plasma levels of lidocaine, bupivacaine, and etidocaine. The authors gave epinephrine intravenously at 5 microgram/kg/min and calculated the arrhythmogenic dose as a function of time until two or more premature ventricular contractions occurred within a 10-sec period. The control arrythmogenic dose of epinephrine was 4.66 +/- 0.46 microgram/kg (mean +/- SEM). Arrythmogenic doses of epinephrine were increased significantly after each dose of lidocaine, bupivacaine, and etidocaine. With the largest doses studied, local anesthetic plasma levels were frequently in the toxic range. The data show that lidocaine, bupivacaine, and etidocaine equally protect against epinephrine-induced arrhythmias in dogs anesthetized with halothane.