Lidocaine, Bupivacaine, Etidocaine, and Epinephrine-induced Arrhythmias during Halothane Anesthesia in Dogs

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Abstract
Arrhythmogenic doses of epinephrine were determined in 6 mongrel dogs anesthetized at 1.4 MAC [minimum anesthetic concentration] halothane initially in the absence of local anesthetics and then at increasing arterial plasma levels of lidocaine, bupivacaine and etidocaine. Epinephrine was given i.v. at 5 .mu.g/kg per min and calculated the arrhythmogenic dose as a function of time until 2 or more premature ventricular contractions occurred within a 10 s period. The control arrhythmogenic dose of epinephrine was 4.66 .+-. 0.46 .mu.g/kg (mean .+-. SEM [standard error of the mean]). Arrhythmogenic 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. Lidocaine, bupivacaine and etidocaine equally protect against epinephrine-induced arrhythmias in dogs anesthetized with halothane.