Hemodynamic Interactions of Lidocaine and Diltiazem During Halothane Anesthesia in Dogs

Kim, Seong Deok; Chung, Ik Soo

Abstract

The hemodynamic interactions of lidocaine and diltiazem during halothane anesthesia were studied using eight mongrel dogs. The animals were anesthetized with inhalation of 1.0 MAC of halothane(GroupH) continuously throughout the experiment. 30 minutes after the inhalated and end-tidal halothane concentration reached equilibrium, 0.2 mg/kg of diltiazem was given intravenously over 2.0 min. From that point 8 ug/kg/min of diltiazem was continuously infused (group HD). Then a small dose of lidocaine(group HD1; iv bolus 1.5 mg/kg over l min, followed by continuous iv infusion at the rate of O.l mg/kg/min for 30 min) and a large dose of lidocaine (group HDI; iv bolus 1.0 mg/kg over I min, followed by continuous iv infusion at the rate of 0.3 mg/kg/min for 30 min) were administered serially. In group HD, PR interval increased significantly(22.2%) and coronary perfusion pressure decreased significantly(l9.3%), compared with group H. Compared with group H, significant increase in PR interval(44.4%), and decreases in diastolic arterial blood pressure(28%), mean arterial blood pressure(20.1%) and rate pressure product(35.2%) occured in group HD1. In group HDL, a significant decrease in heart rate(20.7%) and coronary perfusion pressure(33.0%) also occured, compared with group H. No significant changes in oxygen transport and consumption existed among groups. The most significant result of the injection of lidocaine diltiazem during halothane anesthesia in dogs was increase in PR interval. Even in high doses of lidocaine, only slight hemody- namic depression resulted and no significant changes in tissue oxygenation occurred. Therefore, the combined administration of diltiazem and lidocaine in clinical doses during halothane anes- thesia in dogs is a relatively safe administrative method.