Hemodynamics Actions of Lidocaine during Halothane Anesthesia in Dogs

Kim, Kay Yong; Kim, Seong Deok

Abstract

The hemodynamic responses to lidocaine were studied in eight mongrel dogs during halothane anesthesia. The animals inhaled 1 MAC of halothane (group H). During halothane anesthesia, a small dosage of lidocaine (group H; iv bolus 1.5 mg/kg over 1 min, followed by continuous iv infusion with 0.1 mg/kg/min), and a large dosage of lidocaine (group HL; iv bolus 1.0 mg/kg over 1 min, followed by continuous iv infusion with 0.3mg/kg/min) were administered for 30 min, respectively. One MAC of halothane anesthesia decreased the heart rate (10.9%), systolic blood pressure (13.3%), rate pressure product (22.5%), coronary perfusion pressure (16.5%), cardiac index (17.6%), and left ventricular stroke wark index (22.5%) compared with the control. Compared with group H, a small dosage of lidocaine (group H(1)) only significantly decreased the heart rate by 10%, but it seemed to decrease the above mentioned paramenters further. A large dosage of lidocaine (group H L) decreased the heart rate (27.3%), systolic blood pressure (26.0%), cardiac index (35.1%) and rate pressure product (46.0%), compared with the control value, and significantly increased the PR interval in ECG (30%). Although all the parameters indicating oxygen demand and supply were decreased, the shunt ratio was decreased and the alveolar-arterial oxygen tension difference was maintained at the control level. This study demonstrates that the hemodynamic changes by lidocaine might be induced by direct cardiac effect, not by the effect on peripheral vessels and that oxygenation might be well maintained during lidocaine infusion in a clinical dose.