Abstract

The effects of an intravenous bolus injection of subseizure doses of lidocaine and bupivacaine on the systemic and pulmonary circulation were studied in dogs anesthetized with nitrous oxide (N₂O)-halothane. The administration of high concentrations of halothane (1-1.5%) with N₂O produced a marked decrease in mean arterial pressure and cardiac output; a low concentration of halothane (0.5%) caused less cardiovascular depression. Mean pulmonary arterial pressure (MPAP) did not change after the intravenous administration of 10 mg/kg of lidocaine or 2.5 mg/kg of bupivacaine during N₂O-halothane (0.5-1.5%) anesthesia. These results indicate that an intravenous injection of subseizure doses of local anesthetics produces a marked cardiovascular depression and a slight change in MPAP during N₂O-halothane (1-1.5%) anesthesia in contrast to N₂O anesthesia.