The effects of different lidocaine continuous rate infusion (CRI) on cardiac rhythm were studied in dogs anesthetized with isoflurane receiving increasing epinephrine doses. For this study, 10 dogs were used, each one anesthetized four times, within a two week interval. Anesthesia was induced with propofol, 8mg/kg, and maintained with isoflurane at 1.5 MAC. Animals were submitted to four different treatments. The three lidocaine groups consisted of a loading dose of lidocaine, 1mg/kg, followed by a lidocaine CRI at the rates of 50μg/kg/h (G50), 100μg/kg/h (G100) and 200μg/kg/h (G200). The control group (GC) received NaCl at 0.9% bolus and CRI. Variables were measured 30 minutes after induction (baseline) and then the CRI started. Ten minutes after baseline measurements, data was collected again and the infusion of 1μg/kg/min of epinephrine started. New data collection was done after ten minutes, and then the epinephrine dose was increased to 2μg/kg/min, until reaching 5μg/kg/min. Compared to GC, there was a reduction in ectopic beats and second degree atrioventricular block in groups treated with lidocaine. It was concluded that the isoflurane-lidocaine combination reduces the appearance of some arrhythmias.
dog; anesthesia; lidocaine; arrhythmia; epinephrine
