BACKGROUND: Infusion of pentastarch, with or without dopamine, has been used for cardiovascular support during epidural anesthesia, especially for maintaining normotension. The purpose of this study was to evaluate the effects of dopamine on hemodynamics, estimated hepatic blood flow, and the extraction ratio of indocyanine green during thoracic epidural anesthesia with the infusion of pentastarch. METHODS: Thirty healthy rabbits, weighing 2.5 - 3.5 kg, were evenly divided into three groups during thoracic epidural anesthesia; The control group received normal saline (10 ml/kg/hr), the pentastarch group received pentastarch (10 ml/kg/hr), and the dopamine group received pentastarch (10 ml/kg/hr) and a dopamine infusion (5 microgram/kg/min). Thoracic epidural block was done at T5 level with 0.4 ml/kg of 1% lidocaine. Hepatic blood flow was estimated by measuring the clearance of indocyanine green according to the constant infusion method before and 30 and 60 minutes after epidural anesthesia. The extraction ratio of indocyanine green, heart rate, mean arterial pressure, central venous pressure and splanchnic vascular resistance were also measured at the same time in the three groups. RESULTS: Heart rates, mean arterial pressures, estimated hepatic blood flow and splanchnic vascular resistance were unchanged but central venous pressure increased significantly at 30 and 60 minutes after epidural anesthesia in the dopamine group. The extraction ratio of indocyanine green remained unchanged 30 and 60 minutes after epidural anesthesia in all groups. CONCLUSIONS: Combined therapy with pentastarch and dopamine infusion can keep the cardiovascular stability, hepatic blood flow and splanchnic vascular resistance constant during thoracic epidural anesthesia in rabbits.