The effects of thoracic epidural anesthesia on hepatic blood flow in patients under general anesthesia

Hepatic hypoperfusion is regarded as an important factor in the pathophysiology of perioperative liver injury. Although epidural anesthesia (EDA) is a widely used technique, no data are available about the effects on hepatic blood flow of thoracic EDA with blockade restricted to thoracic segments in humans.

In 20 patients under general anesthesia, we assessed hepatic blood flow index in the right and middle hepatic vein by use of multiplane transesophageal echocardiography before and after induction of EDA. The epidural catheter was inserted at TH7-9, and mepivacaine 1% with a median (range) dose of 10 (8-16) mL was injected. Norepinephrine (NE) was continuously administered to patients who demonstrated a decrease in mean arterial blood pressure below 60 mm Hg after induction of EDA (EDA-NE group). The other patients did not receive any catecholamine during the study period (EDA group). A further 10 patients without EDA served as controls (control group).

In five patients, administration of NE was necessary to avoid a decrease in mean arterial blood pressure below 60 mm Hg. Thus, the EDA-NE group consisted of five patients and the EDA group of 15. In the EDA group, EDA was associated with a median decrease in hepatic blood flow index of 24% in both hepatic veins (P < 0.01). In the EDA-NE group, all five patients showed a decrease in the blood flow index of the right (median decrease 39 [11-45] %) and middle hepatic vein (median decrease 32 [7-49] %). Patients in the control group showed a constant blood flow index in both hepatic veins. Reduction in blood flow index in the EDA group and the EDA-NE group was significant in comparison with the control group (P < 0.05). In contrast to hepatic blood flow, cardiac output was not affected by EDA.

We conclude that, in humans, thoracic EDA is associated with a decrease in hepatic blood flow. Thoracic EDA combined with continuous infusion of NE seems to result in a further decrease in hepatic blood flow.