Central Neuraxial Blockade (see Chapter 43 )

Some evidence has indicated that the effect of spinal or epidural anesthesia on liver blood flow and hepatic function is not clearly an anesthetic drug-induced alteration in hepatic function. Early human investigations by Kennedy and colleagues^{[44] [45]} showed that hepatic blood flow decreased during high spinal and epidural anesthesia and appeared to mirror simultaneous reductions in systemic arterial blood pressure. Other animal data have suggested reduced PBF and unchanged HABF with high epidural blockade, thus causing a decrease in THBF.^[46] These adverse changes can be reversed and hepatic blood flow maintained with the administration of vasopressors (such as dopamine or ephedrine) to restore PBF^{[47] [48] [49]} or fluid administration to maintain normal arterial blood pressure.^[50] Presumably, hypotension-induced reductions in hepatic blood flow are secondary to decreased splanchnic blood flow and, thus, reduced PBF. The impact of absorbed local anesthetic, with or without epinephrine, on cardiac output or splanchnic vascular resistance is unknown.