The volatility of an anesthetic agent is directly propoional to lowering the flow in the poal vein. Poal flow is maximally reduced by -
Halothane Effect of Anaesthesia on Hepatic Blood flow Hepatic blood flow usually decreases during regional and general anaesthesia. Multiple factors are probably responsible including :? - Direct and indirect effect of anaesthetic agent - The type of ventilation employed - Type of surgery being performed All anaesthetic agents indirectly reduce hepatic blood flow in propoion to any decrease in mean aerial blood pressure or cardiact output. - Decrease in cardiac output reduce hepatic blood flow reflex sympathetic activation which vasoconstricts both, the aerial and splanchnic circulation. Effect of different Anaesthetic procedures on hepatic flood flow If an adequate intravascular volume is maintained - Spinal and epidural anaesthesia decrease hepatic blood flow primarily by lowering aerial blood pressure. Where as - General anaesthesia usually decreases it through reduction in blood pressure and cardiac output and sympathetic stimulation. Effect of volatile anaesthetic agents on hepatic blood flow :? All volatile anaesthetic agents reduce poal hepatic blood flow. "This decrease is greatest with halothane and least with isoflurane". - Isoflurane appears to be the only volatile agent causing significant direct aerial vasodilation that can increase hepatic aerial blood .flow. - However even with isoflurane total hepatic blood flow decreases because the decrease in poal blood flow usually offsets any increase in hepatic aery. flow.
Ether
Halothane
Isoflurane
Enflurane