Hepatosplanchnic circulation

Studies on the intestinal blood flow have reported either a moderate decrease in dogs (Bergofsky46), in conscious rats (Hordnes47), or no change in ewes (Mantalon15).

On the contrary, hepatic blood flow in animals has been reported as unchanged10 or increased61.

In human beings62 using indocyanin green clearance, hepatic blood flow has been shown to be maintained even for 16-hour exposures at 1.5 ata FiO2 = 1.

The preservation and even an increase in hepatic blood flow is remarkable when compared to the nearly universal decrease of blood flow in other organs. It may be accounted for by the fact that the greater part of the hepatic blood flow is of portal venous origin and that the increase in PO2 in the portal venous blood is much smaller than in the arterial blood. Taking into account the balance between hepatic artery and portal vein where hepatic blood flow is concerned, hyperoxia could cause vasoconstriction of the hepatic artery thus decreasing arterial blood flow into the liver. Portal flow would increase to compensate. Since this involves venous blood, the increase in hepatic PO2 would be moderate, which could explain that the hepatic blood flow does not decrease.

0 0

Post a comment