Simultaneous estimation of hepatic and portal blood flows by an indicator dilution technique.

Abstract

Abstract In 19 dogs, total hepatic blood flow (THBF) and portal blood flow (PBF) were measured using indicator dilution curves (IDC) obtained from hepatic and portal veins after injection of Cr 51 -labeled red cells into the cranial mesenteric artery. Samples were obtained simultaneously from the left branch of the portal vein and one left hepatic vein (40 experiments) and also, when possible, from one right hepatic vein (27 experiments). During each experiment, portal and hepatic arterial flows were estimated with two electromagnetic flowmeters. In 40 experiments, no significant difference was found between paired THBF, PBF, and portal fraction of THBF (PBF/THBF) estimated simultaneously by flowmeters and IDC. In the 27 experiments where THBF was measured simultaneously from one right and one left hepatic vein no significant difference existed between paired THBF. Similar results were obtained in another group of 5 dogs (9 experiments) with ligated hepatic artery. In these experiments, no significant difference was found between paired THBF and PBF estimated simultaneously by IDC. Such findings validate the sampling from one hepatic vein for THBF estimation and from the left branch of the portal vein for PBF estimation, demonstrating uniform mixing of the indicator in the portal vein and within intrahepatic circulation. Some high absolute flows observed using both methods could be explained by the effect of radiopaque material. In 5 additional dogs, radiopaque material (50 ml.) was shown to increase the cardiac output, PBF, and THBF significantly without major changes in the hepatic arterial blood flows. These data show the usefulness of the Stewart-Hamilton method for simultaneous estimation of THBF, PBF, and portal fraction of THBF in normal dogs after injections of the indicator into the cranial mesenteric artery. Preliminary data in 11 cirrhotic subjects undergoing umbilico-portal and hepatic vein catheterization indicate that the portal fraction of THBF can be estimated by this method, assuming uniform mixing of the indicator in the portal vein. The portal fraction should be reliable since the portosystemic collaterals resulting in loss of indicator occurred before the sampling sites.