Changes in the hepatic perfusion index during the development of experimental hepatic tumours

A model of microscopic liver tumour has been developed in the Fisher rat by intraportal injection of 1.6 x 10(7) Walker 256 carcinosarcoma cells. Rats were studied at 2, 4 and 6 days after the inoculation of live Walker cells. A control group received dead Walker cells. No tumour was visible in control groups at 2, 4 and 6 days after inoculation. Similarly in rats injected with live cells no tumour was visible at 2 days after inoculation but at 4 and 6 days the percentage hepatic replacement was (mean +/- s.d.) 7.0 +/- 2.3 and 27.9 +/- 6.80 respectively. The hepatic perfusion index was significantly raised at 4 and 6 days after inoculation of live cells compared with control animals and those receiving viable cells after 2 days inoculation. Portal flow and portal venous inflow were significantly reduced when the hepatic perfusion index increased but hepatic arterial flow did not alter. Changes in the hepatic haemodynamics were accompanied by increases in the portal and splanchnic vascular resistance and an increase in the amount of arteriovenous shunting through the liver. These findings confirm studies that the hepatic perfusion index is useful in the detection of occult liver metastases but that the change is not a consequence of an increase in the hepatic arterial flow.