ABSTRACT
PURPOSE: Acute ligation of the portal vein in animals results in the pooling of blood in the splanchnic bed, and this is followed by rapid cardiovascular collapse and death. However, humans can withstand portal inflow occlusion because of portal collateral circulation. We tried to prove the development of portal collateral circulation for acute portal inflow occlusion through serial measurements of the portal pressure. METHODS: Our study was done on 187 patients who under went liver resection using portal triad clamping (PTC). We inserted a catheter into the right gastroepiploic vein and we measured the portal pressure before PTC, after PTC and just before the reperfusion of the last clamping. RESULTS: During liver resection, the portal pressure gradually decreased by 61.8 mmH2O in the normal liver group, 71.1 mmH2O in the chronic hepatitis group and 43.0 mmH2O in the cirrhosis group because of the development of collateral circulation. The differences among the three groups had no statistical significance. Moreover, there was no difference in the portal pressure decrease between the intermittent and continuous clamping groups. However, the decrease of portal pressure in the 21 patients with varices was much less than the decrease of portal pressure in those patients without varices (10 mmH2O vs. 62.7 mmH2O, p=0.008). In the more recent 20 cases, we additionally measured the portal pressure 15 minutes and 30 minutes after PTC. The pressure dereased rapidly for the first 15 minutes and the degree of pressure decrease after 15 minutes was minimal. CONCLUSION: The gradual decrease of portal pressure during PTC suggests the development of portal collateral circulation. This enables the patients to better tolerate liver ischemia during liver resection or transplantation. Most of the collateral circulations seemed to develop within the first 15 minutes of PTC.