Effect of phenoxybenzamine (POB) on portal venous pressure in patients with portal hypertension.

In order to assess an effect of phenoxybenzamine (POB) on portal circulation, POB (0.5-1.0 mg./kg.) was administered intravenously to six patients with portal hypertension and two patients without portal hypertension. In patients with portal hypertension, POB reduced portal venous pressure (PVP) from 362.5 +/- 53.8 mm. H2O to 282.5 +/- 50.4 mm. H2O (P less than 0.001) where central venous pressure (CVP) was maintained constant. In patients without portal hypertension, change in PVP was in parallel with that in CVP where the decrease in PVP was regarded as not specific. This preferential reduction of PVP in portal hypertension seemed to implicate functional vasoconstriction of the portal venous system. In the treatment of bleeding esophageal varices, use of POB with blood transfusion after decompression of the Sengstaken-Blakemore tube should be beneficial because of its prolonged effect of lowering PVP and preventing ischemic liver damage.