Blood flow and blood oxygen partial pressure of the azygos vein in portal hypertension evaluated by the catheter method

To evaluate the clinical significance of blood flow in the azygos vein and the oxygen partial pressure in azygos venous blood in portal hypertension, we examined 25 patients with liver cirrhosis, 4 with chronic hepatitis, 4 with idiopathic portal hypertension (IPH) and 16 controls by the continuous thermodilution method and azygos venous blood sampling. The azygos venous flow was significantly higher in the patients with chronic liver diseases than in the controls. There was a significant correlation between azygos venous flow and hepatic venous pressure gradient. In the patients with liver cirrhosis, about one half of the azygos venous flow was assumed to represent upward collateral flow, as the azygos venous flow was 3.4% of cardiac output in the controls, 6.3% in the liver cirrhosis patients, and 5.1% in the IPH patients. Oxygen partial pressure in azygos venous blood was higher in patients with portal hypertension, especially in the IPH patients, which indicates that part of splenic flow drains into the azygos vein.