Hepatopulmonary syndrome is low levels of oxygen in the blood caused by widening (dilation) of the small arteries of the lungs that occurs in people with high blood pressure in the vein that drains the liver (portal vein).
Hepatopulmonary syndrome results from the microscopic widening of arteries and veins in the lungs in people with chronic liver disease. Because of the widening, the workload of the heart increases, causing blood to be pumped to the body before it has absorbed sufficient oxygen, leading to a decreased level of oxygen in the blood.
People have shortness of breath that is often worse when sitting up and is relieved when they lie down. The level of oxygen in the blood also decreases when the person sits up. Most people also have symptoms of chronic liver disease, such as small red spots on the skin (spider angiomas).
Doctors suspect hepatopulmonary syndrome in people with liver disease who develop shortness of breath (particularly when lying down). If hepatopulmonary syndrome is suspected, doctors measure the amount of oxygen in the blood using a sensor placed on a finger (pulse oximetry). Sometimes doctors also take a sample of blood after the person has been breathing room air and again after the person breathes oxygen and measure the levels of oxygen in the samples.
Test that can help establish the diagnosis include a type of echocardiography in which a solution is injected intravenously (contrast echocardiography) and a nuclear lung scan.
The main treatment is supplemental oxygen to relieve shortness of breath. Somatostatin, which reduces widening of the blood vessels, may be helpful in some people. Hepatopulmonary syndrome may regress after liver transplantation or if the underlying liver disease subsides.