Hepatopulmonary syndrome.

Hepatopulmonary syndrome is caused by intrapulmonary vasodilation that leads to abnormal arterial gas exchange in the setting of liver disease or portal hypertension. It is seen in up to 15% of cirrhotics and is an increasingly common indication for liver transplantation. Testing for the presence of oxygenation abnormalities and intrapulmonary vasodilation is needed to make the diagnosis. Excess production of nitric oxide in the lung contributes to pulmonary vasodilation and may be triggered by the release of mediators from the damaged liver. No medical therapies are established as effective, and liver transplantation is the only documented curative treatment.