Hepatopulmonary Syndrome

Hepatopulmonary syndrome was first proposed in 1977 based on autopsy and clinical findings. Autopsies showed dilated pulmonary vasculature in patients with liver cirrhosis and were thought to cause some of the pulmonary manifestations seen in patients with chronic liver disease. Hepatopulmonary syndrome is defined as reduced arterial oxygen saturation due to dilated pulmonary vasculature in the presence of advanced liver disease or portal hypertension. The diagnostic criteria for hepatopulmonary syndrome include:  Defined as <80 mm Hg while breathing room air or alveolar-arterial oxygen gradient (A-aO2), ≥15 mm Hg while breathing room air. In patients older than 64, A-aO2 >20 mm Hg is considered diagnostic (these patients should be resting in a seated position).  Dilatation as shown by a positive contrast-enhanced echocardiography or by radioactive lung-perfusion scanning (demonstrating a brain shunt fraction of >6%).  Elevated pressure within the portal venous system with or without cirrhosis. The severity of hepatopulmonary syndrome is classified based on the following PaO levels: PaO2 ≥80 mm Hg with A-aO2 ≥15 mm Hg while breathing room air. PaO2 ≥60 mm Hg to <80 mm Hg with A-aO2 ≥15 mm Hg while breathing room air.  PaO2 ≥50 mm Hg to <60 mm Hg with A-aO2 ≥15 mm Hg while breathing room air. PaO2 <50 mm Hg with A-aO2 ≥15 mm Hg while breathing room air, or PaO2 <300 mm Hg while breathing 100% oxygen .