A case of unexplained cyanosis.

It is now clear that hepatopulmonary syndrome (HPS) may occur and contribute significantly to gas exchange abnormalities in the setting of other cardiopulmonary abnormalities. Since there is no gold-standard diagnostic test for HPS, diagnosis rests on documenting arterial oxygenation abnormalities resulting from intrapulmonary vasodilatation in the setting of liver disease. Retrospective studies suggest that many patients with HPS develop progressive intrapulmonary vasodilatation over time and that mortality is significant. This case highlights the clinical value in investigating for HPS and right-to-left shunts when confronted with a patient presenting with unexplained hypoxia in combination with platypnoea and/or orthodeoxia.