Platypnea-orthodeoxia Syndrome in a Patient with Cryptogenic Liver Cirrhosis: An Elusive Cause of Hypoxemia.

Platypnea-orthodeoxia syndrome (POS) has been defined as shortness of breath and hypoxemia in the upright position that improves with dorsal decubitus. This is a rare disorder caused by right-to-left shunts due to a persistent foramen ovale or pulmonary arteriovenous malformations. Hepatopulmonary syndrome can present with POS in the presence of pulmonary vasodilation and pulmonary arteriovenous communications in patients with liver disease. We report a case where the diagnosis of POS was made incidentally in a patient with cryptogenic liver cirrhosis. After other causes of hypoxemia were excluded, the diagnosis of right-to-left pulmonary shunt was confirmed by late opacification of the left heart chambers seen in a transthoracic echocardiogram. Interestingly, computerized tomography (CT) of the chest with contrast demonstrated a very prominent pulmonary vascular pattern extending to the periphery of the lungs. POS is a rare cause of hypoxemia that requires a high level of suspicion, and exclusion of more common causes of hypoxemia.