Platypnea-Orthodeoxia Syndrome: A Simple Clinical Observation that Heralds Critical but Treatable Disease

[...]platypnea and orthodeoxia have been associated with other conditions including patent foramen ovale, atrial septal defect, pericardial effusion, aortic aneurysm, constrictive pericarditis, arteriovenous communications, pneumonectomy, amiodarone toxicity, autonomic dysfunction, [2,4], and hepatopulmonary syndrome (HPS). [...]POS may occur with pulmonary vascular shunting secondary to arteriovenous malformations in the lung [4]. Since treatment of POS depends on the cause, the first step is to determine the etiology of POS.