When Standing Takes Your Breath Away: A Clinical Case of Platypnea-Orthodeoxia Syndrome

Platypnea-orthodeoxia syndrome (POS) is characterized by dyspnea due to a marked fall in blood oxygen saturation while assuming standing or sitting positions. It is a rare condition with an unknown prevalence. The triggering role may remain unclear in a considerable number of patients. We present an 85-year-old female admitted to the emergency department (ED) due to aphasia, deviation of the right lip commissure, tachycardia, and dyspnea. History included a right femur shaft fracture in the previous month, and she was enrolled in a rehabilitation program. She already had a history of multiple falls and cerebrovascular disease. On physical examination, she was apyretic, normocardic, and normotensive, although tachypneic. Peripheral oxygen saturation was considerably different, being higher with the patient in the supine position when compared to a bed elevation of 30º. Lung fields were clear to auscultation, and cardiac examination showed no regurgitant heart murmurs or precordial impulses. No peripheral limb edema was noted. The neurologic examination was unremarkable. Her first arterial blood sample revealed hypoxemic respiratory failure. The remaining complementary diagnostic exams (CDE) were normal, apart from some old rib and spine fractures visible on a CT scan. The patient was admitted to the internal medicine ward for further investigation. After a long march of CDE, a transesophageal echocardiogram revealed the cause of POS, a patent foramen ovale. A contrast test with agitated saline showed a significant passage of bubbles from the right atrium to the left during the Valsalva maneuver, confirming intracardiac right-left shunt, and also an aneurysmal dilatation and lipomatous hypertrophy of the interatrial septum. Percutaneous closure is the surgical treatment procedure used. The intervention was discussed with the Department of Cardiology and a conservative approach was decided.  In recent years, increasing articles and case reports of POS have elicited the attention of physicians, who have acquired a greater awareness and have become more accurate in diagnosing and treating patients with unexplained or paroxysmal dyspnea. The challenge is to understand which are the higher-risk patients in order to refer them for primary percutaneous closure.