Platypnea-Orthodeoxia Syndrome: A Rare Cause of Positional Respiratory Failure

Platypnea-orthodeoxia syndrome (POS) is a rare clinical entity characterized by dyspnea and arterial desaturation in the upright position. Hypoxia in POS has been attributed to the mixing of deoxygenated venous with oxygenated arterial blood via a shunt, with patent foramen ovale being the most commonly reported abnormality. A systematic evaluation is necessary to identify the underlying cause and promote an appropriate intervention. Here, we present the case of a 79-year-old female with a new diagnosis of POS during the workup of hypoxemic respiratory failure.