Platypnea-Orthodeoxia Syndrome in a Frail Elderly Patient: It's Not Always Pneumonia.

Platypnea-orthodeoxia syndrome (POS) is a rare condition characterized by positional dyspnea and arterial desaturation that worsens in the upright position and improves when supine. It is most commonly associated with intracardiac right-to-left shunting, often through a patent foramen ovale (PFO), and is frequently under-recognized. We report the case of an 84-year-old frail woman admitted with acute confusion and severe hypoxemia, initially treated for presumed community-acquired pneumonia. Despite high oxygen requirements, inflammatory markers were minimally raised, and imaging did not support an infection. A review of prior investigations revealed a PFO. Formal bedside positional oxygen assessment demonstrated reproducible orthodeoxia, confirming POS. A raised right hemidiaphragm was identified as a likely contributory factor. Given the patient's advanced frailty, a conservative approach to management was pursued. The patient was successfully weaned off oxygen and discharged home, to be nursed in a semi-recumbent position.