Keywords Humans, COVID-19, Dyspnea, Foramen Ovale, Patent, Hypoxia, Patient Positioning, Platypnea Orthodeoxia Syndrome, Posture, SARS-CoV-2, Syndrome, Heart septal defects, atrial; dyspnea; foramen ovale, patent; platypnea orthodeoxia syndrome; supine position Abstract Platypnea-orthodeoxia syndrome is a rare condition characterized by positional dyspnea and hypoxemia, with symptoms presenting in the upright position and improving when recumbent.