Two Cases of Platypnoea-Orthodexia

Platypnoea-orthodexia syndrome is a rare cause of dyspnoea when hypoxaemia is induced by the upright position and relieved by recumbency. We report two cases in which platypnoea-orthodexia syndrome was present and caused by two different mechanisms: intracardiac shunt and intrapulmonary shunt. LEARNING POINTS: Platypnoea-orthodexia syndrome should be considered in the differential diagnosis of unexplained hypoxia. A high degree of suspicion is required to instigate initial investigations with either postural pulse oximetry or arterial gas analysis. The diagnosis must be based on the presence of both an anatomical and a functional component.