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

Abstract

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.

Keywords: atrial septal defects occluder; hypoxemic respiratory failure; patent foramen ovale; platypnea-orthodeoxia syndrome; positional dyspnea.

Figure 1. Agitated saline test during a transthoracic echocardiogram.

A positive agitated saline/bubble test was observed during the transthoracic echocardiogram, showing bubbles in the left side of the heart (* – left ventricle).

Figure 2. Transesophageal echocardiogram.

A large patent foramen ovale (*) with a bidirectional shunt was noted in the transesophageal echocardiogram.