Platypnea-orthodeoxia syndrome

Platypnea-orthodeoxia (P-O) syndrome is an under-diagnosed condition characterized by dyspnea and deoxygenation when changing from a recumbent to an upright position

Platypnea–orthodeoxia syndrome is a condition in which a person has shortness of breath and low oxygen saturations when upright (platypnea and orthodeoxia), but no symptoms when lying down.

It is usually caused by increased right-to-left shunting of blood on assuming an upright position, with normal pressure in the right atrium.

It may also be caused by intrapulmonary shunting combined with extensive pulmonary lesions or severe V/Q mismatching.

Common causes:

Atrial septal defect (ASD) or persistent foramen ovale (PFO). present in ~20-25% of the population.

Position-dependent shunting in combination with right-to-left shunt causes hypoxia, from either right atrial pressure > left atrial pressure, or mechanical distortion – of either the fossa ovalis itself or the flow of blood from the IVC to the ASD/PFO

Pericardial effusion

Constrictive pericarditis

Aortic aneurysm

Tricuspid regurgitation

Mediastinal shift


Multiple pulmonary emboli

Pulmonary emphysema

Radiation-induced bronchial stenosis

Hepatopulmonary syndrome

Amiodarone toxicity of the lungs

Pulmonary A-V communications

PCP pneumonia

fat embolism syndrome


Parkinson disease

Bilateral thoracic sympathectomy


Hepatic cirrhosis



Closure of the ASD or PFO

temporary closure by balloon occlusion

permanent occlusion by open surgery or percutaneous intervention

Intracardiac shunting is the most common cause.

The disorder can also arise from pulmonary arteriovenous malformations.

Evaluation includes positional assessment of shunting, involving an echocardiographic bubble study and color Doppler assessment.

Definitive management involves surgical or percutaneous closure of the inter-atrial communication.

Treat any associated condition.

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