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
Pulmonary
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
Autonomic
Parkinson disease
Bilateral thoracic sympathectomy
Abdominal
Hepatic cirrhosis
Ileus
MANAGEMENT
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.