- Platypnea-orthodeoxia (P-O) syndrome is an under-diagnosed condition characterized by dyspnea and deoxygenation when changing from a recumbent to an upright position
- 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
- ASD or PFO with position-dependent shunting, often in combination with one of the conditions below.
- Other Cardiac
— Pericardial effusion
— Constrictive pericarditis
— Aortic aneurysm
— Multiple pulmonary emboli
— Pulmonary emphysema
— Radiation-induced bronchial stenosis
— Hepatopulmonary syndrome
— Amiodarone toxicity of the lungs
— Pulmonary A-V communications
— PCP pnuemonia
— fat embolism syndrome
— Parkinson disease
— Bilateral thoracic sympathectomy
— Hepatic cirrhosis
- supine and upright PaO2 measurement
- tilt transesophageal echocardiogram with bubble study (<100% sensitive) – diagnosis of the shunt can be difficult
- look for other underlying causes
- Closure of the ASD or PFO
- Treat any associated condition
— A case associated with Parkinson’s disease was attributed to postural hypotension, and improved with fludrocortisone.
— A case associated with radiation-induced bronchial stenosis was relieved by bronchial dilation initially, and later by bronchial stenting.
— A case associated with bilateral thoracic sympathectomy (van Heerdon 2004) was treated initially with noradrenaline and almitrine.