Summary about Disease
Platypnea-Orthodeoxia Syndrome (POS) is a rare condition characterized by shortness of breath (platypnea) and a decrease in arterial oxygen saturation (orthodeoxia) that occur when a person is in an upright (sitting or standing) position and are relieved when lying down. It's caused by intracardiac or intrapulmonary shunting of blood. This means blood bypasses the normal oxygenation process in the lungs.
Symptoms
Shortness of breath that worsens when sitting or standing.
Decreased oxygen saturation (SpO2) when sitting or standing.
Lightheadedness or dizziness upon standing.
Cyanosis (bluish discoloration of skin and mucous membranes) in severe cases.
Fatigue.
Causes
The underlying causes involve abnormal blood flow pathways that result in deoxygenated blood bypassing the lungs and entering the systemic circulation. The main categories of causes are:
Intracardiac shunts: Patent foramen ovale (PFO), atrial septal defect (ASD), or other heart defects that allow blood to flow from the right atrium to the left atrium. These shunts are usually not problematic until other conditions change the pressure gradients in the heart.
Intrapulmonary shunts: Arteriovenous malformations (AVMs) in the lungs, pulmonary fistulas, or diffuse lung disease. These allow blood to bypass the alveoli (air sacs) where oxygen exchange occurs.
Anatomical abnormalities or changes affecting pulmonary vascular resistance: Scoliosis, pneumonectomy (lung removal), cirrhosis with hepatopulmonary syndrome, or other conditions that distort or alter the pressures within the chest cavity or pulmonary vasculature.
Medicine Used
Treatment focuses on addressing the underlying cause of the shunt. There is no single medicine specifically for POS, but several medications are used to treat symptoms and prevent worsening of the condition.
Supplemental Oxygen: To increase blood oxygen levels.
Pulmonary Vasodilators: In some cases, medications to reduce pulmonary artery pressure (e.g., sildenafil, prostacyclin analogs) may be used if pulmonary hypertension is present.
Anticoagulants: If paradoxical embolism is a risk (e.g., in PFO with right-to-left shunting), blood thinners may be prescribed to prevent stroke. The primary treatment is often intervention to close the shunt:
PFO or ASD Closure: Percutaneous transcatheter closure or surgical repair of the defect.
AVM Embolization: Blocking the abnormal blood vessels in the lungs.
Is Communicable
No, Platypnea-Orthodeoxia Syndrome is not a communicable disease. It is caused by structural or functional abnormalities within the individual's body, not by an infectious agent.
Precautions
Avoid prolonged sitting or standing: Especially in situations where shortness of breath is likely to occur.
Stay hydrated: Dehydration can worsen orthostatic symptoms.
Avoid activities that exacerbate symptoms: Listen to your body and avoid activities that trigger or worsen shortness of breath or dizziness.
Follow medical advice: Adhere to prescribed medications and recommendations from your healthcare provider.
Oxygen therapy: Use supplemental oxygen as prescribed.
How long does an outbreak last?
Because Platypnea-Orthodeoxia Syndrome is not caused by an infection, the concept of an "outbreak" is not applicable. The duration of symptoms depends on the underlying cause and whether it can be treated effectively. Symptoms can be chronic (long-lasting) if the underlying cause is not corrected.
How is it diagnosed?
Diagnosis involves a combination of physical examination, patient history, and diagnostic testing.
Clinical Observation: Noting the presence of platypnea and orthodeoxia. Oxygen saturation is measured in both the supine (lying down) and upright positions. A significant drop in SpO2 upon standing is suggestive.
Echocardiography: Transthoracic echocardiogram (TTE) with bubble study or transesophageal echocardiogram (TEE) to identify intracardiac shunts like PFO or ASD. The bubble study involves injecting agitated saline into a vein to visualize bubbles crossing from the right to the left side of the heart.
Pulmonary Angiography or CT Angiography: To identify pulmonary AVMs.
Arterial Blood Gas (ABG): Measures oxygen and carbon dioxide levels in the blood to assess the severity of hypoxemia (low blood oxygen).
Right Heart Catheterization: In some cases, to measure pressures in the heart and lungs and assess for intracardiac shunting.
Timeline of Symptoms
The onset and progression of symptoms can vary widely depending on the underlying cause.
Sudden Onset: Can occur after events that acutely alter pulmonary or cardiac pressures (e.g., after pneumonectomy, pulmonary embolism).
Gradual Onset: Symptoms may develop gradually over time, especially with progressive lung disease or slow enlargement of a shunt.
Episodic: Symptoms may be triggered by specific activities or conditions (e.g., dehydration, exertion). The timeline is highly individualized and depends on the specific pathology.
Important Considerations
POS is a rare but important cause of shortness of breath, especially when it is positional.
Early diagnosis and treatment of the underlying cause are crucial to improve symptoms and prevent complications.
A multidisciplinary approach involving cardiologists, pulmonologists, and other specialists is often necessary for optimal management.
Patients should be educated about their condition and strategies to minimize symptoms.
The presence of POS should prompt a thorough evaluation for underlying cardiac or pulmonary abnormalities.