What is hepatopulmonary syndrome (HPS)?

From the Guidelines

Hepatopulmonary syndrome is a condition characterized by intrapulmonary vascular dilatations in the setting of portal systemic shunting, leading to increased morbidity and mortality, but is generally reversible after liver transplantation. This condition occurs when liver dysfunction causes blood vessels in the lungs to dilate abnormally, creating a mismatch between ventilation and perfusion, resulting in blood passing through the lungs without proper oxygenation 1. Patients with hepatopulmonary syndrome typically experience shortness of breath, particularly when standing or sitting, low oxygen levels that worsen in upright positions, and may have clubbing of fingers, cyanosis, and spider angiomas on the skin.

Key Characteristics

• The presence of hepatopulmonary syndrome is associated with increased morbidity and mortality, but is generally reversible after transplantation and is not a contraindication for transplantation 1.
• The diagnosis of hepatopulmonary syndrome in children is confirmed by the presence of hypoxia and one of the following demonstrating the presence of intrapulmonary vascular dilatations: contrast-enhanced transthoracic echocardiography, technetium-labeled macro-aggregated albumin lung perfusion scan, or cardiac catheterization 1.
• The median survival in the absence of liver transplantation in adults with severe hepatopulmonary syndrome is less than 12 months, but is unknown in children 1.

Diagnosis and Treatment

• Diagnosis involves measuring arterial blood gases, contrast echocardiography to detect right-to-left shunting, and pulmonary angiography in some cases 1.
• The definitive treatment for hepatopulmonary syndrome is liver transplantation, as it can reverse the pulmonary vascular abnormalities 1.
• Supplemental oxygen is used to manage symptoms while awaiting transplant 1.
• The condition develops in approximately 10-30% of patients with cirrhosis and significantly increases mortality risk if left untreated 1.

From the Research

Definition and Characteristics of Hepatopulmonary Syndrome

• Hepatopulmonary syndrome (HPS) is a unique form of hypoxemia found in patients with chronic liver disease 2.
• It is characterized by intrapulmonary vascular dilatations and shunts, resulting in impaired gas exchange 3.
• HPS is defined by the presence of a triad of liver disease with intrapulmonary vascular dilation that causes abnormal arterial gas exchange 4.
• The syndrome is seen in 5-32% of patients with cirrhosis and is associated with increased mortality 4, 5.

Pathogenesis and Clinical Features

• The pathogenesis of HPS involves a complex interaction between the liver, the gut, and the lungs, predominantly impacting pulmonary endothelial cells, immune cells, and respiratory epithelial cells 3.
• Pulmonary microvascular dilation and angiogenesis are two central pathogenic features that drive abnormal pulmonary gas exchange in HPS 4.
• Clinical features of HPS include dyspnea, and most patients are either asymptomatic or develop insidious onset of symptoms 5.

Diagnosis and Management

• Pulse oximetry is a useful screening test for HPS, which can guide subsequent use of arterial blood gases 5, 6.
• Contrast-enhanced transthoracic echocardiography, perfusion lung scanning, and pulmonary arteriography are diagnostic imaging modalities that identify the presence of intrapulmonary vascular abnormalities 5, 6.
• Liver transplantation is the only established treatment option for HPS, resulting in complete resolution or significant improvement in gas exchange in over 85% of patients 2, 3, 4, 5, 6.
• No effective medical therapies are currently available for HPS, and liver transplantation is the only therapeutic option that can reverse the syndrome 3, 4, 6.