Hepatopulmonary syndrome overview: Difference between revisions
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==Pathophysiology== | ==Pathophysiology== | ||
The exact pathogenesis of hepatopulmonary syndrome is not fully understood. Pulmonary microvascular dilation and angiogenesis are two central pathogenic features that drive abnormal pulmonary gas exchange in experimental hepatopulmonary syndrome, and thus might underlie hepatopulmonary syndrome in humans. It is thought that hepatopulmonary syndrome is the result of microscopic intrapulmonary arteriovenous dilatations due to either increased liver production or decreased the liver clearance of [[Vasodilator|vasodilators]], possibly involving [[nitric oxide]]. The progression to hepatopulmonary syndrome is believed that involves the [[Nitric oxide|nitric oxid]]<nowiki/>e [[metabolism]]. The dilation of these blood vessels causes overperfusion relative to ventilation, leading to [[ventilation-perfusion mismatch]] and [[hypoxemia]]. There is an increased gradient between the partial pressure of [[oxygen]] in the alveoli of the lung and adjacent arteries (alveolar-arterial [A-a] gradient) while breathing room air. Patients with hepatopulmonary syndrome have [[platypnea]]-orthodeoxia [[syndrome]] (POS); that is, because intrapulmonary vascular dilations (IPVDs) predominate in the bases of the [[Lung|lungs]], standing worsens [[hypoxemia]] (orthodeoxia)/dyspnea (platypnea) and the [[supine position]] improves [[oxygenation]] as blood is redistributed from the bases to the apices. Additionally, late in [[cirrhosis]], it is common to develop [[high output failure]], which would lead to less time in [[Capillary|capillaries]] per [[red blood cell]], exacerbating the [[hypoxemia]]. As discussed below a variety of angiogenesis-related genes polymorphism has been linked to hepatopulmonary syndrome. Increased levels of endothelin-1 in cirrhotic patients have been correlated with intrapulmonary molecular and gas exchange abnormalities, hypothesizing a probable contribution to the pathogenesis of hepatopulmonary syndrome. | |||
==Causes== | ==Causes== | ||
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==Differentiating Hepatopulmonary Syndrome from Other Diseases== | ==Differentiating Hepatopulmonary Syndrome from Other Diseases== | ||
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==Epidemiology and Demographics== | ==Epidemiology and Demographics== | ||
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==Risk Factors== | ==Risk Factors== | ||
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==Screening== | ==Screening== | ||
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==Natural History, Complications, and Prognosis== | ==Natural History, Complications, and Prognosis== | ||
Revision as of 17:27, 6 September 2019
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Hepatopulmonary syndrome Microchapters |
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Differentiating Hepatopulmonary syndrome from other Diseases |
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Diagnosis |
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Treatment |
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Hepatopulmonary syndrome overview On the Web |
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American Roentgen Ray Society Images of Hepatopulmonary syndrome overview |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Soroush Seifirad, M.D.[2]
Overview
Historical Perspective
In 1884, Flückiger was the first to report the association between liver dysfunction and the development of hypoxemia. (Flückiger M. Vorkommen von trommelschlagel-formigen fingerendphalangen ohne chronische veranderungeng an den lungen oder am herzen. Wien Med Wochenschr. 1884;34:1457.) The term "hepatopulmonary syndrome" was first suggested by Kennedy and Knudson almost 100 years later,in 1977 during describing a patient with the classic findings of hepatopulmonary syndrome.
Classification
There is no established system for the classification of hepatopulmonary syndrome. Nevertheless, HPS can be classified in term of severity based on atrial blood gas analysis.
Pathophysiology
The exact pathogenesis of hepatopulmonary syndrome is not fully understood. Pulmonary microvascular dilation and angiogenesis are two central pathogenic features that drive abnormal pulmonary gas exchange in experimental hepatopulmonary syndrome, and thus might underlie hepatopulmonary syndrome in humans. It is thought that hepatopulmonary syndrome is the result of microscopic intrapulmonary arteriovenous dilatations due to either increased liver production or decreased the liver clearance of vasodilators, possibly involving nitric oxide. The progression to hepatopulmonary syndrome is believed that involves the nitric oxide metabolism. The dilation of these blood vessels causes overperfusion relative to ventilation, leading to ventilation-perfusion mismatch and hypoxemia. There is an increased gradient between the partial pressure of oxygen in the alveoli of the lung and adjacent arteries (alveolar-arterial [A-a] gradient) while breathing room air. Patients with hepatopulmonary syndrome have platypnea-orthodeoxia syndrome (POS); that is, because intrapulmonary vascular dilations (IPVDs) predominate in the bases of the lungs, standing worsens hypoxemia (orthodeoxia)/dyspnea (platypnea) and the supine position improves oxygenation as blood is redistributed from the bases to the apices. Additionally, late in cirrhosis, it is common to develop high output failure, which would lead to less time in capillaries per red blood cell, exacerbating the hypoxemia. As discussed below a variety of angiogenesis-related genes polymorphism has been linked to hepatopulmonary syndrome. Increased levels of endothelin-1 in cirrhotic patients have been correlated with intrapulmonary molecular and gas exchange abnormalities, hypothesizing a probable contribution to the pathogenesis of hepatopulmonary syndrome.
Causes
Differentiating Hepatopulmonary Syndrome from Other Diseases
Epidemiology and Demographics
Risk Factors
Screening