Hepatopulmonary syndrome: What we know and what we would like to know

Abstract

Hepatopulmonary syndrome (HPS) is characterized by abnormalities in blood oxygenation caused by the presence of intrapulmonary vascular dilations (IPVD) in the context of liver disease, generally at a cirrhotic stage. Knowledge about the subject is still only partial. The majority of the information about the etiopathogenesis of HPS has been obtained through experiments on animals. Reported prevalence in patients who are candidates for a liver transplantation (LT) varies between 4% and 32%, with a predominance of mild or moderate cases. Although it is generally asymptomatic it does have an impact on their quality of life and survival. The diagnosis requires taking an arterial blood gas sample of a seated patient with alveolar-arterial oxygen gradient (AaO2) ≥ 15 mm Hg, or ≥ 20 mm Hg in those over 64 years of age. The IPVD are identified through a transthoracic contrast echocardiography or a macroaggregated albumin lung perfusion scan ((99m)Tc-MAA). There is currently no effective medical treatment. LT has been shown to reverse the syndrome and improve survival rates, even in severe cases. Therefore the policy of prioritizing LT would appear to increase survival rates. This paper takes a critical and clinical look at the current understanding of HPS, as well as the controversies surrounding it and possible future research.

Pulmonary Complications of Liver Cirrhosis: A Concise Review

“…The most challenging post LT is severe hypoxemia post-operative period with prolonged respiratory weaning that often resulted in death. Ten-year survival after LT in HPS patients stands at 64% [10] and post LT mortality rates obtained in these studies range between 7.7 and 33% [10].…”

“…Angiogenesis is also considered to be an important phenomenon in the development of HPS [10] through upregulation of the vascular endothelial growth factor. Other mechanism suggested from experimental studies was vasodilation via increased carbon monoxide production through haem oxygenase [7].…”

“…Patients who experience severe dyspnea at rest and evidence of hypoxemia clinically should receive oxygen therapy [10]. Many studies have looked into treatment of HPS with nitric oxide inhalation, low consumption of L-arginine using methylene blue, aspirin, antibiotic usage to reduce intestine's bacterial translocation, somatostatin, indomethacin, garlic, and transjugular intrahepatic portosystemic shunt (TIPS), but none of them have not shown any particular benefit as long-term treatment of HPS [7].…”

Correlations of MMP‐2 and MMP‐9 gene polymorphisms with the risk of hepatopulmonary syndrome in cirrhotic patients: A case‐control study

“…Cirrhosis is commonly accompanied by portal hypertension along with systemic and splanchnic arterial vasodilation, as well as central hypovolemia [1]. Hepatopulmonary syndrome (HPS) is characterized by vasodilatation and portopulmonary hypertension which results from vasoconstriction [2,3]. It was well‐acknowledged as a significant vascular complication in lungs because of systemic hypoxemia in patients with portal hypertension and cirrhosis [4].…”

Liver in the Chinese and Western Medicine

“…A large amount of studies suggest that the liver in TCM should be related to the nerve-endocrine-immune network and that it governs the qi-blood activities via the nerves and endocrine [10], which is similar to Western medicine, according to which the liver regulates the whole body through metabolic function. For example, in TCM, the liver regulates the qi activities, similar to homeostasis emphasized by modern medicine; in TCM, the liver modulates emotions, which are considered to be closely related to the central neurotransmitters in modern medicine [11,12,13,14,15]; the liver governs dispersion and dredging, which conforms to the digestion and absorption theory in the Western medicine; in TCM, the liver maintains the normal qi activities, which is essential for the blood circulation [15,16]; the dispersion and dredging function of the TCM liver is also closely associated with the water metabolism and reproductive function [17,18]. …”