Purpose of review:
To discuss the advances in the understanding of the pathophysiology of experimental and human hepatopulmonary syndrome (HPS) and in the management of HPS, particularly regarding liver transplantation.
Advances have been made in defining the pathophysiology of HPS in experimental models as well as in human disease, including the role of endothelin-1, pulmonary monocytes, and angiogenesis. Additionally, the implications of the presence of HPS as it relates to prioritizing patients for liver transplantation and posttransplant outcomes will also be reviewed.
Mechanisms of disease continue to be defined in HPS, providing potential targets for pharmacologic intervention. Outcomes after liver transplantation are also becoming clearer, including the management of HPS with severe hypoxemia.
"It has been established that elevated and very low capillary pressures increase lung impedance and modify alveolar architecture and mechanical properties (Silva et al., 2010; West, 2000). The association between high intrapulmonary vascular flow and low pulmonary vascular resistance is well established in the literature on HPS respiratory pathophysiology (Palma and Fallon, 2006). However, its impact on pulmonary mechanical properties and on lung tissue structure as well as composition requires further elucidation. "
[Show abstract][Hide abstract] ABSTRACT: Intrapulmonary vasodilation is a hallmark of the hepatopulmonary syndrome (HPS). However, its effects on respiratory mechanical properties and lung morphology are unknown. To determine these effects, 28 rats were randomly divided to control and experimental HPS groups (eHPS). The spontaneous breathing pattern, gas exchange, respiratory system mechanical properties, and lung and liver morphology of the rats were evaluated. Tidal volume, minute ventilation and mean inspiratory flow were significantly reduced in the eHPS group. Chest wall pressure dissipation against the resistive and viscoelastic components and elastic elastance were increased in the eHPS group. The lung resistive pressure dissipation was lower but the viscoelastic pressure was higher in the eHPS group. The airway volume proportion of collagen and elastic fibers was increased in the eHPS animals (16% and 51.7%; P<0.05 and P<0.001, respectively). The proportion of collagen volume in the vasculature increased 29% in the eHPS animals (P<0.01). HPS presents with respiratory system mechanical disarray as well as airway and vascular remodeling.
"Number of mechanisms have been described in literature. The major mediator of pulmonary vascular abnormality is nitric oxide (NO) a vasodilator molecule guanylyl cyclase in vascular smooth muscle  . There is failure of the diseased liver to clear the pulmonary vasodilators. "
[Show abstract][Hide abstract] ABSTRACT: Advanced portal hypertension accompanying end-stage liver disease results in an altered milieu due to inadequate detoxification of blood from splanchnic circulation by the failing liver. The portosystemic shunts with hepatic dysfunction result in an increased absorption and impaired neutralisation of the gastrointestinal bacteria and endotoxins leads to altered homeostasis with multiorgan dysfunction. The important cardiopulmonary complications are cirrhotic cardiomyopathy, hepatopulmonary syndrome, portopulmonary hypertension, and right-sided hydrothorax.
"Platypnea and orthodexia are classically presented; they are highly specific signs for HPS in the setting of liver cirrhosis, and they are the result of a gravitational increase in blood flow through the dilated vessels in the lung bases. Cough, clubbing and distal cyanosis can also be associated with HPS (3). "
[Show abstract][Hide abstract] ABSTRACT: Although liver transplantation (LT) is the only effective treatment option for hepatopulmonary syndrome (HPS), the post-LT morbidity and mortality have been high for patients with severe HPS. We performed post-LT embolotherapy in a 10-year-old boy who had severe type I HPS preoperatively, but he failed to recover early from his hypoxemic symptoms after an LT. Multiple embolizations were then successfully performed on the major branches that formed the abnormal vascular structures. After the embolotherapy, the patient had symptomatic improvement and he was discharged without complications.
Korean journal of radiology: official journal of the Korean Radiological Society 06/2010; 11(4):485-9. DOI:10.3348/kjr.2010.11.4.485 · 1.57 Impact Factor
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