Hepatopulmonary syndrome

Hepatopulmonary Syndrome: A Comprehensive Review

Hepatopulmonary syndrome (HPS) is defined by abnormally dilated blood vessels and shunts within the lungs, leading to impaired oxygen exchange. This condition results from intricate interactions between the liver, the gastrointestinal system, and the lungs. This complex system primarily affects pulmonary endothelial, immunomodulatory, and respiratory epithelial cells. Consequently, this contributes to pathological pulmonary changes characteristic of HPS. A classification system based on the severity of oxygen deficiency has been proposed for grading the physiological dysfunction of HPS. Contrast-enhanced echocardiography is considered the primary radiological evaluation for identifying abnormal blood vessel dilations within the lungs, which, combined with an elevated alveolar-arterial gradient, is essential for making the diagnosis. Liver transplantation is the sole effective definitive treatment that can reverse the course of the condition. Despite often being symptomless, HPS carries a significant risk of mortality before transplantation, regardless of the severity of liver disease. Meanwhile, there is varying data regarding survival rates following liver transplantation. The adoption of the model for end-stage liver disease (MELD) standard exception policy has notably improved the results for individuals with HPS compared to the period before MELD was introduced. This review offers a summary of the present understanding, highlighting recent advancements in the diagnosis and treatment of HPS. Furthermore, it aims to augment comprehension of the condition's fundamental mechanisms through insights derived from experimental models and translational research.

Managing portal hypertension in patients with liver cirrhosis

Portal hypertension is one cause and a part of a dynamic process triggered by chronic liver disease, mostly induced by alcohol or incorrect nutrition and less often by viral infections and autoimmune or genetic disease. Adequate staging - continuously modified by current knowledge - should guide the prevention and treatment of portal hypertension with defined endpoints. The main goals are interruption of etiology and prevention of complications followed, if necessary, by treatment of these. For the past few decades, shunts, mostly as intrahepatic stent bypass between portal and hepatic vein branches, have played an important role in the prevention of recurrent bleeding and ascites formation, although their impact on survival remains ambiguous. Systemic drugs, such as non-selective beta-blockers, statins, or antibiotics, reduce portal hypertension by decreasing intrahepatic resistance or portal tributary blood flow or by blunting inflammatory stimuli inside and outside the liver. Here, the interactions among the gut, liver, and brain are increasingly examined for new therapeutic options. There is no general panacea. The interruption of initiating factors is key. If not possible or if not possible in a timely manner, combined approaches should receive more attention before considering liver transplantation.

Improved severe hepatopulmonary syndrome after liver transplantation in an adolescent with end-stage liver disease secondary to biliary atresia

Hepatopulmonary syndrome (HPS) is a serious complication of end-stage liver disease, which is characterized by hypoxia, intrapulmonary vascular dilatation, and liver cirrhosis. Liver transplantation (LT) is the only curative treatment modality for patients with HPS. However, morbidity and mortality after LT, especially in cases of severe HPS, remain high. This case report describes a patient with typical findings of an extracardiac pulmonary arteriovenous shunt on contrast-enhanced transesophageal echocardiography (TEE), and clubbing fingers, who had complete correction of HPS by deceased donor LT. The patient was a 16-year-old female who was born with biliary atresia and underwent porto-enterostomy on the 55th day after birth. She had been suffered from progressive liver failure with dyspnea, clubbing fingers, and cyanosis. Preoperative arterial blood gas analysis revealed severe hypoxia (arterial O2 tension of 54.5 mmHg and O2 saturation of 84.2%). Contrast-enhanced TEE revealed an extracardiac right-to-left shunt, which suggested an intrapulmonary arteriovenous shunt. The patient recovered successfully after LT, not only with respect to physical parameters but also for pychosocial activity, including school performance, during the 30-month follow-up period.

Liver protection in the perioperative setting

With recent advances in surgical and anaesthetic management, clinical medicine has responded to societal expectations and the number of operations in patients with a high-risk of perioperative liver failure has increased over the last decades. This review will outline important pathophysiological alterations common in patients with pre-existing liver impairment and thus highlight the anaesthetic challenge to minimise perioperative liver insults. It will focus on the intraoperative balancing act to reduce blood loss while maintaining adequate liver perfusion, the various anaesthetic agents used and their specific effects on hepatic function, perfusion and toxicity. Furthermore, it will discuss advances in pharmacological and ischaemic preconditioning and summarise the results of recent clinical trials.

Long-term management of alcoholic liver disease

Despite the epidemics of viral hepatitis C and nonalcoholic fatty liver disease, alcohol remains one of the major causes of liver disease. Commonly, hepatitis C and other liver diseases are found in association with alcohol consumption. This association in many instances is noted to accelerate the progression of liver disease. In many respects, the long-term management of alcoholic liver disease is not dissimilar from the long-term management of patients with cirrhosis from other etiologies. One major element is the abstinence of alcohol use. The ability to maintain sobriety has a major impact on the outcome of patients with alcoholic cirrhosis because maintaining abstinence can lead to significant regression of fibrosis and possibly early cirrhosis. Similarities in managing patients with cirrhosis due to alcohol or cirrhosis from other causes include vaccination to prevent superimposed viral hepatitis and screening for esophageal varices and hepatocellular carcinoma with subsequent appropriate therapy.

Paroxetine for hepatopulmonary syndrome?

Hepatopulmonary syndrome (HPS) is a severe pulmonary sequela which can affect up to 15% of patients with cirrhotic liver disease. There is no treatment for HPS other than liver transplantation. The cause of HPS is incompletely understood, but the pulmonary vasodilation in HPS is thought to be related to increased levels of nitric oxide. We therefore suggest that, the extremely safe and commonly used antidepressant medication paroxetine (Paxil) which is a potent nitric oxide synthase (NOS) inhibitor be considered for use in HPS.

Abernethy malformation: one of the etiologies of hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is the clinical relationship between hepatic disease and the existence of pulmonary vascular dilatations, which can result in a range of arterial oxygenation abnormalities. It is probably caused by an alteration in the synthesis or metabolism of vasoactive pulmonary substances at a hepatic level, leading to vasodilatation of pulmonary vessels and diffusion perfusion defects. The Abernethy malformation is characterized by the congenital diversion of portal blood away from the liver, by either end-to-side or side-to-side shunt. Here, we report on a 5-year-and-11-month-old-boy who had started cyanosis at age 4 years and 11 months, and did not have any other pulmonary or cardiac signs or symptoms. In the investigation, arterial blood gases revealed a PaO(2) of 41.4 mm Hg. The chest x-ray film and echo Doppler cardiography were normal. Nuclear scanning with Technetium 99m-labeled macroaggregated albumin showed the presence of arteriovenous shunt, at 47%. Abdominal echography revealed Abernethy malformation with an absence of portal vein. We concluded that the patient had HPS caused by Abernethy malformation. The possible mechanism is that in this malformation, there is a deviation in the blood that comes from the spleen to the vena cava without passing through the liver, so there is no metabolism of some substances which can be responsible for the imbalance between the vasodilatation and the vasoconstriction of the pulmonary circulation. Abernethy malformation must be included as one of the etiologies of hepatopulmonary syndrome. This is the first case described in the literature with this form of presentation.

Retrospective analysis of the results of liver transplantation for adults with severe hepatopulmonary syndrome

The hepatopulmonary syndrome (HPS), consisting of elevated alveolar-arterial oxygen gradient and intrapulmonary vascular abnormalities in the presence of advanced liver disease, is associated with high mortality. Liver transplantation (LT) has been used for the treatment of HPS; however, the success of LT for the treatment of HPS is not uniformly documented. We reviewed our experience over a 5-year period and identified eight adult patients with incapacitating respiratory symptoms compatible with HPS. Inclusion criteria included hypoxemia, normal lung volumes, reduced oxygen diffusing capacity (D(L)CO), and the presence of intrapulmonary shunting. Underlying liver disease was caused by hepatitis C (2 patients), primary biliary cirrhosis (1 patient), cryptogenic cirrhosis (1 patient), alcohol (2 patients), and hepatitis C with alcohol (2 patients). Six out of eight patients required preoperative oxygen support. Severe hypoxemia was present in seven patients (Pa(O2) 51.5 +/- 8.2 mm Hg). Three patients had complicating pulmonary hypertension. All patients exhibited a severely reduced D(L)CO (44.6 +/- 12.2% of predicted value). Six patients were transplanted, with five requiring oxygen support at the time of discharge. Resolution of oxygen dependency occurred in all patients but was delayed in the two patients exhibiting complicating pulmonary hypertension (288.5 +/- 37.4 v 53.5 +/- 35.7 days). All patients exhibited O2 saturations greater than 98% on room air. Currently, three patients are alive and off oxygen. The current report documents successful resolution of hypoxemia after LT in this pilot cohort. This supports the newly implemented United Network for Organ Sharing (UNOS) criteria, that LT for HPS may be extended to include patients with Pa(O2) < 60 mm Hg.

Regulation of heme oxygenase-1 by nitric oxide during hepatopulmonary syndrome

During hepatopulmonary syndrome caused by liver cirrhosis, pulmonary endothelial nitric oxide (NO) synthase (NOS) expression and NO production are increased. Increased NO contributes to the blunted hypoxic pressor response (HPR) during cirrhosis and may induce heme oxygenase-1 (HO-1) expression and carbon monoxide (CO) production, exacerbating the blunted HPR. We hypothesized that NO regulates the expression of HO-1 during cirrhosis, contributing to hepatopulmonary syndrome. Cirrhosis was induced in rats by common bile duct ligation (CBDL). Rats were studied 2 and 5 wk after CBDL or sham surgery. Lung HO-1 expression was elevated 5 wk after CBDL. Liver HO-1 was increased at 2 wk and remained elevated at 5 wk. In catheterized rats, the blunted HPR was partially restored by HO inhibition. Rats treated with the NOS inhibitor N(G)-nitro-L-arginine methyl ester for the entire 2- or 5-wk duration had normalized HO-1 expression and HPR. These data provide in vivo evidence for the NO-mediated upregulation of HO-1 expression and support the concept that hepatopulmonary syndrome is multifactorial, involving not only NO, but also HO-1 and CO.