Physiopathological, clinical and therapeutic aspects of hepatopulmonary syndrome

Patients with cirrhosis or portal hypertension may develop hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PPHT). HPS occurs in 25% of the subjects with chronic hepatopathy waiting for a liver transplantation. HPS is characterized by chronic hepatopathy and/or portal hypertension, increased P(A-a)O2 gradient (more than 20 mmHg) with hypoxemia and intrapulmonary vascular dilatations without a primary cardiovascular disease. Hypoxiemia is due to intrapulmonary arteriovenous shunts and to dilatation of microvessels in basal parts of the lung and of pleural vessels. In patients with cirrhosis an impaired cardiovascular function is frequent, often in a subclinical phase of the disease. Left ventricular systolic and diastolic dysfunction may develop a chronic hepatopathy and the relation between right ventricular and liver failure has been studied. During cirrhosis characteristic alterations of systemic hemodynamic can cause the hyperdynamic circulatory syndrome. Contrast enhanced 2D ECHO cardiography is the preferred screening test for intrapulmonary arteriovenous shunts. The aim of HPS therapy is to contrast intrapulmonary vasodilatation, increased portal flux and hyperdynamic syndrome. New therapeutical agents are fosfodiesterase inhibitors, ET-1 receptor antagonists and selective NOS inhibitors. However, medical treatment is not much effective in HPS and liver transplantation is considered the only therapeutical chance.

Pulmonary vascular complications in asymptomatic children with portal hypertension

OBJECTIVES

: To determine the prevalence of portopulmonary hypertension, hepatopulmonary syndrome (HPS), and intrapulmonary vascular shunting (IPVS) in children with clinically stable portal hypertension and to assess the value of vasoactive peptide levels, biochemical tests and clinical signs or symptoms to predict these conditions.

PATIENTS AND METHODS

: A prospective, cross-sectional analysis was conducted on 33 children, ages 4 to 17 years, with stable cirrhosis (n = 28) or extrahepatic portal hypertension (n = 5). The children were screened for IPVS and hypoxia with contrast-enhanced echocardiography (cECHO) and pulse oximetry, and screened for pulmonary hypertension with Doppler echocardiography. Chemistries, radiographs, physical examinations, and levels of vasoactive peptides were compared between subjects with IPVS and those with normal cECHO.

RESULTS

: No subject had pulmonary hypertension. Six (19%) had IPVS, all of which had intrahepatic causes of portal hypertension, and 1 of whom had HPS. Compared with subjects with normal cECHO, those with IPVS had biochemical evidence of more advanced liver disease and higher b-type natriuretic peptide levels.

CONCLUSIONS

: Prevalence of portopulmonary hypertension and HPS appear to be rare in clinically stable children with portal hypertension. Intrapulmonary vascular shunting was present in 19% of these patients. A novel finding of this study is the elevation of b-type natriuretic peptide in children with IPVS.

Pulmonary complications of cirrhosis

Advanced liver disease and portal hypertension produce various intrathoracic complications that involve the pleural space, the lung parenchyma, and the pulmonary circulation. Dyspnea and arterial hypoxemia are the most common symptoms and signs in patients with such complications. This article focuses on the diagnosis and management of hepatopulmonary syndrome, portopulmonary hypertension, and hepatic hydrothorax. All are pulmonary processes associated with end-stage liver disease that lead to significant morbidity and affect the quality of life of patients who are suffering from liver cirrhosis.

Hepatopulmonary syndrome: an update

Hepatopulmonary syndrome (HPS) is a clinical threesome composed of liver disease, intrapulmonary vascular dilatation (IPVD) and arterial gas abnormalities. Its occurrence has been described in up to 32% of cirrhotic candidates for liver transplantation. It also affects non-cirrhotic patients with portal hypertension. Its pathogenesis is not well defined, but an association of factors such as imbalance in the endothelin receptor response, pulmonary microvascular remodeling and genetic predisposition is thought to lead to IPVD. Diagnosis is based on imaging methods that identify these dilatations, such as contrast echocardiography or perfusion scintigraphy with 99mTc, as well as analysis of arterial gases to identify elevated alveolar-arterial differences in O2 or hypoxemia. There is no effective pharmacological treatment and complete resolution only occurs through liver transplantation. The importance of diagnosing HPS lies in prioritizing transplant candidates, since presence of HPS is associated with worse prognosis. The aim of this paper was to review the pathogenetic theories and current diagnostic criteria regarding HPS, and to critically analyze the prioritization of patients with HPS on the liver transplant waiting list. Searches were carried out in the Medline (Medical Literature Analysis and Retrieval System Online) via PubMed, Cochrane Library and Lilacs (Literatura Latino-Americana e do Caribe em Ciências da Saúde) databases for articles published between January 2002 and December 2007 involving adults and written either in English or in Portuguese, using the term hepatopulmonary syndrome. The studies of greatest relevance were included in the review, along with text books and articles cited in references that were obtained through the review.

[Hepatopulmonary syndrome characteristics in hepatic cirrhosis associated with COPD]

AIM

To evaluate specific features of hepatopulmonary syndrome (HPS) in patients with cirrhosis and cirrhosis associated with chronic obstructive pulmonary disease (COPD).

MATERIAL AND METHODS

We made a retrospective analysis of case histories of 75 patients with hepatic cirrhosis (HC) of different etiology. The patients were divided into two groups: 23 patients with HC and COPD (group 1); 52 patients with HC without COPD (group 2). The patients were examined with spirography, gasometry. Single-breath carbon monoxide diffusion capacity (Dlco), TCO and TCO/VA were estimated. Transthoracic contrast-enhanced echocardiography was conducted for detection of intrapulmonary bypass in AaDO2 > 15 mm Hg.

RESULTS

COPD stage I and II were diagnosed in 14 of 23 and 9 of 23 patients of group 1, respectively. TCO and TCO/VA had a trend to lowering in group 1 (p > 0.05). PaO2 was lower (p < 0.05) while AaDO2 was higher (p < 0.05) in group 1. Four patients of group I had intrapulmonary bypasses: of the first degree (2 patients with hypoxemia) and of the first and second degree (2 patients with normoxemia). In group 2 three patients had intrapulmonary bypasses: of the fourth degree in 1 patient with hypoxemia and of the first and second degree in 2 patients with normoxemia.

CONCLUSION

HC patients with COPD had more severe hypoxemia. Mild and moderate HPS were registered in both groups. In COPD the risk of HPS is 3 times higher.

Hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is defined as clinical triad of advanced liver disease, arterial deoxygenation and intra pulmonary vascular dilatation. It is a rare complication of liver disease of varied etiology and indicates a poor prognosis. Many theories have been put forward to throw light over its pathogenesis. The major clinical manifestations are arterial hypoxemia, clubbed fingers and spider navei. Orthodeoxia and platypnea are usual clinical features. A simple non invasive method to screen HPS is desirable. Contrast enhanced 2D ECHO cardiography is the preferred screening test. No effective medical treatment has been found. Although liver transplant seems feasible to reverse (at least partially) this situation, however it is associated with increased post operative morbidity and mortality.

Current concepts in the management of hepatopulmonary syndrome

The hepatopulmonary syndrome is characterized as the triad of liver disease, pulmonary gas exchange abnormalities leading to arterial deoxygenation and evidence of intrapulmonary vascular dilatations. This review summarizes the pathological mechanisms leading to pulmonary vascular changes in hepatopulmonary syndrome. The role of the three currently used diagnostic imaging modalities of contrast-enhanced echocardiography, perfusion lung scanning and pulmonary arteriography that identify the presence of intrapulmonary vascular abnormalities are reviewed. Liver transplantation is considered to be the definitive treatment of hepatopulmonary syndrome with often successful reversal of hypoxemia, however other treatments have been trialed. This review further appraises the evidence for the use of pharmacological agents and the role of radiological interventions in hepatopulmonary syndrome.

Hepatopulmonary syndrome - past to present

Hepatopulmonary syndrome (HPS) is the one of the complication of liver cirrhosis with portal hypertension, irrespective of etiology, age and sex. It has also been observed in non cirrhotic portal hypertension and in acute hepatic conditions. Presence of hypoxemia or abnormal alveolar arterial oxygen tension with intrapulmonary vasodilation in liver cirrhosis is termed as HPS. Contrast echocardiogram is the better screening tool to demonstrate intrapulmonary shunt. Clinicians should be aware of other common chronic pulmonary and cardiac comorbid conditions, in particular COPD, tuberculosis, bronchial asthma and idiopathic pulmonary fibrosis, etc. which may coexist with HPS. There is no specific clinical finding to diagnose but digital clubbing, cyanosis, dyspnoea, platypnoea, and spider naevi are more common among cirrhosis with HPS. The presence of HPS independently worsens prognosis of cirrhosis. Even though number of mechanisms have been proposed to explain arterial hypoxemia in HPS, role of nitric oxide is the major one along with cytokines. Liver transplantation is the choice of treatment though mortality is comparatively high. There is no still effective recommended medical therapy to reverse this condition and anti cytokine/ nitric oxide inhibitors, etc are under preliminary stage.

Peri-operative respiratory failure in a cirrhotic patient: a misleading diagnosis

Patients with chronic liver disease may present with different degrees of respiratory dysfunction whose differential diagnosis is important before elective surgery. We report the case of a misleading diagnosis of peri-operative respiratory failure in a cirrhotic patient who underwent mastectomy. Intra-operative respiratory failure was ascribed by the anaesthetic team to pulmonary embolism and after the operation this diagnosis was still suspected. Despite postoperative heparin treatment, pulmonary gas exchange remained severely impaired. On the hypothesis of a right to left shunt, we performed transoesophageal echocardiography with a bubble test and confirmed hepatopulmonary syndrome. We administered anticoagulant therapy to the patient following surgery, increasing the risk of haemorrhage. We also continued orotracheal intubation and mechanical ventilation longer than was needed. Respiratory symptoms in a patient with liver disease should not be underestimated and up to 20% of these patients may have hepatopulmonary syndrome.

Respiratory dysfunction and pulmonary disease in cirrhosis and other hepatic disorders

End-stage liver disease and its complications are a leading cause of death among adults in the United States, and thousands of patients await liver transplantation. The liver plays a central role in health and homeostasis and thus the diseased liver leads to many deleterious effects on multiple organ systems, including the pulmonary system. We review the general effects of cirrhosis on the respiratory system, including mild hypoxemia, atelectasis, and hepatic hydrothorax. Cirrhosis is associated with 2 unique entities that affect the pulmonary vasculature: hepatopulmonary syndrome and portopulmonary hypertension. Hepatopulmonary syndrome, which is found in approximately 20% of patients awaiting liver transplantation, refers to the triad of hepatic dysfunction, hypoxemia, and intrapulmonary vascular dilations, and responds well to liver transplantation. In portopulmonary hypertension, cirrhosis and portal hypertension lead to pulmonary arterial hypertension, and portopulmonary hypertension has been considered a contraindication for transplantation. Currently, patients must have mild to moderate pulmonary hypertension to be considered for transplantation, and may still require long-term therapy with vasodilators to prevent right-ventricular failure and, consequently, failure of the newly transplanted liver allograft.

[Pulmonary complications of hepatic cirrhosis: portopulmonary hypertension and hepatopulmonary syndrome. The paradox of pulmonary vasoconstriction and vasodilation]

Cardiopulmonar complications in chronic liver diseases were described 100 years ago. Altough both hepatopulmonary sindrome and portopulmonary hypertension originates from liver damage, clinical findings and diagnosis are very different. These complications are important due to the highly deleterous impact on disease evolution and prognosis. Currently, there is not an ideal treatment for these diseases and liver transplantation should be adequately evaluated. In this review we analyze the most important issues on hepatopulmonary sindrome and portopulmonary hypertension. These complications,under the cornerstone of portal hypertension are characterized by pulmonary constriction and dilatation, respectively.

Hepatopulmonary syndrome following portopulmonary hypertension

Portopulmonary hypertension (PPHTN) and hepatopulmonary syndrome (HPS) are distinct clinical entities that may accompany liver disease. While PPHTN and HPS have been infrequently described as occurring in the same patient, to the present authors' knowledge, the order of occurrence has always been the initial onset of HPS, with pulmonary hypertension developing either concurrently or subsequently. In some instances, liver transplantation has been undertaken for HPS, followed by resolution of the HPS and subsequent development of pulmonary hypertension. The current case study presents a patient with hepatitis C-related cirrhosis in whom PPTHN developed initially, followed 2 yrs later by the development of the HPS. The current authors speculate that progressive imbalance in favour of endogenous vasodilators over vasoconstrictive factors led to normalisation of the pulmonary artery pressures.

Utility of pulse oximetry screening for hepatopulmonary syndrome

BACKGROUND & AIMS

Hepatopulmonary syndrome is characterized by oxygenation abnormalities caused by intrapulmonary vasodilatation in the setting of liver disease and/or portal hypertension. This syndrome occurs in approximately 15%-30% of cirrhotic patients and influences mortality and transplant candidacy. However, no specific screening guidelines are established. We evaluated pulse oximetry with contrast echocardiography in detecting hepatopulmonary syndrome in a cohort of patients undergoing evaluation for liver transplantation.

METHODS

One hundred twenty-seven consecutive patients referred for liver transplantation evaluation were prospectively enrolled and underwent pulse oximetry, contrast echocardiography, and arterial blood gas measurements on room air. Demographic, clinical, and laboratory data were recorded and analyzed.

RESULTS

Forty-one (32%) patients were found to have hepatopulmonary syndrome. There were no significant differences in demographic or clinical features compared with patients without hepatopulmonary syndrome, with the exception of pulse oximetry and oxygenation abnormalities. With a threshold value of <96%, pulse oximetry had a sensitivity and specificity of 100% and 88%, respectively, for detecting patients with a partial pressure of oxygen <60 mm Hg. Receiver operator characteristic analysis revealed that a pulse oximetry value of < or =94% detected all patients with a partial pressure of oxygen <60 mm Hg with an increased specificity of 93%. In addition, higher pulse oximetry thresholds reliably identified HPS patients with less severe hypoxemia, albeit with lower specificity.

CONCLUSIONS

Pulse oximetry is a simple, low cost, and widely available technique that reliably predicts the presence and severity of hypoxemia in patients with hepatopulmonary syndrome. Institution of pulse oximetry screening might enhance detection and improve management of hepatopulmonary syndrome in cirrhosis.

Clinical controversies surrounding the diagnosis and treatment of hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is a clinical syndrome which complicates liver disease but remains poorly defined. To date there is no consensus on the definition of hypoxemia or the best diagnostic test that provides evidence of intrapulmonary shunting. Furthermore, it is reasonable to question whether the role of intrapulmonary shunting has been overplayed in the etiology of HPS and if echocardiographic intrapulmonary shunts could simply be nonspecific markers of the hyperdynamic circulation of liver disease. These inquiries lend support to theories that HPS is primarily a manifestation of profound pulmonary vascular autoregulatory failure that occurs in predisposed patients. Because there is little experience with clinical interventions for HPS other than liver transplantation, there are few accepted, efficacious therapeutic options for these patients. Because liver transplantation remains the only treatment known to effectively ''treat'' HPS, many medical communities have increased the priority of HPS patients over others who are waiting for life saving organs. Until there is further evidence that effectively identifies patients with HPS and that predicts outcomes, the preferential allocation of organs to patients with suspected HPS may unjustly cause the death of others waiting for transplantation.

Hepatopulmonary syndrome

This is a report of a 56-year-old male who was admitted to the Intensive Care Unit of the San Juan V.A. Medical Center with altered mental status and severe hypoxemia. He was diagnosed with severe hyponatremia and hepatopulmonary syndrome.

Portopulmonary hypertension

As a result of the success of orthotopic liver transplantation, there has been increasing interest in the diagnosis and therapeutic options for the pulmonary vascular complications of hepatic disease. These pulmonary vascular complications range from the hepatopulmonary syndrome, which is characterized by intrapulmonary vascular dilatations, to portopulmonary hypertension (POPH), which is characterized by an elevated pulmonary vascular resistance as a consequence of obstruction to pulmonary arterial blood flow. This review concentrates on POPH.

Deleterious effect of nitric oxide inhibition in chronic hepatopulmonary syndrome

On the basis of limited experimental and clinical studies, increased activity of the vasodilatory nitric oxide-cyclic guanosine monophosphate pathway is considered to play a key role in the pathogenesis of hepatopulmonary syndrome. We report a 46-year-old woman with Child-Pugh class C cirrhosis and progressive dyspnoea for 12 months. Investigations revealed elevated circulating concentrations of nitric oxide metabolites and exhaled nitric oxide levels, an hyperdynamic circulation with low systemic vascular resistance and mean arterial pressure, a large right to left intrapulmonary shunt fraction on radiolabelled macroaggregated albumin perfusion scanning, positive contrast-enhanced echocardiography, reduced diffusion capacity of carbon monoxide, hypoxaemia and orthodeoxyia, all in keeping with severe hepatopulmonary syndrome. Sequential inhibition of the nitric oxide-cyclic guanosine monophosphate pathway using curcumin (diferuloylmethane), terlipressin and methylene blue was associated with substantial improvements in vascular tone and the hyperdynamic circulation. No improvement, however, in the intrapulmonary shunt was demonstrated. Both hypoxaemia and orthodeoxia were substantially, reproducibly and reversibly worsened with all three treatments. Our findings argue against the contention that intrapulmonary shunting and impairment in arterial oxygenation in hepatopulmonary syndrome are necessarily the consequence of on-going, nitric oxide-cyclic guanosine monophosphate-mediated vasodilatation, at least in the chronic stage, and, given the possibility of substantial worsening of pulmonary oxygen exchange, suggest that inhibition of the nitric oxide-cyclic guanosine monophosphate pathway should be avoided in this setting.

Hepatopulmonary syndrome and portopulmonary hypertension: what's new?

Hepatopulmonary syndrome (HPS) is found in 4-47% of patients with cirrhosis and is characterized by intrapulmonary vascular dilatations especially in the basal parts of the lung. Liver injury and/or portal hypertension trigger the release of endothelin-l, TNF-alpha, cytokines and mediate vascular shear stress and release of nitric oxide and carbon monoxide, all contributing to intrapulmonary vasodilation. Severe HPS increases mortality (30%) after liver transplantation, especially if Pa O2 is below 50 mmHg. The diagnosis is made by calculating the alveolar-arterial oxygen gradient and by performing a contrast echocardiography. Medical therapy fails and the only long-term treatment available is liver transplantation. More than 85% experience significant improvement or complete resolution in hypoxaemia, but this may take more than 1 year. Portopulmonary hypertension (PPHT) occurs in 2-8% of the patients with cirrhosis. Imbalance between vasodilating (decreased pulmonary expression of eNOS and prostacyclin I2) and vasoconstrictive agents (increased expression of ET-1 and angiotensin 1) may be responsible for misguided angiogenesis and pulmonary hypertension. The diagnosis is made by performing an echocardiography and a right heart catheterisation when systolic pulmonary artery pressure is higher than 30 mmHg on echocardiography. Although prostacyclin analogues are efficacious, adverse effects in terms of safety, tolerability and drug delivery occur. Bosentan is probably the therapy of choice for patients with PPHT because it decreases pulmonary but can also diminish portal hypertension. Sildenafil, a phosphodiesterase-5 inhibitor is used for idiopathic pulmonary hypertension, however, it should be used cautiously in patients with portal hypertension as it may increase portal hypertension by splanchnic vasodilation.