Intrapulmonary vascular dilatations are common in portopulmonary hypertension and may be associated with decreased survival

Disrupted BMP-9 Signaling Impairs Pulmonary Vascular Integrity in Hepatopulmonary Syndrome

Rationale: Hepatopulmonary syndrome (HPS) is a severe complication of liver diseases characterized by abnormal dilation of pulmonary vessels, resulting in impaired oxygenation. Recent research highlights the pivotal role of liver-produced BMP-9 (bone morphogenetic protein-9) in maintaining pulmonary vascular integrity. Objectives: This study aimed to investigate the involvement of BMP-9 in human and experimental HPS. Methods: Circulating BMP-9 levels were measured in 63 healthy control subjects and 203 patients with cirrhosis with or without HPS. Two animal models of portal hypertension were employed: common bile duct ligation with cirrhosis and long-term partial portal vein ligation without cirrhosis. Additionally, the therapeutic effect of low-dose BMP activator FK506 was investigated, and the pulmonary vascular phenotype of BMP-9-knockout rats was analyzed. Measurements and Main Results: Patients with HPS related to compensated cirrhosis exhibited lower levels of circulating BMP-9 compared with patients without HPS. Patients with severe cirrhosis exhibited consistently low levels of BMP-9. HPS characteristics were observed in animal models, including intrapulmonary vascular dilations and an increase in the alveolar-arterial gradient. HPS development in both rat models correlated with reduced intrahepatic BMP-9 expression, decreased circulating BMP-9 level and activity, and impaired pulmonary BMP-9 endothelial pathway. Daily treatment with FK506 for 2 weeks restored the BMP pathway in the lungs, alleviating intrapulmonary vascular dilations and improving gas exchange impairment. Furthermore, BMP-9-knockout rats displayed a pulmonary HPS phenotype, supporting its role in disease progression. Conclusions: The study findings suggest that portal hypertension-induced loss of BMP-9 signaling contributes to HPS development.

Portopulmonary Hypertension: Management and Liver Transplantation Evaluation

Portopulmonary hypertension (POPH) affects 5% to 6% of patients with advanced liver disease and accounts for 5% to 15% of pulmonary arterial hypertension (PAH) cases. Compared with idiopathic PAH, POPH is associated with significantly worse survival. Recent studies have improved our understanding of the role of both PAH therapy and liver transplantation (LT) in the management of POPH and their impact on overall prognosis. We performed a review of the published literature to summarize the available evidence and guidelines regarding the diagnosis and management of POPH. POPH is defined by the presence of precapillary PH in the context of portal hypertension. POPH is associated with increased perioperative risk at the time of LT, which can be stratified by mean pulmonary arterial pressure and pulmonary vascular resistance. Screening with echocardiography is recommended in all LT candidates to facilitate detection and treatment of POPH. Despite a paucity of evidence, POPH is treated similarly to idiopathic PAH with PAH therapy. These therapies are associated with improved pulmonary hemodynamics and facilitation of safe LT. LT can result in improvement or resolution of POPH in half of patients and has been associated with improved survival in highly selected patients. The prognosis in POPH is poor and is impacted by the severity of both PH and liver disease. Management with a combination of PAH therapy and LT in selected patients has been associated with improved pulmonary hemodynamics and survival.

Emerging Evidence on Coronary Heart Disease Screening in Kidney and Liver Transplantation Candidates: A Scientific Statement From the American Heart Association: Endorsed by the American Society of Transplantation

Coronary heart disease is an important source of mortality and morbidity among kidney transplantation and liver transplantation candidates and recipients and is driven by traditional and nontraditional risk factors related to end-stage organ disease. In this scientific statement, we review evidence from the past decade related to coronary heart disease screening and management for kidney and liver transplantation candidates. Coronary heart disease screening in asymptomatic kidney and liver transplantation candidates has not been demonstrated to improve outcomes but is common in practice. Risk stratification algorithms based on the presence or absence of clinical risk factors and physical performance have been proposed, but a high proportion of candidates still meet criteria for screening tests. We suggest new approaches to pretransplantation evaluation grounded on the presence or absence of known coronary heart disease and cardiac symptoms and emphasize multidisciplinary engagement, including involvement of a dedicated cardiologist. Noninvasive functional screening methods such as stress echocardiography and myocardial perfusion scintigraphy have limited accuracy, and newer noninvasive modalities, especially cardiac computed tomography-based tests, are promising alternatives. Emerging evidence such as results of the 2020 International Study of Comparative Health Effectiveness With Medical and Invasive Approaches-Chronic Kidney Disease trial emphasizes the vital importance of guideline-directed medical therapy in managing diagnosed coronary heart disease and further questions the value of revascularization among asymptomatic kidney transplantation candidates. Optimizing strategies to disseminate and implement best practices for medical management in the broader end-stage organ disease population should be prioritized to improve cardiovascular outcomes in these populations.

Diagnosis of Hepatopulmonary Syndrome in a Large Integrated Health System

BACKGROUND & AIMS

Data on the accuracy of the diagnosis of hepatopulmonary syndrome (HPS) in cirrhosis is limited. We evaluated the clinical characteristics of patients with International Classification of Diseases (ICD) codes for hepatopulmonary syndrome (HPS) in a large integrated health system.

METHODS

A retrospective review of encounters was performed of all patients with ICD-9-CM and/or ICD-10-CM diagnosis of cirrhosis and HPS from 2014-2019 in a multi-state health system. Demographics and cardiopulmonary testing closest to the time of HPS diagnosis were recorded. HPS was defined using standard criteria.

RESULTS

A total of 42,749 unique individuals with cirrhosis were identified. An ICD diagnosis of HPS was found in 194 patients (0.45%), of which 182 had clinically confirmed cirrhosis. 143 (78.5%) underwent contrast-enhanced transthoracic echocardiography, and 98 (54%) had delayed shunting. Among them, 61 patients had a documented arterial blood gas, with 53 showing abnormal oxygenation (A-a gradient of >15 mm Hg). 12 were excluded due to significant pulmonary function test abnormalities and abnormal oxygenation from other cardiopulmonary diseases. Ultimately, 41 (22.5%) fulfilled the criteria for HPS. When stratifying those with an ICD code diagnosis of HPS into HPS, no HPS and indeterminate HPS groups, based on standard diagnostic criteria for HPS, we found that the confirmed HPS patients had similar complications except for less portopulmonary hypertension, worse gas exchange, less cardiopulmonary disease and were more often diagnosed in transplant centers.

CONCLUSIONS

The diagnosis of HPS by ICD code is made in an extremely small subset of a sizeable cirrhotic cohort. When made, only a minority of these patients meet diagnostic criteria. Our findings highlight the need for improved education and more effective screening algorithms.

A Simple and Quick Screening Method for Intrapulmonary Vascular Dilation in Cirrhotic Patients Based on Machine Learning

Background and Aims

Screening for hepatopulmonary syndrome in cirrhotic patients is limited due to the need to perform contrast enhanced echocardiography (CEE) and arterial blood gas (ABG) analysis. We aimed to develop a simple and quick method to screen for the presence of intrapulmonary vascular dilation (IPVD) using noninvasive and easily available variables with machine learning (ML) algorithms.

Methods

Cirrhotic patients were enrolled from our hospital. All eligible patients underwent CEE, ABG analysis and physical examination. We developed a two-step model based on three ML algorithms, namely, adaptive boosting (termed AdaBoost), gradient boosting decision tree (termed GBDT) and eXtreme gradient boosting (termed Xgboost). Noninvasive variables were input in the first step (the NI model), and for the second step (the NIBG model), a combination of noninvasive variables and ABG results were used. Model performance was determined by the area under the curve of receiver operating characteristics (AUCROCs), precision, recall, F1-score and accuracy.

Results

A total of 193 cirrhotic patients were ultimately analyzed. The AUCROCs of the NI and NIBG models were 0.850 (0.738–0.962) and 0.867 (0.760–0.973), respectively, and both had an accuracy of 87.2%. For both negative and positive cases, the recall values of the NI and NIBG models were both 0.867 (0.760–0.973) and 0.875 (0.771–0.979), respectively, and the precisions were 0.813 (0.690–0.935) and 0.913 (0.825–1.000), respectively.

Conclusions

We developed a two-step model based on ML using noninvasive variables and ABG results to screen for the presence of IPVD in cirrhotic patients. This model may partly solve the problem of limited access to CEE and ABG by a large numbers of cirrhotic patients.

Hepatopulmonary Syndrome and Portopulmonary Hypertension: Pulmonary Vascular Complications of Liver Disease

Pulmonary vascular disease is a frequent complication of chronic liver disease and portal hypertension, affecting up to 30% of patients. There are two distinct pulmonary vascular complications of liver disease: hepatopulmonary syndrome (HPS) and portopulmonary hypertension (POPH). HPS affects 25% of patients with chronic liver disease and is characterized by intrapulmonary vasodilatation and abnormal arterial oxygenation. HPS negatively impacts quality of life and is associated with a 2-fold increased risk of death compared to controls with liver disease without HPS. Angiogenesis, endothelin-1 mediated endothelial dysfunction, monocyte influx, and alveolar type 2 cell dysfunction seem to play important roles in disease pathogenesis but there are currently no effective medical therapies. Fortunately, HPS resolves following liver transplant (LT) with improvements in hypoxemia. POPH is a subtype of pulmonary arterial hypertension (PAH) characterized by an elevated mean pulmonary arterial pressure and pulmonary vascular resistance in the setting of normal left-sided filling pressures. POPH affects 5% to 6% of patients with chronic liver disease. Although the pathogenesis has not been fully elucidated, endothelial dysfunction, inflammation, and estrogen signaling have been identified as key pathways involved in disease pathogenesis. POPH is typically treated with PAH targeted therapy and may also improve with liver transplantation in selected patients. This article highlights what is currently known regarding the diagnosis, management, pathobiology, and outcomes of HPS and POPH. Ongoing research is needed to improve understanding of the pathophysiology and outcomes of these distinct and often misunderstood pulmonary vascular complications of liver disease. © 2021 American Physiological Society. Compr Physiol 11:1-22, 2021.

Excellent outcomes with liver transplantation in hepatopulmonary syndrome across pre-transplant PaO2 spectrum

Background & Aims

Significantly worse survival has been reported in patients with hepatopulmonary syndrome (HPS) and partial pressure of arterial oxygen (PaO₂) <45 mmHg undergoing liver transplantation. Long-term pre- and post-transplant outcomes based on degree of hypoxaemia were re-examined.

Methods

A retrospective analysis of 1,152 HPS candidates listed with an approved HPS model for end-stage liver disease (MELD) exception was performed. A Fine and Gray competing risks model was utilised to evaluate pre-transplant outcomes for PaO₂ thresholds of <45, 45 to <60, and ≥60 mmHg. Post-transplant survival was analysed using the Kaplan-Meier method.

Results

Patients with a PaO₂ <45 mmHg were significantly more likely to undergo transplantation (hazard ratio [HR] 1.51; 95% CI 1.12-2.03), whereas patients with higher MELD scores had lower hazard of transplant (HR 0.80, 95% CI 0.67-0.95, p = 0.011) and higher hazard of pre-transplant death (HR 2.29, 95% CI 1.55-3.37, p <0.001). Post-transplantation, patients with a PaO₂ <45 mmHg had lower survival (p = 0.04) compared with patients with a PaO₂ ≥45 to <50 mmHg, with survival curves significantly different at 2.6 years (75% survival compared with 86%) and median survival of 11.5 and 14.1 years, respectively. Cardiac arrest was a more likely (p = 0.025) cause of death for these patients. Cardiac arrest incidence in patients who died with a PaO₂ >50 mmHg was 6.2%.

Conclusions

Patients with a PaO₂ <45 mmHg had a significantly higher rate of transplantation, and higher calculated MELD scores were associated with significantly higher pre-transplant mortality. Although post-transplant survival was lower in patients with a PaO₂ <45 mmHg, the median survival was 11.5 years, and survival curves only became significantly different at 2.6 years. This suggests that patients with HPS do benefit from transplantation up to 2-3 years post-transplant regardless of the severity of pre-transplant hypoxaemia.

Lay summary

A total of 1,152 patients with hepatopulmonary syndrome listed for liver transplant were analysed. Patients with a low PaO₂ <45 mmHg had a high likelihood of transplantation. If associated with advanced liver disease, the mortality risk was higher for patients with hepatopulmonary syndrome on the wait list. After liver transplantation, patients with a PaO₂ <45 mmHg had a lower survival, but this only became significant after 2.6 years, and the median survival was 11.5 years. This suggests that patients with hepatopulmonary syndrome do benefit from transplantation.

Point-of-Care Thoracic Ultrasonography in Patients With Cirrhosis and Liver Failure

Point-of-care ultrasonography (POCUS) helps determine liver-related pathologies like an abscess, portal vein or hepatic vein thromboses, presence of ascites, site for pleural or ascitic paracentesis, and guiding biopsies. POCUS is revolutionizing the management of critically ill patients presenting with pneumonia, acute respiratory distress syndrome, acute-on-chronic liver failure, and in the emergency. The objectives of thoracic ultrasonography (TUS) are to aid the clinician in differentiating between pneumonia, effusions, interstitial edema and collections, and in estimating the volume status of patients with liver disease using inferior vena cava dynamic indices. The use of POCUS in patients with cirrhosis has since evolved. It is now widely used to help diagnose volume status, left ventricular diastolic dysfunction, myocardial infarction, and right ventricular dilation due to pulmonary embolism and to determine the causes for weaning failures such as effusions, lung collapse, and pneumothorax. During the Coronavirus Disease 2019 (COVID-19) pandemic, moving patients for computed tomography can be difficult. Therefore, TUS is now essential in liver transplantation and intensive care practice to assess ventilatory pressures, cardiac function, and fluid management. This review indicates the current and optimized use of TUS, offers a practical guide on TUS in the liver intensive care unit (ICU), and presents a diagnostic pathway for determining lung and pleural pathology, resolution of respiratory failure, and aid weaning from mechanical ventilation.

Point-of-Care Echocardiography and Hemodynamic Monitoring in Cirrhosis and Acute-on-Chronic Liver Failure in the COVID-19 Era

Point-of-Care (POC) transthoracic echocardiography (TTE) is transforming the management of patients with cirrhosis presenting with septic shock, acute kidney injury, hepatorenal syndrome and acute-on-chronic liver failure (ACLF) by correctly assessing the hemodynamic and volume status at the bedside using combined echocardiography and POC ultrasound (POCUS). When POC TTE is performed by the hepatologist or intensivist in the intensive care unit (ICU), and interpreted remotely by a cardiologist, it can rule out cardiovascular conditions that may be contributing to undifferentiated shock, such as diastolic dysfunction, myocardial infarction, myocarditis, regional wall motion abnormalities and pulmonary embolism. The COVID-19 pandemic has led to a delay in seeking medical treatment, reduced invasive interventions and deferment in referrals leading to "collateral damage" in critically ill patients with liver disease. Thus, the use of telemedicine in the ICU (Tele-ICU) has integrated cardiology, intensive care, and hepatology practices across the spectrum of ICU, operating room, and transplant healthcare. Telecardiology tools have improved bedside diagnosis when introduced as part of COVID-19 care by remote supervision and interpretation of POCUS and echocardiographic data. In this review, we present the contemporary approach of using POC echocardiography and offer a practical guide for primary care hepatologists and gastroenterologists for cardiac assessment in critically ill patients with cirrhosis and ACLF. Evidenced based use of Tele-ICU can prevent delay in cardiac diagnosis, optimize safe use of expert resources and ensure timely care in the setting of critically ill cirrhosis, ACLF and liver transplantation in the COVID-19 era.

Prevalence and determinants of hepatopulmonary syndrome in decompensated chronic liver disease

BACKGROUND

One of the severe complications of liver disease is hepatopulmonary syndrome (HPS). There is paucity in literature regarding the various factors associated with the development of HPS. This study was conducted to analyze the prevalence and determinants of HPS among patients with decompensated chronic liver disease (CLD).

METHODS

This study was a cross-sectional-observational study conducted in a tertiary care center. Decompensated CLD patients admitted for pre-liver transplant workup were included in the study. Demographic data, clinical findings, and biochemical and hematologic parameters were collected. Pulse oximetry, arterial blood gas analysis, bubble contrast echocardiogram, diffusion capacity of the lungs for carbon monoxide (DLCO), and spirometry were done to get the needed parameters. All data were entered into a Microsoft Excel sheet and analyzed using the statistical software SPSS for Windows, version 22.0.

RESULTS

Among 64 subjects, 58 were men (90.6%). Mean age was 54.5 years. HPS was present in 26 (40.6%) patients. Platypnea and orthodeoxia were present more often in HPS patients. DLCO was significantly impaired among patients with HPS. Portopulmonary hypertension was seen in 8 (12.5%) subjects with no difference between HPS and non-HPS patients. Subjects with HPS had more severe liver disease. A model for end-stage liver disease (MELD)-Na score > 19 was associated with HPS (sensitivity 73.08%, specificity 65.79%, PPV 59.4%, and NPV 78.1%). Multivariate analysis (binary logistic regression) revealed that a higher MELD-Na score, hepatic encephalopathy, and impaired DLCO were independently associated with HPS.

CONCLUSIONS

HPS is associated with more severe liver disease (as per Child-Turcotte-Pugh [CTP] stage and MELD-Na score). There was no relation between HPS and causes of CLD. Higher MELD-Na score, hepatic encephalopathy, impaired DLCO, clubbing, and spider naevi were independently associated with HPS.

Outcomes of 50 Cases of Pediatric Liver Transplantation for Intrapulmonary Shunt While Considering the Deteriorated Prognosis of Severe Intrapulmonary Shunt Patients

BACKGROUND

Intrapulmonary shunt (IPS) is recognized in 10% of chronic liver disease patients. Liver transplantation (LT) is associated with a high risk of morbidity and mortality in patients with IPS.

PATIENTS AND METHODS

Of 519 pediatric LT cases between November 2005 and October 2018, 50 patients with IPS were enrolled in this study. The patients were divided into 3 groups, according to the shunt ratio, calculated by scintigraphy: mild (15%-20%, n = 26), moderate (20%-40%, n = 19), and severe (> 40%, n = 5). We compared the patients' characteristics before LT and the outcomes of LT between these groups.

RESULTS

The major original disease resulting in LT in the mild and moderate groups was biliary atresia (73.1% and 52.6%, respectively), while that in the severe group was congenital portosystemic shunt (60%). The median ages at LT were 7.5, 6.1, and 8.3 years in the mild, moderate, and severe groups, respectively. All of the mild and moderate IPS patients lived; however, 3 patients with severe IPS (60.0%) died within 3 months. The shunt ratios of the mild and moderate IPS patients normalized within 2 years after LT, while the 2 surviving severe IPS patients showed a slight improvement. The autopsy findings of the lung in 1 deceased severe IPS patient showed medial hypertrophy and proliferation of intimal cells of the pulmonary arteries, suggesting a diagnosis of portopulmonary hypertension.

CONCLUSIONS

LT can be safely performed for mild and moderate IPS patients; however, LT for severe IPS patients should be carefully indicated because concomitant portopulmonary hypertension may be masked by IPS.

Value of Contrast Transesophageal Echocardiography in the Detection of Intrapulmonary Vascular Dilatations in Hepatosplenic Schistosomiasis

Background

Hepatopulmonary syndrome (HPS), found in cirrhotic patients, has been little studied in hepatosplenic schistosomiasis (HSS) and includes the occurrence of intrapulmonary vascular dilatations (IPVD). Contrast transesophageal echocardiography (cTEE) with microbubbles is more sensitive than contrast transthoracic echocardiography (cTTE) with microbubbles in the detection of IPVD in cirrhosis.

Objective

To assess the performance of the cTEE, compared with that of cTTE, in detecting IPVD for the diagnosis of HPS in patients with HSS.

Methods

cTEE and cTTE for investigation of IPVD and laboratory tests were performed in 22 patients with HSS. Agitated saline solution was injected in peripheral vein during the cTEE and cTTE procedures. Late appearance of the microbubbles in the left chambers indicated the presence of IPVD. Results of the two methods were compared by the Student’s t-test and the chi-square test (p < 0.05).

Results

cTEE was performed in all patients without complications. Three patients were excluded due to the presence of patent foramen ovale (PFO). The presence of IPVD was confirmed in 13 (68%) of 19 patients according to the cTEE and in only six (32%, p < 0.01) according to the cTTE. No significant differences in clinical or laboratory data were found between the groups with and without IPVD, including the alveolar-arterial gradient. The diagnosis of HPS (presence of IPVD with changes in the arterial blood gas analysis) was made in five patients by the cTEE and in only one by the cTTE (p = 0.09).

Conclusion

In HSS patients, cTEE was safe and superior to cTTE in detecting IPVD and allowed the exclusion of PFO.

A subclinical high tricuspid regurgitation pressure gradient independent of the mean pulmonary artery pressure is a risk factor for the survival after living donor liver transplantation

BACKGROUND

Portopulmonary hypertension (POPH) is characterized by pulmonary vasoconstriction, while hepatopulmonary syndrome (HPS) is characterized by vasodilation. Definite POPH is a risk factor for the survival after orthotopic liver transplantation (OLT), as the congestive pressure affects the grafted liver, while subclinical pulmonary hypertension (PH) has been acknowledged as a non-risk factor for deceased donor OLT. Given that PH measurement requires cardiac catheterization, the tricuspid regurgitation pressure gradient (TRPG) measured by echocardiography is used to screen for PH and congestive pressure to the liver. We investigated the impact of a subclinical high TRPG on the survival of small grafted living donor liver transplantation (LDLT).

METHODS

We retrospectively analyzed 84 LDLT candidates. Patients exhibiting a TRPG ≥25 mmHg on echocardiography were categorized as potentially having liver congestion (subclinical high TRPG; n = 34). The mean pulmonary artery pressure (mPAP) measured after general anesthesia with FIO₂0.6 (mPAP-FIO₂0.6) was also assessed. Patients exhibiting pO₂ < 80 mmHg and an alveolar-arterial oxygen gradient (AaDO₂) ≥ 15 mmHg were categorized as potentially having HPS (subclinical HPS; n = 29). The clinical course after LDLT was investigated according to subclinical high TRPG.

RESULTS

A subclinical high TRPG (p = 0.012) and older donor age (p = 0.008) were correlated with a poor 40-month survival. Although a higher mPAP-FIO₂0.6 was expected to correlate with a worse survival, a high mPAP-FIO₂0.6 with a low TRPG was associated with high frequency complicating subclinical HPS and a good survival, suggesting a reduction in the PH pressure via pulmonary shunt.

CONCLUSION

In cirrhosis patients, mPAP-FIO₂0.6 may not accurately reflect the congestive pressure to the liver, as the pressure might escape via pulmonary shunt. A subclinical high TRPG is an important marker for predicting a worse survival after LDLT, possibly reflecting congestive pressure to the grafted small liver.

Review article: Update on current and emergent data on hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is a frequent pulmonary complication of end-stage liver disease, characterized by impaired arterial oxygenation induced by intrapulmonary vascular dilatation. Its prevalence ranges from 4% to 47% in patients with cirrhosis due to the different diagnostic criteria applied among different studies. Nitric oxide overproduction and angiogenesis seem to be the hallmarks of a complicated pathogenetic mechanism, leading to intrapulmonary shunting and ventilation-perfusion mismatch. A classification of HPS according to the severity of hypoxemia has been suggested. Contrast-enhanced echocardiography represents the gold standard method for the detection of intrapulmonary vascular dilatations which is required, in combination with an elevated alveolar arterial gradient to set the diagnosis. The only effective treatment which can modify the syndrome’s natural history is liver transplantation. Although it is usually asymptomatic, HPS imparts a high risk of pretransplantation mortality, independently of the severity of liver disease, while there is variable data concerning survival rates after liver transplantation. The potential of myocardial involvement in the setting of HPS has also gained increasing interest in recent research. The aim of this review is to critically approach the existing literature of HPS and emphasize unclear points that remain to be unraveled by future research.

Hepatopulmonary Disorders: Gas Exchange and Vascular Manifestations in Chronic Liver Disease

This review concentrates on the determinants of gas exchange abnormalities in liver-induced pulmonary vascular disorders, more specifically in the hepatopulmonary syndrome. Increased alveolar-arterial O₂ difference, with or without different levels of arterial hypoxemia, and reduced diffusing capacity represent the most characteristic gas exchange disturbances in the absence of cardiac and pulmonary comorbidities. Pulmonary gas exchange abnormalities in the hepatopulmonary syndrome are unique encompassing all three pulmonary factors determining arterial PO₂ , that is, ventilation-perfusion imbalance, increased intrapulmonary shunt and oxygen diffusion limitation that, combined, interplay with two relevant nonpulmonary determinants, that is, increased total ventilation and high cardiac output. Behind the complexity of this lung-liver association there is an abnormal pulmonary vascular tone that combines inhibition of hypoxic pulmonary vasoconstriction with a reduced (or blunted) hypoxic vascular response. The pathology and pathobiology include the presence of intrapulmonary vascular dilatations with or without pulmonary vascular remodeling, i.e. angiogenesis. Liver transplantation, the only effective therapeutic approach to successfully improve and resolve the vast majority of complications induced by the hepatopulmonary syndrome, along with a large list of frustrating pharmacologic interventions, are also reviewed. Another liver-induced pulmonary vascular disorder with less gas exchange involvement, such as portopulmonary hypertension, is also considered. © 2018 American Physiological Society. Compr Physiol 8:711-729, 2018.

Clinical Impact of Intrapulmonary Vascular Dilatation in Candidates for Liver Transplant

BACKGROUND

Intrapulmonary vascular dilatations (IPVD) frequently are detected in patients with liver disease by the delayed appearance of microbubbles at contrast-enhanced echocardiography. IPVD with an elevated alveolar-arterial (A-a) gradient define hepatopulmonary syndrome (HPS); however, the importance of IPVD in the absence of abnormal gas exchange is unknown. We aimed to determine the clinical impact of IPVD in patients with liver disease.

METHODS

We performed a cross-sectional study within the Pulmonary Vascular Complications of Liver Disease 2 Study, a multicenter, prospective cohort study of patients being evaluated for liver transplant. We excluded patients with obstructive or restrictive lung disease, HPS, or intracardiac shunting. We compared patients with and those without IPVD.

RESULTS

Forty-six patients with IPVD and 81 patients without IPVD were included. Patients with IPVD were more likely to have autoimmune hepatitis and less likely to have cryptogenic cirrhosis and hepatocellular carcinoma. Patients with IPVD had higher Child-Pugh scores (6 [interquartile range (IQR), 5-7] vs 5 [IQR, 4-7]; P = .04), possibly higher Model for End-Stage Liver Disease scores (14.5 [IQR, 11.6-15.8] vs 12.2 [IQR, 9.4-15.5]; P = .06), higher PaO₂ levels (97.9 [IQR, 92.0-103.0] vs 89.0 [IQR, 82.0-96.9] mm Hg; P < .001), and lower A-a gradients (9.9 [IQR, 6.2-13.5] vs 14.9 [IQR, 9.0-21.8] mm Hg; P < .001). Symptoms and quality of life were similar between the groups.

CONCLUSIONS

Autoimmune hepatitis and increased liver disease severity were associated with the presence of IPVD, which was characterized by higher PaO₂ levels. Future studies to better characterize IPVD pathogenesis and the relationship of IPVD to HPS are warranted.

International Liver Transplant Society Practice Guidelines: Diagnosis and Management of Hepatopulmonary Syndrome and Portopulmonary Hypertension

Two distinct pulmonary vascular disorders, hepatopulmonary syndrome (HPS) and portopulmonary hypertension (POPH) may occur as a consequence of hepatic parenchymal or vascular abnormalities. HPS and POPH have major clinical implications for liver transplantation. A European Respiratory Society Task Force on Pulmonary-Hepatic Disorders convened in 2002 to standardize the diagnosis and guide management of these disorders. These International Liver Transplant Society diagnostic and management guidelines are based on that task force consensus and should continue to evolve as clinical experience dictates. Based on a review of over 1000 published HPS and POPH articles identified via a MEDLINE search (1985-2015), clinical guidelines were based on, selected single care reports, small series, registries, databases, and expert opinion. The paucity of randomized, controlled trials in either of these disorders was noted. Guidelines are presented in 5 parts; I. Definitions/Diagnostic criteria; II. Hepatopulmonary syndrome; III. Portopulmonary hypertension; IV. Implications for liver transplantation; and V. Suggestions for future clinical research.

Current Approach to the Diagnosis and Management of Portopulmonary Hypertension

Portopulmonary hypertension (POPH) is a form of pulmonary arterial hypertension occurring in the setting of portal hypertension with or without hepatic cirrhosis. The presence of both portal and pulmonary vascular disease contributes to complicated hemodynamics and therapeutic challenges, though the severities do not appear to correlate directly. Diagnosis of POPH, and distinction from the commonly observed hyperdynamic state of end-stage liver disease, is typically accomplished with an initial screening transthoracic echocardiogram, followed by right heart catheterization for confirmation of hemodynamic parameters. Though few studies have directly evaluated use in POPH, pulmonary artery-directed therapy is the cornerstone of management, along with consideration of liver transplantation. Perioperative and long-term outcomes are variable, but uniformly worse in the setting of uncontrolled pulmonary pressures. Risk stratification and optimal patient selection for these interventions are areas of ongoing investigation.

Prolonged Unexplained Hypoxemia as Initial Presentation of Cirrhosis: A Case Report

Patient: Male, 43

Final Diagnosis: Hepatopulmonary syndrome

Symptoms: Dyspnea

Medication: —

Clinical Procedure: —

Specialty: Gastroenterology and Hepatology

Inflammatory bowel diseases, chronic liver diseases and the lung

This review is devoted to the distinct associations of inflammatory bowel diseases (IBD) and chronic liver disorders with chronic airway diseases, namely chronic obstructive pulmonary disease and bronchial asthma, and other chronic respiratory disorders in the adult population. While there is strong evidence for the association of chronic airway diseases with IBD, the data are much weaker for the interplay between lung and liver multimorbidities. The association of IBD, encompassing Crohn's disease and ulcerative colitis, with pulmonary disorders is underlined by their heterogeneous respiratory manifestations and impact on chronic airway diseases. The potential relationship between the two most prevalent liver-induced pulmonary vascular entities, i.e. portopulmonary hypertension and hepatopulmonary syndrome, and also between liver disease and other chronic respiratory diseases is also approached. Abnormal lung function tests in liver diseases are described and the role of increased serum bilirubin levels on chronic respiratory problems are considered.