Pulse Oximetry Is Insensitive for Detection of Hepatopulmonary Syndrome in Patients Evaluated for Liver Transplantation

Angiographic tool to detect pulmonary arteriovenous malformations in single ventricle physiology

OBJECTIVE

Individuals with single ventricle physiology who are palliated with superior cavopulmonary anastomosis (Glenn surgery) may develop pulmonary arteriovenous malformations. The traditional tools for pulmonary arteriovenous malformation diagnosis are often of limited diagnostic utility in this patient population. We sought to measure the pulmonary capillary transit time to determine its value as a tool to identify pulmonary arteriovenous malformations in patients with single ventricle physiology.

METHODS

We defined the angiographic pulmonary capillary transit time as the number of cardiac cycles required for transit of contrast from the distal pulmonary arteries to the pulmonary veins. Patients were retrospectively recruited from a single quaternary North American paediatric centre, and angiographic and clinical data were reviewed. Pulmonary capillary transit time was calculated in 20 control patients and compared to 20 single ventricle patients at the pre-Glenn, Glenn, and Fontan surgical stages (which were compared with a linear-mixed model). Correlation (Pearson) between pulmonary capillary transit time and haemodynamic and injection parameters was assessed using angiograms from 84 Glenn patients. Five independent observers calculated pulmonary capillary transit time to measure reproducibility (intraclass correlation coefficient).

RESULTS

Mean pulmonary capillary transit time was 3.3 cardiac cycles in the control population, and 3.5, 2.4, and 3.5 in the pre-Glenn, Glenn, and Fontan stages, respectively. Pulmonary capillary transit time in the Glenn population did not correlate with injection conditions. Intraclass correlation coefficient was 0.87.

CONCLUSIONS

Pulmonary angiography can be used to calculate the pulmonary capillary transit time, which is reproducible between observers. Pulmonary capillary transit time accelerates in the Glenn stage, correlating with absence of direct hepatopulmonary venous flow.

Favorable Outcomes of Liver Transplantation for Hepatopulmonary Syndrome

BACKGROUND

Hepatopulmonary syndrome (HPS) is a pulmonary vascular complication of chronic liver disease, which develops insidiously as a result of chronic liver disease. The prognosis for untreated patients with HPS is extremely poor, and liver transplantation (LT) serves as the only effective means for treating this condition. Here, we performed a retrospective analysis to evaluate the efficacy of LT on the survival and long-term prognosis of patients with HPS.

METHODS

Clinical data, including survival and postoperative efficacy, from patients with HPS from records as obtained over the period from January 1 to December 31, 2022. All records were from a waiting list for LT at the Beijing Friendship Hospital Affiliated with Capital Medical University.

RESULTS

Among the 274 patients on the LT waiting list, 37 were diagnosed with HPS (13.50%) and were enrolled. Survival rates of patients with HPS receiving an LT were greater, whereas a statistically significant difference was obtained between patients with LT vs non-LT with moderate to severe HPS (P = .003). The overall time until death without LT was 4-72 days after their initial HPS diagnosis. Patients with HPS receiving an LT showed a significant improvement in the state of oxygenation after surgery (P = .001).

CONCLUSION

Comprehensive preoperative screening of patients on the waiting list for LT is critical to identify those patients with HPS who would maximally benefit from LT. Survival rates of patients with moderate to severe HPS are significantly increased after LT, a procedure that should be performed as soon as possible in these patients with HPS.

[Hepatopulmonary syndrome]

The hepatopulmonary syndrome (HPS) is one of the lung diseases associated with cirrhosis and portal hypertension. It should be discussed for any dyspnea in cirrhotic patients. HPS is a pulmonary vascular disease characterized by intrapulmonary vascular dilatations (IPVD). The pathogenesis is complex and seems to rely on communications between the portal and pulmonary circulations. The diagnosis is based on a triad of liver disease and portal hypertension, evidence of IPVDs, and impaired gas exchange (alveolar-arterial oxygen difference [A-aO2]≥15mmHg). HPS impairs prognosis (23% survival at 5years) and patients' quality of life. Liver transplantation (LT) allows regression of IPDVD in almost 100% of cases, normalization of gas exchange and improves survival with a 5-year post-LT survival between 76 and 87%. It is the only curative treatment, indicated in patients with severe HPS, defined by an arterial partial pressure of oxygen (PaO2) below 60mmHg. When LT is not indicated or feasible, long-term oxygen therapy may be proposed as a palliative treatment. A better understanding of the pathophysiological mechanisms is needed to improve the therapeutic possibilities in a near future.

Angiographic Tool to Detect Pulmonary Arteriovenous Malformations in Single Ventricle Physiology

Background

Individuals with single ventricle physiology who are palliated with superior cavopulmonary anastomosis (Glenn surgery) may develop pulmonary arteriovenous malformations (PAVMs). The traditional tools for PAVM diagnosis are often of limited diagnostic utility in this patient population. We sought to measure the pulmonary capillary transit time (PCTT) to determine its value as a tool to identify PAVMs in patients with single ventricle physiology.

Methods

We defined the angiographic PCTT as the number of cardiac cycles required for transit of contrast from the distal pulmonary arteries to the pulmonary veins. Patients were retrospectively recruited from a single quaternary North American pediatric center, and angiographic and clinical data was reviewed. PCTT was calculated in 20 control patients and compared to 20 single ventricle patients at the pre-Glenn, Glenn, and Fontan surgical stages (which were compared with a linear-mixed model). Correlation (Pearson) between PCTT and hemodynamic and injection parameters was assessed using 84 Glenn angiograms. Five independent observers calculated PCTT to measure reproducibility (intra-class correlation coefficient).

Results

Mean PCTT was 3.3 cardiac cycles in the control population, and 3.5, 2.4, and 3.5 in the pre-Glenn, Glenn, and Fontan stages, respectively. PCTT in the Glenn population did not correlate with injection conditions. Intraclass correlation coefficient was 0.87.

Conclusions

Pulmonary angiography can be used to calculate the pulmonary capillary transit time, which is reproducible between observers. PCTT accelerates in the Glenn stage, correlating with absence of direct hepatopulmonary venous flow.

LTSI Consensus Guidelines: Preoperative Pulmonary Evaluation in Adult Liver Transplant Recipients

The relationship between chronic liver disease and respiratory symptoms and hypoxia is well recognized. Over the last century, three pulmonary complications specific to chronic liver disease (CLD) have been characterized: hepatopulmonary syndrome, portopulmonary hypertension, and hepatic hydrothorax. Apart from that coexisting pulmonary disease like chronic obstructive lung disease and interstitial lung disease also complicate the outcomes after liver transplantation (LT). Assessment for evaluation of underlying pulmonary disorders is essential to improve outcomes in patients with CLD, posted for LT. This consensus guideline of the Liver Transplant Society of India (LTSI) provides a comprehensive review of pulmonary issues in CLD, related and unrelated to underlying liver disease and gives recommendations for pulmonary screening in specific clinical scenarios in adults with chronic liver disease planned for LT. This document also aims to standardize the strategies for preoperative evaluation of these pulmonary issues in this subset of patients. Proposed recommendations were based on selected single case reports, small series, registries, databases, and expert opinion. The paucity of randomized, controlled trials in either of these disorders was noted. Additionally, this review will highlight the lacunae in our current evaluation strategy, challenges faced, and will provide direction to potentially useful futuristic preoperative evaluation strategies.

Impact of hepatopulmonary syndrome in liver transplantation candidates and the role of angiogenesis

BACKGROUND

Hepatopulmonary syndrome affects 10-30% of patients with cirrhosis and portal hypertension. We evaluated the serum angiogenic profile of hepatopulmonary syndrome and assessed the clinical impact of hepatopulmonary syndrome in patients evaluated for liver transplantation.

METHODS

The Pulmonary Vascular Complications of Liver Disease 2 study was a multicentre, prospective cohort study of adults undergoing their first liver transplantation evaluation. Hepatopulmonary syndrome was defined as an alveolar-arterial oxygen gradient ≥15 mmHg (≥20 mmHg if age >64 years), positive contrast-enhanced transthoracic echocardiography and absence of lung disease.

RESULTS

We included 85 patients with hepatopulmonary syndrome and 146 patients without hepatopulmonary syndrome. Patients with hepatopulmonary syndrome had more complications of portal hypertension and slightly higher Model for End-Stage Liver Disease-Na score compared to those without hepatopulmonary syndrome (median (interquartile range) 15 (12-19) versus 14 (10-17), p=0.006). Hepatopulmonary syndrome patients had significantly lower 6-min walk distance and worse functional class. Hepatopulmonary syndrome patients had higher circulating angiopoietin 2, Tie2, tenascin C, tyrosine protein kinase Kit (c-Kit), vascular cell adhesion molecule 1 and von Willebrand factor levels, and lower E-selectin levels. Patients with hepatopulmonary syndrome had an increased risk of death (hazard ratio 1.80, 95% CI 1.03-3.16, p=0.04), which persisted despite adjustment for covariates (hazard ratio 1.79, 95% CI 1.02-3.15, p=0.04). This association did not vary based on levels of oxygenation, reflecting the severity of hepatopulmonary syndrome.

CONCLUSION

Hepatopulmonary syndrome was associated with a profile of abnormal systemic angiogenesis, worse exercise and functional capacity, and an overall increased risk of death.

Hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is a pulmonary vascular complication of liver disease, which adversely affects prognosis. The disease is characterised by intrapulmonary vascular dilatations and shunts, resulting in impaired gas exchange. A complex interaction between the liver, the gut and the lungs, predominately impacting pulmonary endothelial cells, immune cells and respiratory epithelial cells, is responsible for the development of typical pulmonary alterations seen in HPS. Liver transplantation is the only therapeutic option and generally reverses HPS. Since the implementation of the model for end-stage liver disease (MELD) standard exception policy, outcomes in patients with HPS have been significantly better than they were in the pre-MELD era. This review summarises current knowledge and highlights what’s new regarding the diagnosis and management of HPS, and our understanding of pathogenesis based on experimental models and translational studies.

Unmasking Hypoxia in Cirrhosis Patients: Six-Minute Walk Test as a Screening Tool for Hepatopulmonary Syndrome

Background

Hepatopulmonary syndrome (HPS) is one of the complications of advanced cirrhosis which has a serious impact on prognosis of patient. Finding arterial deoxygenation early and initiating higher-level treatment is one of the most critical strategies in the therapy of HPS. In this study, we aimed to assess the utility of six-minute walk test (6MWT) in the diagnosis of HPS.

Materials and Methods

We have enrolled 100 consecutive cirrhosis patients referred to the Liver Clinic of a tertiary care centre of India for >1 year. The Child-Pugh score and the MELD score were used to determine the severity of cirrhosis. All the patients underwent transthoracic contrast echocardiography, arterial blood gas measurements on room air, 6MWT, and chest imaging.

Results

A total of 100 patients were included in the study after fulfilling the inclusion criteria. HPS was present in 21 out of 100 patients (21%). Median (twenty fifth to seventy fifth percentile) MELD score in patients with HPS was 29 (26-33), which was significantly higher as compared to patients without HPS 22 (14.5-26); P <.0001. The 6MWT was positive in 20 (95.23%) HPS patients, while only 1 patient (4.77%) of HPS had negative 6MWT. If 6MWT is positive, then there was 76.92% probability of HPS and if 6MWT is negative, then 98.65% chances of no HPS.

Conclusion

The 6MWT is a simple and effective screening test for HPS, it helps in identifying the patients early who have a potential to deteriorate. This simple intervention would help in prioritizing patients for liver transplantation as liver transplant is the only effective treatment for HPS.

Pulmonary complications of portal hypertension: The overlooked decompensation

The systemic nature of cirrhosis and portal hypertension has long been recognized, and the amount of data characterizing the interplay between each system is becoming ever so complex. Lung involvement was among the first described associated entities in cirrhosis, with reports dating back to the late nineteenth century. However, it appears that throughout the years, interest in the pulmonary complications of portal hypertension has generally faded, especially in contrast to other decompensating events, as expertise in this field has primarily been concentrated in highly experienced tertiary care facilities and liver transplantation centers. Despite affecting up to 10%-15% of patients with advanced liver disease and having a proven prognostic impact, hepato-pulmonary syndrome, porto-pulmonary hypertension, and hepatic hydrothorax are frequently misdiagnosed, mistreated, or misinterpreted. This lack of precision might adversely impact patient care, referral to expert centers, and, ultimately, liver disease-related mortality and successful transplantation odds. The present minireview aims to increase awareness of the pulmonary complications of chronic liver disease by providing a brief overview of each of the three entities. The paper focuses on the essential theoretical aspects, addressing the most critical knowledge gaps on the one hand and, on the other hand, critically discussing one key issue for each complication.

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.

Recent advances in the approach to hepatopulmonary syndrome and portopulmonary hypertension

Liver disease, cirrhosis and portal hypertension can be complicated by pulmonary vascular disease, which may affect prognosis and influence liver transplantation (LT) candidacy. Pulmonary vascular complications comprise hepatopulmonary syndrome (HPS) and portopulmonary hypertension (POPH). Although these two conditions develop on a same background and share a common trigger, pulmonary responses are distinct and occur at different anatomical sites of the pulmonary circulation. HPS affects 10-30% of patients referred for LT, and is characterized by gas exchange abnormalities due to pulmonary vasodilation and right-to-left shunting. POPH occurs in 5%, and is defined by pulmonary arterial hypertension due to increased pulmonary vascular resistance, which leads to hemodynamic failure. Even though HPS and POPH may have a substantial negative impact on survival, both entities are clinically underrecognized and frequently misdiagnosed. Without intervention, the 5-year survival rate is 23% in HPS and 14% in POPH. Their presence should be actively sought by organized screening in patients presenting with dyspnea and in all patients on the waitlist for LT, also because clinical symptoms are commonly non-specific or even absent. LT may lead to resolution, however, advanced stages of either HPS or POPH may jeopardize safe and successful LT. This implicates the need of proper identification of HPS and POPH cases, as well as the need to be able to successfully 'bridge' patients to LT by medical intervention. A review article on this topic has been published in this journal in 2007 (1). This updated review focuses on recent advances in the diagnosis and management of these 2 liver-induced pulmonary vascular disorders and incorporates results from our recent work.

Analogies and differences between cirrhotic cardiomyopathy and hepatopulmonary syndrome

Cirrhotic cardiomyopathy and hepatopulmonary syndrome are two quite frequent clinical entities that may complicate the course of liver cirrhosis. The common pathophysiological origin and the same clinical presentation make them difficult to compare. Cirrhotic cardiomyopathy and hepatopulmonary syndrome may start with dyspnea and breathlessness but the former is characterized by a chronic cardiac dysfunction and the latter by a defect of oxygenation due to pulmonary shunts formation. The focus is to differentiate them as soon as possible since the treatment is different until the patient undergoes liver transplant that is the real unique cure for them.

Hepatopulmonary Syndrome and Portopulmonary Hypertension: Current Status and Implications for Liver Transplantation

PURPOSE OF REVIEW

Hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PoPH) are both pulmonary vascular complications of advanced liver disease; however, these syndromes have distinct pathophysiology, clinical implications, and management.

RECENT FINDINGS

While both conditions are associated with portal hypertension, HPS results from diffuse pulmonary capillary vasodilation and PoPH results from vasoconstriction and vascular remodeling of pulmonary arteries. In HPS, no medical therapies clearly improve outcomes; however, patients have excellent post-LT outcomes with near uniform reversal of hypoxemia. In PoPH, several medical therapies used in idiopathic pulmonary hypertension have been shown improve pulmonary hemodynamics, symptoms, and potentially LT outcomes; however, further study is needed to determine best treatment regimens, long-term outcomes on medical therapy, and role of LT.

SUMMARY

While HPS results in severe hypoxemia that is usually reversible by LT, PoPH patients develop progressive pulmonary hypertension that may improve with medical therapy.

Prevalence and Impact of Restrictive Lung Disease in Liver Transplant Candidates

We investigated the prevalence of spirometric restriction in liver transplantation (LT) candidates and the clinical impacts of restriction. We performed a cross-sectional study within the Pulmonary Vascular Complications of Liver Disease 2 (PVCLD2) study, a multicenter prospective cohort study of patients being evaluated for LT. Patients with obstructive lung disease or missing spirometry or chest imaging were excluded. Patients with and without restriction, defined as a forced vital capacity (FVC) <70% predicted, were compared. Restriction prevalence was 18.4% (63/343). Higher Model for End-Stage Liver Disease-sodium score (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.02-1.11; P = 0.007), the presence of pleural effusions (OR, 3.59; 95% CI, 1.96-6.58; P < 0.001), and a history of ascites (OR, 2.59; 95% CI, 1.26-5.33; P = 0.01) were associated with the presence of restriction, though one-third with restriction had neither pleural effusions nor ascites. In multivariate analysis, restriction was significantly and independently associated with lower 6-minute walk distances (least squares mean, 342.0 [95% CI, 316.6-367.4] m versus 395.7 [95% CI, 381.2-410.2] m; P < 0.001), dyspnea (OR, 2.69; 95% CI, 1.46-4.95; P = 0.002), and lower physical component summary Short Form 36 scores indicating worse quality of life (least squares mean, 34.1 [95% CI, 31.5-36.7] versus 38.2 [95% CI, 36.6-39.7]; P = 0.004). Lower FVC percent predicted was associated with an increased risk of death (hazard ratio, 1.16; 95% CI, 1.04-1.27 per 10-point decrease in FVC percent predicted; P = 0.01). Restriction and abnormal lung function are common in LT candidates; can be present in the absence of an obvious cause, such as pleural effusions or ascites; and is associated with worse exercise capacity, quality of life, and survival.

Pulmonary manifestations of chronic liver disease: a comprehensive review

Hepatopulmonary syndrome (HPS) and porto-pulmonary hypertension (PoPH) represent relatively common pulmonary vascular complications of advanced liver disease. Despite distinct differences in their pathogenetic background, both clinical states are characterized by impaired arterial oxygenation and limited functional status, and are associated with increased pre-transplantation mortality. Accumulation of ascitic fluid in the pleural cavity, known as hepatic hydrothorax (HH), is another frequent manifestation of decompensated cirrhosis, which may cause severe respiratory dysfunction, depending on the volume of the effusion, the rapidity of its development and its resistance to therapeutic measures. Orthotopic liver transplantation constitutes the only effective treatment able to resolve the pulmonary complications of liver disease. A prioritization policy for liver transplantation has evolved over the past years regarding advanced stages of HPS, yielding favorable outcomes regarding post-transplantation survival and HPS resolution. In contrast, severe PoPH is associated with poor post-transplantation survival. Hence, liver transplantation is recommended only for patients with PoPH and an acceptable reduction in pulmonary pressure values, after receiving PoPH-targeted vasodilating therapy. This review focuses on basic pathogenetic and diagnostic principles and discusses the current therapeutic approaches regarding HPS, PoPH, and HH.

Preoperative cardiac assessment in liver transplant candidates

New and extended indications, older age, higher cardiovascular risk, and the long-standing cirrhosis-associated complications mandate specific skills for an appropriate preoperative assessment of the liver transplant (LT) candidate. The incidence of cardiac diseases (dysrhythmias, cardiomyopathies, coronary artery disease, valvular heart disease) are increasing among LT recipients: however, no consensus exists among clinical practice guidelines for cardiovascular screening and risk stratification. In spite of different "transplant center-centered protocols", basic "pillars" are common (electrocardiography, baseline echocardiography, functional assessment). Owing to intrinsic limitations, yields and relevance of noninvasive stress tests, under constant scrutiny even if used, are discussed, focusing the definition of the "high risk" candidate and exploring noninvasive imaging and new forms of stress imaging. The aim is to find an appropriate and rational stepwise algorithm. The final commitment is to select the right candidate for a finite resource, the graft, able to save (and change) lives.

Pulmonary Complications of Portal Hypertension

The most common pulmonary complications of chronic liver disease are hepatic hydrothorax, hepatopulmonary syndrome, and portopulmonary hypertension. Hepatic hydrothorax is a transudative pleural effusion in a patient with cirrhosis and no evidence of underlying cardiopulmonary disease. Hepatic hydrothorax develops owing to the movement of ascitic fluid into the pleural space. Hepatopulmonary syndrome and portopulmonary hypertension are pathologically linked by the presence of portal hypertension; however, their pathophysiologic mechanisms are significantly different. Hepatopulmonary syndrome is characterized by low pulmonary vascular resistance secondary to intrapulmonary vascular dilatations and hypoxemia; portopulmonary hypertension features elevated pulmonary vascular resistance and constriction/obstruction within the pulmonary vasculature.

Sorafenib in Hepatopulmonary Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial

The tyrosine kinase inhibitor sorafenib improves hepatopulmonary syndrome (HPS) in an experimental model. However, the efficacy and adverse effect profile in patients with HPS are unknown. We aimed to determine the effect of sorafenib on the alveolar-arterial oxygen gradient (AaPO₂ ) at 3 months in patients with HPS. We performed a randomized, double-blind, placebo-controlled parallel trial of sorafenib in patients with HPS at 7 centers. A total of 28 patients with HPS were randomized to sorafenib 400 mg by mouth daily or a matching placebo in a 1:1 ratio. We found no statistically significant difference in the median change in AaPO₂ from baseline to 12 weeks between the patients allocated to sorafenib (4.5 mm Hg; IQR, -3.8 to 7.0 mm Hg) and those allocated to placebo (-2.4 mm Hg; IQR, -4.8 to 8.2 mm Hg; P = 0.70). There was also no difference between the groups in terms of degree of intrapulmonary shunting by contrast echocardiography. Sorafenib significantly reduced circulating levels of angiogenic markers, including vascular endothelial growth factor receptors (P < 0.01) and TIE2-expressing M2 monocytes (P = 0.03), but it reduced the mental component scores of the Short Form 36 (P = 0.04), indicating a worse quality of life. In conclusion, sorafenib did not change the AaPO₂ or other disease markers at 3 months in patients with HPS. Alternative antiangiogenic therapies or treatments targeting other pathways should be investigated.