Cost-effectiveness of screening for hepatopulmonary syndrome in liver transplant candidates

Correlation between hepatopulmonary syndrome and oxygen saturation pulse oximetry in cirrhotic patients

OBJECTIVE

Hepatopulmonary Syndrome (HPS) is a complication of cirrhosis that worsens the disease's prognosis, pre and post liver transplant. The objective of this study is to analyze the prevalence of HPS in cirrhotic patients at our service and to correlate it with oxygen saturation (SatO2) using a pulse oximeter to evaluate if this is useful as a screening test for HPS. A prospective study was conducted in patients with hepatic cirrhosis conventionally selected from 2014 to 2016. All the patients underwent an echocardiogram with microbubbles and oxygen saturation measurement by pulse oximetry. Those with intrapulmonary shunt were submitted to arterial blood gas analysis. The relationship between oxygen saturation and HPS was assessed by the multivariate model of binary logistic regression. We analyzed 77 patients, and 23.3% (18 patients) had all criteria for HPS. The relationship between HPS and SatO2 did not show statistical significance, even after the variables were adjusted for sex, age, and smoking. Oxygen saturation alone was not able to detect HPS in the sample of cirrhotic patients. More accurate methods for screening and diagnosis of the syndrome should be used.

Resources Utilization After Liver Transplantation in Patients With and Without Hepatopulmonary Syndrome: Cleveland Clinic Experience

Patients with hepatopulmonary syndrome (HPS) reportedly experience posttransplant morbidity and require more resources to care during perioperative period. The exact incremental increase of resources utilization compared with non-HPS population remains unknown.

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.

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

Screening for hepatopulmonary syndrome (HPS) using pulse oximetry is recommended in liver transplant (LT) candidates because mortality is increased, independently of the severity of the oxygenation defect. LT exception points may be afforded to those with HPS and severe hypoxemia. We assessed the screening characteristics of pulse oximetry for HPS. The Pulmonary Vascular Complications of Liver Disease 2 study is a multicenter, prospective cohort study of adults undergoing their first LT evaluation. Patients underwent protocolized assessment of oxygen saturation by pulse oximetry (SpO₂ ), arterial blood gas, spirometry, and contrast-enhanced echocardiography (CE). HPS was defined as an alveolar-arterial gradient ≥15 mm Hg (≥20 mm Hg if age >64 years), intrapulmonary vascular dilatation on CE, and absence of lung disease. The study sample included 363 patients. Of these, 75 (20.7%; 95% confidence interval [CI], 16.6%-25.2%) met the criteria for HPS. The area under the receiver operating characteristic curve (or c-statistic) for SpO₂ in discriminating HPS was 0.59 (95% CI, 0.51-0.66). An SpO₂ <96%, recommended by practice guidelines as a threshold to require further testing, had low sensitivity (28%; 95% CI, 18%-28%). The c-statistic of SpO₂ in discriminating HPS with a partial pressure of oxygen (PaO₂ ) <60 mm Hg (eligible for LT exception points) was 0.76 (95% CI, 0.46-1.00). An SpO₂ cutoff of <96% had higher sensitivity for detecting HPS with PaO₂ <60 mm Hg (71%; 95% CI, 38%-100%) but was still inadequate. Conclusion: Pulse oximetry is not sufficiently sensitive to screen for HPS in LT candidates. Arterial blood gas and CE are required in LT candidates for diagnosis of HPS.

International Liver Transplant Society Practice Guidelines: Diagnosis and Management of Hepatopulmonary Syndrome and Portopulmonary Hypertension. Transplantation. 2016;100:1440-1452. [PMID: 27326810 DOI: 10.1097/tp.0000000000001229]

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.

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

Hepatopulmonary syndrome: What we know and what we would like to know

Hepatopulmonary syndrome (HPS) is characterized by abnormalities in blood oxygenation caused by the presence of intrapulmonary vascular dilations (IPVD) in the context of liver disease, generally at a cirrhotic stage. Knowledge about the subject is still only partial. The majority of the information about the etiopathogenesis of HPS has been obtained through experiments on animals. Reported prevalence in patients who are candidates for a liver transplantation (LT) varies between 4% and 32%, with a predominance of mild or moderate cases. Although it is generally asymptomatic it does have an impact on their quality of life and survival. The diagnosis requires taking an arterial blood gas sample of a seated patient with alveolar-arterial oxygen gradient (AaO₂) ≥ 15 mm Hg, or ≥ 20 mm Hg in those over 64 years of age. The IPVD are identified through a transthoracic contrast echocardiography or a macroaggregated albumin lung perfusion scan (^99mTc-MAA). There is currently no effective medical treatment. LT has been shown to reverse the syndrome and improve survival rates, even in severe cases. Therefore the policy of prioritizing LT would appear to increase survival rates. This paper takes a critical and clinical look at the current understanding of HPS, as well as the controversies surrounding it and possible future research.

Hepatopulmonary Syndrome

Hepatopulmonary syndrome (HPS) is a pulmonary complication observed in patients with chronic liver disease and/or portal hypertension, attributable to an intrapulmonary vascular dilatation that may induce severe hypoxemia. Microvascular dilation and angiogenesis in the lung have been identified as pathologic features that drive gas exchange abnormalities in experimental HPS. Pulse oximetry is a useful screening test for HPS, which can guide subsequent use of arterial blood gases. Contrast-enhanced echocardiography, perfusion lung scanning, and pulmonary arteriography are three currently used diagnostic imaging modalities that identify the presence of intrapulmonary vascular abnormalities. The presence of HPS increases mortality and impairs quality of life, but is reversible with liver transplantation. No medical therapy is established as effective for HPS. At the present time, liver transplantation is the only available treatment for HPS.

Hepatopulmonary syndrome

The hepatopulmonary syndrome (HPS) is a pulmonary complication of cirrhosis and/or portal hypertension whereby patients develop hypoxemia as a result of alterations in pulmonary microvascular tone and architecture. HPS occurs in up to 30% of patients with cirrhosis. Although the degree of hypoxemia does not reliably correlate with the severity of liver disease, patients with HPS have a higher mortality than do patients with cirrhosis without the disorder. There has been progress into defining the mechanisms that lead to hypoxemia in HPS, but to date there are no therapeutic options for HPS aside from liver transplantation.

Pulse oximeter oxygen saturation in prediction of arterial oxygen saturation in liver transplant candidates

BACKGROUND

Liver transplant is the only definitive treatment for many patients with end stage liver disease. Presence and severity of preoperative pulmonary disease directly affect the rate of postoperative complications of the liver transplantation. Arterial blood gas (ABG) measurement, performed in many transplant centers, is considered as a traditional method to diagnose hypoxemia. Because ABG measurement is invasive and painful, pulse oximetry, a bedside, noninvasive and inexpensive technique, has been recommended as an alternative source for the ABG measurement.

OBJECTIVES

The aim of this study was to evaluate the efficacy of pulse oximetry as a screening tool in hypoxemia detection in liver transplant candidates and to compare the results with ABGs.

PATIENTS AND METHODS

Three hundred and ninety transplant candidates (237 males and 153 females) participated in this study. Arterial blood gas oxyhemoglobin saturation (SaO2) was recorded and compared with pulse oximetry oxyhemoglobin saturation (SpO2) results for each participants. The area under the curve (AUC) of receiver operating characteristic (ROC) curves was calculated by means of nonparametric methods to evaluate the efficacy of pulse oximetry to detect hypoxemia.

RESULTS

Roc-derived SpO2 threshold of ≤ 94% can predict hypoxemia (PaO2 < 60 mmHg) with a sensitivity of 100% and a specificity of 95%. Furthermore, there are associations between the ROC-derived SpO2 threshold of ≤ 97% and detection of hypoxemia (PaO2 < 70 mmHg) with a sensitivity of 100% and a specificity of 46%. The accuracy of pulse oximetry was not affected by the severity of liver disease in detection of hypoxemia.

CONCLUSIONS

Provided that SpO2 is equal to or greater than 94%, attained from pulse oximetry can be used as a reliable and accurate substitute for the ABG measurements to evaluate hypoxemia in patients with end stage liver disease.

Pulmonary complications in chronic liver disease

The association of chronic liver disease with respiratory symptoms and hypoxia is well recognized. Over the last century, three pulmonary complications specific to chronic liver disease have been characterized: hepatopulmonary syndrome (HPS), portopulmonary hypertension (POPH), and hepatic hydrothorax (HH). The development of portal hypertension is fundamental in the pathogenesis of each of these disorders. HPS is the most common condition, found in 5%-30% of cirrhosis patients, manifested by abnormal oxygenation due to the development of intrapulmonary vascular dilatations. The presence of HPS increases mortality and impairs quality of life, but is reversible with liver transplantation (LT). POPH is characterized by development of pulmonary arterial hypertension in the setting of portal hypertension, and is present in 5%-10% of cirrhosis patients evaluated for LT. Screening for POPH in cirrhosis patients eligible for LT is critical since severe POPH is a relative contraindication for LT. Patients with moderate POPH, who respond adequately to medical therapy, may benefit from LT, although sufficient controlled data are lacking. HH is a transudative pleural effusion seen in 5%-10% of cirrhosis patients, in the absence of cardiopulmonary disease. Diagnosis of HH should prompt consideration for LT, which is the ultimate treatment for HH. Conservative management includes salt restriction and diuretics, with thoracentesis and transjugular intrahepatic portosystemic shunt (TIPS) as second-line therapeutic options.

Pulmonary vascular complications in portal hypertension and liver disease: a concise review

Chronic liver disease and/or portal hypertension may be associated with one of the two pulmonary vascular complications: portopulmonary hypertension and hepatopulmonary syndrome. These pulmonary vascular disorders are notoriously underdiagnosed; however, they have a substantial negative impact on survival and require special attention in order to understand their diagnostic approach and to select the best therapeutic options. Portopulmonary hypertension results from excessive vasoconstriction, vascular remodeling, and proliferative and thrombotic events within the pulmonary circulation that lead to progressive right ventricular failure and ultimately to death. On the other hand, abnormal intrapulmonary vascular dilations, profound hypoxemia, and a wide alveolar-arterial gradient are the hallmarks of the hepatopulmonary syndrome, resulting in difficult-to-treat hypoxemia. The aim of this review is to summarize the latest pathophysiologic concepts, diagnostic approach, therapy, and prognosis of portopulmonary hypertension and hepatopulmonary syndrome, as well as to discuss the role of liver transplantation as a definitive therapy in selected patients with these conditions.

Pentoxifylline in hepatopulmonary syndrome

AIM: To determine the effects of pentoxifylline (PTX) on clinical manifestations and evaluate arterial blood gas data in hepatopulmonary syndrome (HPS) in children.

METHODS: In a pilot study of 10 children with chronic liver disease, who had HPS, 20 mg/kg/d PTX was administered for 3 mo. Clinical data and arterial blood gas parameters were evaluated at baseline, the end of the treatment period, and 3 mo after drug discontinuation.

RESULTS: Six patients could tolerate PTX, while four patients experienced complications. Among patients who could tolerate PTX, there was a significant increase in arterial oxygen pressure (PaO₂) (P = 0.02) and oxygen saturation (SaO₂) (P = 0.04) and alveolar-arterial oxygen gradient (P = 0.02) after 3 mo of treatment. Significant decreases in PaO₂ (P = 0.02) and alveolar-arterial oxygen gradient (P = 0.02) were also seen after drug discontinuation.

CONCLUSION: PTX may improve PaO₂, SaO₂ and alveolar-arterial oxygen gradient in the early stage of HPS.

Hepatopulmonary syndrome: update on pathogenesis and clinical features

Hepatopulmonary syndrome (HPS) is a serious vascular complication of liver disease that occurs in 5-32% of patients with cirrhosis. The presence of HPS markedly increases mortality. No effective medical therapies are currently available and liver transplantation is the only established treatment option for HPS. The definition and diagnosis of HPS are established by the presence of a triad of liver disease with intrapulmonary vascular dilation that causes abnormal arterial gas exchange. Experimental biliary cirrhosis induced by common bile duct ligation in the rat reproduces the pulmonary vascular and gas exchange abnormalities of human HPS and serves as a pertinent animal model. Pulmonary microvascular dilation and angiogenesis are two central pathogenic features that drive abnormal pulmonary gas exchange in experimental HPS, and thus might underlie HPS in humans. Defining the mechanisms involved in the microvascular alterations of HPS has the potential to lead to effective medical therapies. This Review focuses on the current understanding of the pathogenesis, clinical features and management of HPS.

Evolution of gas exchange abnormalities in patients with liver cirrhosis candidate for liver transplantation

BACKGROUND

Hypoxemia is common in patients with cirrhosis but the natural history of this syndrome is unknown. This study was conducted to evaluate the natural history of arterial oxygenation in patient with end stage liver cirrhosis.

METHODS

Sixty eight patients with liver cirrhosis were followed up for 6-12 months. Arterial blood gas (ABG) and pulse oximetry were obtained on day of presentation and follow up.

RESULTS

There were no significant changes in the oxygen saturation by pulse oximetry (SpO2), partial pressure of oxygen (PaO2) and alveolar arterial oxygen gradient (A-a O2) after 6-12 months. Mean arterial oxygen saturation (SaO2) in 46 patients was 95.42±1.92, and after follow up changed to 95.45±2.96. Thirty eight patients had SaO2 > 94% (mean 96.12±1.08 after 6-12 months changed to 95.66±2.58) ; 8 patients had SaO2 = 94 (mean 92.08±1.44 after 6-12 months changed to 94.46±4.47).

CONCLUSION

There were no significant changes in the SpO2, PaO2 and A-a O2 after 6-12 months.

Pulmonary dysfunction and hepatopulmonary syndrome in cirrhosis and portal hypertension

BACKGROUND

Pulmonary dysfunction including the hepatopulmonary syndrome (HPS) is an important complication to cirrhosis and portal hypertension. However, the precise relation to liver dysfunction and the prevalence of HPS are unclear.

AIMS

We therefore aimed to assess (i) the prevalence of HPS in consecutive alcoholic cirrhotic patients, (ii) the degree of pulmonary dysfunction in relation to liver function and (iii) the response of a 100% oxygen test on cardiopulmonary and peripheral oxygenation.

METHODS

Fifty patients with cirrhosis and 12 matched healthy controls were entered in this study. All underwent haemodynamic and pulmonary investigations [lung diffusing capacity for carbon monoxide (DLCO), contrast-enhanced echocardiography and detection of extrapulmonary shunt fraction]. A 100% oxygen test was performed with the assessment of arterial oxygen tension (PaO(2)), the alveolar-arterial oxygen gradient (AaPO(2)) and peripheral transcutaneous oxygen tension (tcPO(2)).

RESULTS

The prevalence of HPS was 10%. PaO(2) and DLCO were reduced in 32 and 72% and AaPO(2), was increased in 60% of the patients respectively. DLCO correlated with indicators of liver dysfunction (galactose elimination capacity, P<0.01, indocyanine green clearance, P<0.001), portal hypertension (post-sinusoidal resistance, P<0.01) and central hypovolaemia (central and arterial blood volume, P<0.01). After 100% oxygen inhalation, the changes in PaO(2), AaPO(2), tcPO(2) and heart rate were abnormal in the patients compared with controls (P<0.02).

CONCLUSIONS

Pulmonary dysfunction in alcoholic cirrhosis is common and relates to different aspects of liver dysfunction, whereas the prevalence of HPS is low. The haemodynamic response to oxygen inhalation is clearly impaired and HPS and pulmonary dysfunction seem to be caused by different pathophysiological mechanisms.

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.