Deleterious effect of nitric oxide inhibition in chronic hepatopulmonary syndrome

Hepatopulmonary syndrome after radiofrequency ablation of recurrent intrahepatic cholangiocarcinoma: a case report

Background

Radiofrequency ablation (RFA) is one of the definitive treatment modalities for liver cancer and has been increasingly used in the scenario of small-sized liver cancer. It is generally believed that RFA is minimally invasive and associated with a favorable safety profile in liver cancer patients. However, this interventional technique is subject to some morbidity in high-risk patients, such as those with complicating cirrhosis or a liver cancer located at a refractory segment.

Methods

Herein, we report the case of a middle-aged woman who developed acute liver failure with a complicating respiratory failure after RFA of recurrent intrahepatic cholangiocarcinoma.

Results

A diagnosis of hepatopulmonary syndrome was established. The patient was hospitalized in the intensive care unit for mechanical ventilation. Finally, the patient recovered from an eventful clinical course and survived free of recurrence until the last follow-up visit at 1 year after the discharge.

Conclusion

Our case report warns that hepatopulmonary syndrome, a less common morbidity secondary to liver cancer RFA, should require timely identification and appropriate management due to its life-threatening outcome.

Use of Methylene Blue to Treat Hypovolemic Shock Followed by Ischemia-Reperfusion Injury in the Postoperative Orthotopic Liver Transplant Patient: A Case Report

A 57-year-old female patient received elective liver transplant due to nonalcoholic steatohepatitis complicated by hepatocellular carcinoma. Her preoperative Model for End-Stage Liver Disease score was 11. The total transplant ischemic time was 10 hours and 35 minutes, and the warm ischemic time was 35 minutes. Even with aggressive fluid overload and use of high concentrations of vasoactive amines, the patient developed possible primary graft dysfunction with poor response to fluids and vasopressor support, suggesting vasoplegic syndrome. On the basis of the hypothesis of vasoplegic syndrome, the patient received methylene blue intravenously (100 mg bolus for 12 h/1.5 mg/kg). The catastrophic situation was controlled. The patient's urine output markedly improved, she was subsequently weaned from vasoactive support, and mechanical ventilation was discontinued 2 days later. The patient was discharged on the 20th postoperative day.

Proposed management algorithm for severe hypoxemia after liver transplantation in the hepatopulmonary syndrome

The hepatopulmonary syndrome (HPS) is defined as the triad of liver disease, intrapulmonary vascular dilatation, and abnormal gas exchange, and is found in 10-32% of patients with liver disease. Liver transplantation is the only known cure for HPS, but patients can develop severe posttransplant hypoxemia, defined as a need for 100% inspired oxygen to maintain a saturation of ≥85%. This complication is seen in 6-21% of patients and carries a 45% mortality. Its management requires the application of specific strategies targeting the underlying physiologic abnormalities in HPS, but awareness of these strategies and knowledge on their optimal use is limited. We reviewed existing literature to identify strategies that can be used for this complication, and developed a clinical management algorithm based on best evidence and expert opinion. Evidence was limited to case reports and case series, and we determined which treatments to include in the algorithm and their recommended sequence based on their relative likelihood of success, invasiveness, and risk. Recommended therapies include: Trendelenburg positioning, inhaled epoprostenol or nitric oxide, methylene blue, embolization of abnormal pulmonary vessels, and extracorporeal life support. Availability and use of this pragmatic algorithm may improve management of this complication, and will benefit from prospective validation.

Hepatopulmonary syndrome: the anaesthetic considerations

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 induces severe hypoxaemia. Considering the favourable long-term survival of HPS patients as well as the reversal of the syndrome with a functional liver graft, HPS is now an indication for orthotopic liver transplantation (OLT). Consequently, blood gas analysis and imaging techniques should be performed when cirrhotic patients present with shortness of breath as well as when OLT candidates are placed on the transplant waiting list. If the arterial partial pressure of oxygen (PaO2) is more than 10.7 kPa when breathing room air, HPS can be excluded and no other investigation is needed. When the PaO2 when breathing room air is 10.7 kPa or less, contrast-enhanced echocardiography should be performed to exclude pulmonary vascular dilatation. Lung function tests may also help detect additional pulmonary diseases that can contribute to impaired oxygenation. When contrast-enhanced echocardiography is negative, HPS is excluded and no follow-up is needed. When contrast-enhanced echocardiography is positive and PaO2 less than 8 kPa, patients should obtain a severity score that provides them with a reasonable probability of being transplanted within 3 months. In mild-to-moderate HPS (PaO2 8 to 10.6 kPa), periodic follow-up is recommended every 3 months to detect any further deterioration in PaO2. Although no intraoperative deaths have been directly attributed to HPS, oxygenation may worsen immediately following OLT due to volume overload and postoperative infections. Mechanical ventilation is often prolonged with an extended stay in the ICU. A high postoperative mortality (mostly within 6 months) is observed in this group of patients in comparison to non-HPS patients. However, the recovery of an adequate PaO2 within 12 months after OLT explains the similar outcome of HPS and non-HPS patients following OLT over a longer time period.

Cirrhosis and its complications: Evidence based treatment

Cirrhosis results from progressive fibrosis and is the final outcome of all chronic liver disease. It is among the ten leading causes of death in United States. Cirrhosis can result in portal hypertension and/or hepatic dysfunction. Both of these either alone or in combination can lead to many complications, including ascites, varices, hepatic encephalopathy, hepatocellular carcinoma, hepatopulmonary syndrome, and coagulation disorders. Cirrhosis and its complications not only impair quality of life but also decrease survival. Managing patients with cirrhosis can be a challenge and requires an organized and systematic approach. Increasing physicians’ knowledge about prevention and treatment of these potential complications is important to improve patient outcomes. A literature search of the published data was performed to provide a comprehensive review regarding the management of cirrhosis and its complications.

The relationship between hepatopulmonary syndrome and altitude

BACKGROUND

In a previous small retrospective study, the authors reported that hepatopulmonary syndrome was less common among liver transplant candidates at high-altitude centres compared with low-altitude centres.

OBJECTIVE

To further explore the relationship between hepatopulmonary syndrome and altitude of residence in a larger patient cohort.

METHODS

A cohort of 65,264 liver transplant candidates in the Organ Procurement and Transplantation Network liver database between 1988 and 2006 was analyzed. Hepatopulmonary syndrome diagnosis was determined during a comprehensive evaluation at a liver transplant centre by physicians who were experienced in the diagnosis and treatment of hepatopulmonary syndrome. The altitude of residence was determined for each patient by assigning the mean altitude of the zip code of residence at the time of entry on the wait list. Mean zip code elevation was calculated using the National Elevation Dataset of the United States Geological Survey, which provides exact elevation measurements across the entire country.

RESULTS

Hepatopulmonary syndrome was significantly less common at higher resident altitudes (P=0.015). After adjusting for age, sex and Model for End-Stage Liver Disease score, there was a 46% decrease in the odds of hepatopulmonary syndrome with every increase of 1000 m of resident elevation (OR 0.54 [95% CI 0.33 to 0.89]).

CONCLUSION

There was a negative association between altitude and hepatopulmonary syndrome. One plausible explanation is that the lower ambient oxygen found at higher elevation leads to pulmonary vasoconstriction, which mitigates the primary physiological lesion of hepatopulmonary syndrome, namely, pulmonary vasodilation.

Diverse effects of a low dose supplement of lipidated curcumin in healthy middle aged people

Background

Curcumin extracts of turmeric are proposed to produce health benefits. To date, human intervention studies have focused mainly on people with existing health problems given high doses of poorly absorbed curcumin. The purpose of the current study was to check whether in healthy people, a low dose of a lipidated curcumin extract could alter wellness-related measures.

Methods

The present study was conducted in healthy middle aged people (40–60 years old) with a low dose of curcumin (80 mg/day) in a lipidated form expected to have good absorption. Subjects were given either curcumin (N = 19) or placebo (N = 19) for 4 wk. Blood and saliva samples were taken before and after the 4 weeks and analyzed for a variety of blood and saliva measures relevant to health promotion.

Results

Curcumin, but not placebo, produced the following statistically significant changes: lowering of plasma triglyceride values, lowering of salivary amylase levels, raising of salivary radical scavenging capacities, raising of plasma catalase activities, lowering of plasma beta amyloid protein concentrations, lowering of plasma sICAM readings, increased plasma myeloperoxidase without increased c-reactive protein levels, increased plasma nitric oxide, and decreased plasma alanine amino transferase activities.

Conclusion

Collectively, these results demonstrate that a low dose of a curcumin-lipid preparation can produce a variety of potentially health promoting effects in healthy middle aged people.

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.

Methylene blue: potential use of an antique molecule in vasoplegic syndrome during cardiac surgery

Vasoplegic syndrome is a common complication of cardiopulmonary bypass, appearing with an incidence ranging between 5 and 25%. It is characterized by significant hypotension, high or normal cardiac output and low systemic vascular resistance. This syndrome is hypothesized to be caused by the inflammation-mediated dysregulation of endothelial homeostasis and subsequent endothelial dysfunction. In vasoplegic syndrome, the inhibition of the nitric oxide/cyclic guanosine monophosphate pathway with concomitant administration with traditional ionotropes may represent a promising therapeutic option. Methylene blue, an inhibitor of nitric oxide synthase and guanylate cyclase, may contribute to the improvement of refractory hypotension associated with endothelial dysfunction in vasoplegia. In this article, we will update evidence on the potential therapeutic use of methylene blue in vasoplegic syndrome.

Effects of caffeic acid phenethyl ester (CAPE) on hepatopulmonary syndrome

The aim of this study was to investigate the effects of caffeic acid phenethyl ester (CAPE) on inflammatory and related histopathological changes in the lung and liver in experimental hepatopulmonary syndrome (HPS) model. Forty Sprague Dawley rats were used in this study. The animals were divided into four groups of ten rats each. Group 1 and 2 was subjected the common bile duct (CBD) but not ligated, Group 3; (cirrhosis + saline): the CBD was ligated and was given intraperitoneal saline infusion treatment during 5 weeks. Group 4; (cirrhosis + CAPE): the CBD was ligated and was given intraperitoneal CAPE infusion treatment during 5 weeks. A 5-week waiting period was observed for the development of cirrhosis and the rats' lungs and liver were taken for histopathological examination. The induction of HPS resulted in a significant increase in serum bilurubin, AST, ALT, and NO levels, and decrease PO2 and O2 saturation. The use of CAPE significant decrease these parameters. Histopathological examination revealed less congestion, portal inflammation, and nodular formations of the liver, and less congestion, emphysematous and inflammatory changes and smallest perialviolar vascular diameters, in the lung in the cirrhosis + CAPE groups than in the other groups. CAPE treatment may be a potential approach for the treatment of hepatopulmonary syndrome in the future.

Effect of chronic methylene blue administration on hypoxemia in rats with common bile duct ligation

AIM

Acute administration of methylene blue (MB) can reverse hypoxemia in patients with hepatopulmonary syndrome (HPS). We evaluated the effect of chronic MB administration in common bile duct-ligated rats, which develop HPS by 5 weeks after surgery.

METHODS

A total of 96 Sprague-Dawley rats were used, including 63 rats with common bile duct ligation (CBDL), 22 sham-operated rats and 11 normal control rats. MB (6 mg/kg) was injected s.c. once a day for 4 weeks. Evaluation of hemodynamics and intrapulmonary vascular dilatation (IPVD), as well as blood sampling for arterial blood gas analysis, were done under conscious and unrestrained conditions. Hemodynamics were assessed by the reference sample method using (141)Ce-microspheres (15 microm in diameter), and IPVD was also determined by i.v. injection of these microspheres. Histological examination of the lungs was done with hematoxylin-eosin staining and immunohistochemical staining for von Willebrand factor or vascular endothelial growth factor.

RESULTS

Both the arterial oxygen tension and alveolar-arterial oxygen difference were significantly improved in MB-treated CBDL rats. The hyperdynamic circulation and splanchnic hyperemia seen in untreated CBDL rats were also alleviated by MB treatment. However, IPVD was not affected by MB. Histological examination of the lungs indicated that MB treatment reduced the proliferation of alveolar capillary vessels and angiogenesis, leading to improvement of arterial dysoxygenation. Hepatic synthetic and detoxification functions, as well as renal function, were not altered by MB treatment.

CONCLUSION

Methylene blue may be a candidate treatment for HPS that does not cause deterioration of hepatic or renal function.

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.

Deficiency of mitogen-activated protein kinase phosphatase-1 results in iNOS-mediated hypotension in response to low-dose endotoxin

Mitogen-activated protein kinase phosphatase-1 (MKP-1) is essential in limiting the proinflammatory response to lipopolysaccharide (LPS). We hypothesized that Mkp-1(-/-) mice would respond to low-dose LPS with a fall in blood pressure due to augmented expression of inducible nitric oxide (NO) synthase (iNOS). To test this hypothesis, Mkp-1(-/-) mice and their wild-type littermates were treated with 10 microg/kg iv LPS, and mean arterial blood pressure (MAP) and exhaled NO production (exNO) were measured. Tissues were harvested for an assessment of iNOS protein levels. Wild-type mice had no change in MAP or exNO during the experimental period, whereas Mkp-1(-/-) mice had a fall (P < 0.005) in MAP [79 +/- 5% of baseline (BL)] and an increase (P < 0.01) in exNO (266 +/- 50% of BL) after 150 min. The tissue levels of iNOS were greater in Mkp-1(-/-) than in wild-type mice. In additional experiments, 60 min after LPS treatment, Mkp-1(-/-) and wild-type mice were given N(omega)-nitro-l-arginine methyl ester (l-NAME) or aminoguanidine, and MAP and exNO were monitored for 90 min. Treatment with l-NAME prevented the LPS-induced increase in exNO and decrease in MAP but resulted in decreased exNO and elevated MAP in wild-type mice. Aminoguanidine prevented the increase in exNO and the fall in MAP caused by LPS in Mkp-1(-/-) mice, without significantly affecting MAP or exNO in wild-type mice. These results demonstrate that a deficiency of MKP-1 results in an exaggerated hypotensive response to LPS mediated by augmented iNOS expression. We speculate that defects in the Mkp-1 gene may increase susceptibility for the development of septic shock.

Intestinal endotoxemia plays a central role in development of hepatopulmonary syndrome in a cirrhotic rat model induced by multiple pathogenic factors

AIM: To characterize the correlation between severity of hepatopulmonary syndrome (HPS) and degree of hepatic dysfunction, and to explore how intestinal endotoxemia (IETM) affects the development of HPS in cirrhotic rats.

METHODS: Male Wister rats were fed with a diet containing maize flour, lard, cholesterol, and alcohol and injected subcutaneously with CCl₄ oil solution every two days for 8 wk to induce typical cirrhosis and development of HPS. The animals were also given a nitric oxide (NO) production inhibitor, N^ω-nitro-L-arginine methyl ester (L-NAME) intraperitoneally, and an iNOS inhibitor, aminoguanidine hydrochloride (AG) via gavage daily from the end of the 4th wk to the end of the 6th or 8th wk, or a HO-1 inhibitor, zinc protoporphyrin (ZnPP) intraperitoneally 12 h prior to killing. Blood, liver and lung tissues were sampled.

RESULTS: Histological deterioration of the lung paralleled to that of the liver in the cirrhotic rats. The number of pulmonary capillaries was progressively increased from 6.1 ± 1.1 (count/filed) at the 4th wk to 14.5 ± 2.4 (count/filed) at the 8th wk in the cirrhotic rats. Increased pulmonary capillaries were associated with increased blood levels of lipopolysaccharide (LPS) (0.31 ± 0.08 EU/mL vs control 0.09 ± 0.03 EU/mL), alanine transferase (ALT, 219.1 ± 17.4 U/L vs control 5.9 ± 2.2 U/L) and portal vein pressure. Compared with normal control animals, the number of total cells in bronchoalveolar lavage fluid (BALF) of the cirrhotic rats at the 8th wk was not changed, but the number of macrophages and the ratio of macrophages to total cells were increased by nearly 2-fold, protein expression of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) started to increase significantly at the 4th wk, and reached its peak at the 8th wk in the lung of cirrhotic rats. The increase of iNOS expression appeared to be quicker than that of eNOS. NO₂^-/NO₃^- was also increased, which was correlated to the increase of iNOS (r = 0.7699, P < 0.0001) and eNOS (r = 0.5829, P < 0.002). mRNA expression of eNOS and iNOS was highly consistent with their protein expression.

CONCLUSION: Progression and severity of HPS as indicated by both increased pulmonary capillaries and histological changes are closely associated with LPS levels and progression of hepatic dysfunction as indicated by increased levels of ALT and portal vein pressure. Intestinal endotoxemia plays a central role in the development of HPS in the cirrhotic rat model by inducing NO and/or CO.

Therapy Insight: hepatopulmonary syndrome and orthotopic liver transplantation

Hepatopulmonary syndrome (HPS)--a pulmonary complication observed in patients who have chronic liver disease and/or portal hypertension--is attributed to intrapulmonary vascular dilatation and induces severe hypoxemia. HPS is mainly detected when patients are included on the waiting list for orthotopic liver transplantation (OLT) and can be diagnosed by blood gas analysis, transthoracic contrast-enhanced echocardiography or body scan with (99m)Tc-labeled macroaggregated albumin perfusion. When the partial pressure of arterial oxygen (PaO(2)) is >or=80 mmHg, it is unlikely that the patient has HPS. When the PaO(2) is <80 mmHg, imaging techniques should be used to confirm or exclude pulmonary vascular dilatation. When a diagnosis of HPS is confirmed, knowing the degree of hypoxemia is crucial for optimum patient management. Patients who have a PaO(2) >or=50 mmHg but <60 mmHg should be prioritized for OLT. This procedure is not indicated for patients with a PaO(2) between 60 mmHg and 80 mmHg, although follow-up every 3 months is recommended to detect any deterioration of the PaO(2). A PaO(2) of <50 mmHg might preclude OLT, because mortality and morbidity after OLT are greatly increased in these patients.