New therapeutic strategy with extracorporeal membrane oxygenation for refractory hepatopulmonary syndrome after liver transplant: A case report

BACKGROUND Due to the lack of published literature about treatment of refractory hepatopulmonary syndrome(HPS)after liver transplant(LT),this case adds information and experience on this issue along with a treatment with positive outcomes.HPS is a complication of end-stage liver disease,with a 10%-30%incidence in cirrhotic patients.LT can reverse the physiopathology of this process and restore normal oxygenation.However,in some cases,refractory hypoxemia persists,and extracorporeal membrane oxygenation(ECMO)can be used as a rescue therapy with good results.CASE SUMMARY A 59-year-old patient with alcohol-related liver cirrhosis and portal hypertension was included in the LT waiting list for HPS.He had good liver function(Model for End-Stage Liver Disease score 12,Child-Pugh class B7).He had pulmonary fibrosis and a mild restrictive respiratory pattern with a basal oxygen saturation of 82%.The macroaggregated albumin test result was>30.Spirometry demonstrated a forced expiratory volume in one second(FEV1)of 78%,forced vital capacity(FVC)of 74%,FEV1/FVC ratio of 81%,diffusion capacity for carbon monoxide of 42%,and carbon monoxide transfer coefficient of 57%.He required domiciliary oxygen at 2 L/min(16 h/d).The patient was admitted to the intensive care unit(ICU)and extubated in the first 24 h,needing high-flow therapy and non-invasive ventilation and inhaled nitric oxide afterwards.Reintubation was needed after 72 h.Due to the non-response to supportive therapies,installation of ECMO was decided with progressive recovery after 9 d.Extubation was possible on the tenth day,maintaining a high-flow nasal cannula and de-escalating to conventional oxygen therapy after 48 h.He was discharged from ICU on postoperative day(POD)20 with a 90%-92%oxygen saturation.Steroid recycling was needed twice for acute rejection.The patient was discharged from hospital on POD 27 with no symptoms,with an 89%-90%oxygen saturation.CONCLUSION Due to the favorable results observed,ECMO could become the central axis of treatment of HPS and refractory hypoxemia after LT.

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,Nω-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.

Experimental study on the role of endotoxin in the development of hepatopulmonary syndrome

AIM: To evaluate the role of intestinal endotoxemia in the genesis of hepatopulmonary syndrome. METHODS: A rat model of cirrhosis was prepared with the method of compound factors. At the end of the eighth week, rats with cirrhosis were treated with 300 μg LPS/100 g body weight, and 1 g/rat of glycine about four h prior to LPS. After three h of LPS treatment, blood and tissues were collected for various measurements. Kupffer cells were isolated from male Wistar rats and cultured, and divided into five groups. Supernatant was harvested at 3 h after treatment with LPS for measurement of tumor necrosis factor-alpha (TNF-α). RESULTS: Our results showed that in rats with cirrhosis, slowed and deepened breath with occasional pause was. PaO2, PaCO2 and standard bicarbonate (SB) in arterial blood were decreased. Arterial O2 and actual bicarbonate (AB) were markedly decreased. There was a close correlation between decreased O2 and endotoxin. Metabolic acidosis accompanying respiratory alkalosis was the primary type of acid-base imbalance. The alveolar-arterial oxygen gradient was sharply widened. Massive accumulation of giant macrophages in the alveolar spaces and its wall and widened alveolar wall architecture were observed. The number of bacterial translocations in mesenteric lymph nodes increased. The ratio of TC99M-MAA brain-over-lung radioactivity rose. Endotoxin, and TNF-α, endothelin-1 (ET-1), nitric oxide (NO) in plasma and ET-1, carbon monoxide (CO) in lung homogenates increased. After administration of a given dosage of LPS in rats with cirrhosis, various pathological parameters worsened. Plasma level of endotoxin was related to TNF-α, ET-1, NO in plasma and ET-1, NO, CO in lung homogenates. TNF-α level was related to ET-1 and NO in plasma and lung homogenates and CO in lung homogenate as well. The level of TNF-α increased after infusion of LPS into culture supernatant of Kupffer cells in vitro. However, TNF-α significantly decreased after pretreatment with glycine, PD98059 and SB212850. Glycine could antagonize the effect of LPS in vivo and in vitro. CONCLUSION: Intestinal endotoxemia accompanying by cirrhosis may be an important mechanism in the development of hepatopulmonary syndrome in rats. Overproduction of TNF-α due to endotoxin stimulation of Kupffer cells via mitogen-activated protein kinase (MAPK) signal transduction pathway may be a major mechanism mediating the pathologic alterations of hepatopulmonary syndrome.

Progress in investigating the pathogenesis of hepatopulmonary syndrome

BACKGROUND: The pathogenesis of hepatopulmonary syndrome is complicated and remains unknown. This review aims to provide an updated knowledge about the pathogenesis of the syndrome. DATA SOURCES: Five medical databases, MEDLINE, Science-Direct, OVID, Springer Link, and Wiley Inter Science were searched for articles on 'hepatopulmonary syndrome', 'cirrhosis', 'angiogenesis', 'intestinal endotoxemia', 'nitric oxide', 'carbon monoxide', and other related subjects. RESULTS: Currently, imbalance between vasodilation and vasoconstriction, intestinal bacterial translocation, intestinal endotoxemia, and activation of the lung monocyte/macrophage system may play important roles in the pathogenesis of hepatopulmonary syndrome. Recent studies found that angiogenesis is also an important factor in the pathogenesis of experimental hepatopulmonary syndrome. CONCLUSION: Angiogenesis inhibition may be a potential approach for the treatment of hepatopulmonary syndrome in the future.

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.

Effect of transjugular intrahepatic portosystemic shunt on pulmonary gas exchange in patients with portal hypertension and hepatopulmonary syndrome

AIM: To assess the impact of transjugular intrahepatic portosystemic shunt (TIPS) on pulmonary gas exchange and to evaluate the use of TIPS for the treatment of hepatopulmonary syndrome (HPS).METHODS: Seven patients, three of them with advanced HPS, in whom detailed pulmonary function tests were performed before and after TIPS placementat the University of Alabama Hospital and at the Hospital Clinic, Barcelona, were considered.RESULTS: TIPS patency was confirmed by hemodynamic evaluation. No changes in arterial blood gases were observed in the overall subset of patients. Transient arterial oxygenation improvement was observed in only one HPS patient, early after TIPS, but this was not sustained 4 mo later.CONCLUSION: TIPS neither improved nor worsened pulmonary gas exchange in patients with portal hypertension. This data does not support the use of TIPS as a specific treatment for HPS. However, it does reinforce the view that TIPS can be safely performed for the treatment of other complications of portal hypertension in patients with HPS.

Clinical features of hepatopulmonary syndrome in cirrhotic patients

AIM： To evaluate the frequency, clinical and paraclinical features of hepatopulmonary syndrome （HPS） and to determine their predictive values in diagnosis of this syndrome in patients in Iran. METHODS： Fifty four cirrhotic patients underwent contrast enhanced echocardiography to detect intrapulmonary and intracardiac shunts by two cardiologists. Arterial blood oxygen, 02 gradient （A-a） and orthodoxy were measured by arterial blood gas （ABG） test. The patients positive for diagnostic criteria of HPS were defined as clinical HPS cases and those manifesting the intrapulmonary arterial dilation but no other criteria （arterial blood hypoxemia） were defined as IHPS cases. HPS frequency, sensitivity, positive and negative predictive values of clinical and paraclinical features were studied. RESULTS： Ten （18.5%） and seven （13%） cases had clinical and subclinical HPS, respectively. The most common etiology was hepatitis B. Dyspnea （100%） and cyanosis （90%） were the most prevalent clinical features. Dyspnea and clubbing were the/host sensitive and specific clinical features respectively. No significant relationship was found between HPS and splenomegaly, ascites, edema, jaundice, oliguria, and collateral veins. HPS was more prevalent in hepatitis B. PaO2〈 70 and arterial-alveolar gradient had the highest sensitivity in HPS patients. Orthodoxy specificity was 100%. CONCLUSION： Clubbing with positive predictive value （PPV） of 75% and dyspnea with negative predictive value （NPV） of 75% are the best clinical factors in diagnosis of HPS syndrome. PaO2〈70 and P （A-a） 02〉 30 and their sum, are the most valuable negative and positive predictive values in HPS patients.

Protective effect of nitric oxide on hepatopulmonary syndrome from ischemia-reperfusion injury

AIM： To evaluate immunological protection of nitric ox- ide （NO） in hepatopulmonary syndrome and probable mechanisms of ischemia-reperfusion （IR） injury in rat liver transplantation, METHODS： Sixty-six healthy male Wistar rats were randomly divided into three groups （11 donor/recipi-ent pairs）. In group 11, organ preservation solution was lactated Ringer＇s solution with heparin 10 000/μL at 4℃. In groups I and 111, the pLeservation solution added, respectively, L-arginine or Ng-L-arginine methyl ester （L-NAME） （1 mmol/L） based on group 11, and recipients were injected with L-arginine or L-NAME （50 mg/kg） in the anhepatic phase. Grafted livers in each group were stored for 6 h and implanted into recipi- ents. Five rats were used for observation of postopera- tive survival in each group. The other six rats in each group were used to obtain tissue samples, and execut- ed at 3 h and 24 h after transplantation. The levels of alanine aminotransferase （ALT）, tumor necrosis factor （TNF）-a and NO metabolites （NOx） were detected, and expression of NO synthase, TNF-α and intercellular adhesion molecule 1 （ICAM-1） was examined by tri- phosphopyridine nucleotide diaphorase histochemical and immunohistochemical staining. RESULTS： By supplementing L-arginine to strengthen the NO pathway, a high survival rate was achieved and hepatic function was improved. One-week sur- viral rate of grafted liver recipients in group I was significantly increased （28.8 4±36.6 d ys 4 4±1.7 d, P 〈 0.01） as compared with groups 11 and Ill. Serum levels of ALT in group ] were 2-7 times less than those in groups 11 and 11I （P 〈 0.01）. The cyclic guanosine monophosphate （cGMP） levels in liver tissue and NOx in group I were 3-4 times higher than those of group 11 after 3 h and 24 h reperfusion, while in group ]]], they were significantly reduced as compared with those in group ]1 （P 〈 0.01）. The levels of TNF-（z in group I were significantly lower than in group Ⅱ after 3 h and 24 h reperfusion （P 〈 0.01）, while being sig- nificantly higher in group Ⅲ than group Ⅱ （P 〈 0.01）. Histopathology revealed more severe tissue damage in graft liver and lung tissues, and a more severe in- flammatory response of the recipient after using NO synthase inhibitor, while the pathological damage to grafted liver and the recipient＇s lung tissues was signifi-cantly reduced in group I after 3 h and 24 h reperfu- sion. A small amount of constitutive NO synthase （cNOS） was expressed in liver endothelial cells after 6 h cold storage, but there was no expression of inducible NO synthase （iNOS）. Expression of cNOS was particularly significant in vascular endothelial cells and liver cells at 3 h and 24 h after reperfusion in group Ⅱ but expres- sion of iNOS and ICAM-1 was low in group I. There was diffuse strong expression of ICAM-1 and TNF-α in group Ⅱ at 3 h after reperfusion. CONCLUSION： The NO/cGMP pathway may be critical in successful organ transplantation, especially in treat- ing hepatopulmonary syndrome during cold IR injury in rat orthotopic liver transplantation.

Portopulmonary hypertension and hepatopulmonary syndrome

Portopulmonary hypertension (POPH) and hepatopulmonary syndrome (HPS) are two frequent complications of liver disease, with prevalence among liver transplant candidates of 6% and 10%, respectively. Both conditions result from a lack of hepatic clearance of vasoactive substances produced in the splanchnic territory. Subsequently, these substances cause mainly pulmonary vascular remodeling and some degree of vasoconstriction in POPH with resulting elevated pulmonary pressure and right ventricular dysfunction. In HPS the vasoactive mediators cause intrapulmonary shunts with hypoxemia. Medical treatment is disappointing overall. Whereas liver transplantation (LT) results in the disappearance of HPS within six to twelve months, its effect on POPH is highly unpredictable. Modern strategies in managing HPS and POPH rely on a thorough screening and grading of the disease&#x02019;s severity, in order to tailor the appropriate therapy and select only the patients who will benefit from LT. The anesthesiologist plays a central role in managing these high-risk patients. Indeed, the important hemodynamic and respiratory modifications of the perioperative period must be avoided through continuation of the preoperatively initiated drugs, appropriate intraoperative monitoring and proper hemodynamic and respiratory therapies.

Effect of oral garlic on arterial oxygen pressure in children with hepatopulmonary syndrome

AIM： To study the effect of oral garlic on arterial oxygen pressure in children with hepatopulmonary syndrome, METHODS： Garlic powder in a capsule form was given to 15 children with hepatopulmonary syndrome （confirmed by contrast echocardiography） at the dosage of 1 g/1.73 m^2 per day. Patients were evaluated clinically and by arterial blood gas every four weeks. RESULTS： The garlic capsule was administered to 15 patients with hepatopulmonary syndrome. There were 10 boys and 5 girls with a mean age of 9.4 ± 3.9 years. The underlying problems were biliary tract atresia （4 patients）, autoimmune hepatitis （4 patients）, cryptogenic cirrhosis （4 patients） and presinusoidal portal hypertension （3 patients）. Eight patients （53.3%） showed an increase of 10 mmHg in their mean arterial oxygen pressure. The baseline PaO2 was 65.6 ± 12.1 mmHg in the responder group and 47.1 ± 11.2 mmHg in nonresponder group. At the end of treatment the mean PaO2 in responders and non-responders was 92.2 ± 7.75 mmHg and 47.5 ± 11.87 mmHg, respectively （P 〈 0.01）. CONCLUSION： Garlic may increase oxygenation and improve dyspnea in children with hepatopulmonary syndrome.

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 chil- dren. METHODS： In a pilot study of 10 children with chronic liver disease, who had HPS, 20 mg/kg/d PTX was ad- ministered 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 oxy- gen saturation （Sa02） （P = 0.04） and alveolar-arterial oxygen gradient （P = 0.02） after 3 mo of treatment. Significant decreases in Pa02 （P = 0.02） and alveolararterial oxygen gradient （P = 0.02） were also seen after drug discontinuation. CONCLUSION： PTX may improve PaO2, Sa02 and alve- olar-arterial oxygen gradient in the early stage of HPS.

Growth hormone cocktail improves hepatopulmonary syndrome secondary to hypopituitarism:A case report

BACKGROUND Metabolic associated fatty liver disease frequently occurs in patients with hypopituitarism and growth hormone(GH)deficiency.Some patients may develop to hepatopulmonary syndrome(HPS).HPS has a poor prognosis and liver transplantation is regarded as the only approach to cure it.CASE SUMMARY A 29-year-old man presented with progressive dyspnea for 1 mo.At the age of 10 years,he was diagnosed with panhypopituitarism associated with pituitary stalk interruption syndrome.Levothyroxine and hydrocortisone were given since then.To achieve ideal height,he received GH treatment for 5 years.The patient had an oxygen saturation of 78%and a partial pressure of arterial oxygen of 37 mmHg with an alveolar–arterial oxygen gradient of 70.2 mmHg.Abdominal ultrasonography showed liver cirrhosis and an enlarged spleen.Perfusion lung scan demonstrated intrapulmonary arteriovenous right-to-left shunt.HPS(very severe)was our primary consideration.His hormonal evaluation revealed GH deficiency and hypogonadotropic hypogonadism when thyroid hormone,cortisol,and desmopressin were administrated.After adding with long-acting recombinant human GH and testosterone for 14 mo,his liver function and hypoxemia were improved and his progressive liver fibrosis was stabilized.He was off the waiting list of liver transplantation.CONCLUSION Clinicians should screen HPS patients'anterior pituitary function as early as possible and treat them primarily with GH cocktail accordingly.

Cirrhosis and hepatopulmonary syndrome

Hepatopulmonary syndrome(HPS)is characterized as a triad:liver disease,intrapulmonary vascular dilatation and arterial hypoxemia.HPS is reported to be present in 4%to 32%of adult patients with end-stage liver disease and in 9%-20%of children.The pathogenesis of HPS has not been clearly identified.Portal hypertension causes impairment in the perfusion of the bowel and increases the enteral translocation of Gram(-)bacteria and endotoxins.This stimulates the release of vasoactive mediators,such as tumor necrosis factor-alpha,heme oxygenase-derived carbon monoxide and nitric oxide.Genetic alterations have not been associated with this syndrome yet;however,cytokines and chemokines have been suggested to play a role.Recently,it was reported that cumulated monocytes lead to the activation of vascular endothelial growth factor-dependent signaling pathways and pulmonary angiogenesis,which plays an important role in HPS pathogenesis.At present,the most effective and only radical treatment is a liver transplant(LT).Cirrhotic patients who are on the waiting list for an LT have a shorter survival period if they develop HPS.Therefore,it is suggested that all cirrhotic cases should be followed closely for HPS and they should have priority in the waiting list.

Reversion of severe hepatopulmonary syndrome in a non cirrhotic patient after corticosteroid treatment for granulomatous hepatitis:A case report and review of the literature

Hepatopulmonary syndrome （HPS） is defined as a clinical triad including liver disease, abnormal pulmonary gas exchange and evidence of intrapulmonary vascular dilatations. We report a 61-year-old male presented with fatigue, long-lasting fever, loss of weight, signs of portal hypertension, hepatosplenomegaly, cholestasis and progressive dyspnoea over the last year. Clinical, laboratory and histological findings confirmed the diagnosis of granulomatous hepatitis. HPS due to hepatic granulomainduced portal hypertension was proved to be the cause of severe hypoxemia of the patient as confirmed by contrast-enhanced echocardiography. Reversion of HPS after corticosteroid therapy was confirmed by a new contrastenhanced echocardiography along with the normalization of cholestatic enzymes and improvement of the patient＇ s conditions. This is the first case of complete reversion of HPS in a non-cirrhotic patient with hepatic granuloma, indicating that intrapulmonary shunt in liver diseases is a functional phenomenon and HPS can be developed even in miscellaneous liver involvement as in this case.

Hepatopulmonary syndrome: An update

Hepatopulmonary syndrome(HPS)is characterized by defects in oxygenation caused by intra-pulmonary vasodilation occurring because of chronic liver disease,portal hypertension,or congenital portosystemic shunts.Clinical implications of portal hypertension are very well-known,however,awareness of its effect on multiple organs such as the lungs are less known.The presence of HPS in chronic liver disease is associated with increased mortality.Medical therapies available for HPS have not been proven effective and definitive treatment for HPS is mainly liver transplantation(LT).LT improves mortality for patients with HPS drastically.This article provides a review on the definition,clinical presentation,diagnosis,and management of HPS.

Growth hormone ameliorates hepatopulmonary syndrome and nonalcoholic steatohepatitis secondary to hypopituitarism in a child:A case report

BACKGROUND Craniopharyngioma is a benign tumor that usually develops in children;however,it is located in the center and close to sensitive structures,such as the pituitary gland and hypothalamus.As the hypothalamus plays a crucial role in the homeostasis of anterior pituitary hormone synthesis,damage to the hypothalamus leads to multiple pituitary hormone deficiencies and non-alcoholic fatty liver disease,including hepatopulmonary syndrome(HPS).HPS has limited treatment and poor prognosis.CASE SUMMARY A girl aged 13 years and 6 mo underwent surgery for craniopharyngioma 6 years prior.Right craniotomy was performed with total resection via the corpus callosum approach,and the tumor at the base was approximately 3.5 cm×3.5 cm×4.0 cm.At 1 year postoperatively,she exhibited abdominal distension and weakness,and the laboratory tests revealed fatty liver disease.Thereafter,she had not visited the outpatient clinic for 2 years.Two years ago,she developed decreased activity endurance,severe cyanosis,chest tightness,wheezing,and intermittent and recurrent low fever after mild physical labor.Hepatobiliary ultrasonography,liver biopsy,and contrast echocardiography of the right heart showed cirrhosis and multiple pituitary hormone deficiencies,indicating HPS.After 1 year of treatment with recombinant human growth hormone,the liver function and oxygenation improved;she did not undergo liver transplantation.CONCLUSION Craniopharyngioma surgery can easily cause hypopituitarism,which can lead to nonalcoholic steatohepatitis and HPS in children.Early growth hormone therapy is important to improve the prognosis of these diseases.

Clinical Significance of a Myeloperoxidase Gene Polymorphism and Inducible Nitric Oxide Synthase Expression in Cirrhotic Patients with Hepatopulmonary Syndrome

The clinical significance of a myeloperoxidase (MPO) gene polymorphism and inducible nitric oxide synthase (iNOS) expression in cirrhotic patients with hepatopulmonary syndrome (HPS) was explored. Enrolled subjects were divided into three groups according to their disease/health conditions: the HPS group (cirrhotic patients with HPS; n=63), the non-HPS group (cirrhotic patients without HPS; n=182), and the control group (healthy subjects without liver disease; n=35). The distribution of the MPO–463 G/A genotype and its relationship with iNOS expression in a typical cell block from ascitic fluid were detected by immunohistochemistry and polymerase chain reaction-restricted fragment length polymorphism analysis (PCR-RFLP). In the HPS group, the partial pressure of oxygen in blood and ascitic fluid was significantly decreased (8.95±1.58 kPa and 6.81±0.95 kPa, respectively; both P<0.01), while the partial pressure of carbon dioxide significantly increased (4.62±0.20 kPa and 5.92±0.45 kPa, respectively; P<0.01). MPO and iNOS levels were significantly increased in the HPS group as compared with the non-HPS group. These increases were even more remarkable in ascitic fluid (41.36±11.62 and 13.23±4.81 μg/L; 10.27± 3.20 and 4.95±1.12 μg/L) than in blood (16.66±5.24 and 4.87±1.73 μg/L; 5.79±2.31 and 2.35±0.84 μg/L). The distribution of the MPO genotypes GG, GA, and AA were 76.2%, 22.2% and 1.6% in the HPS group, and 57.7%, 37.9% and 4.4% in the non-HPS group (P<0.05). The expression of iNOS was significantly higher in patients with the G alleles (G/G and G/A) (61.54%, 48/78) than in patients with A alleles (G/A and A/A) (38.46%, 30/78) (P<0.01). It was suggested that the expression levels of iNOS and MPO were correlated with HPS-induced hypoxemia. The MPO-463 G/A mutation might be a protective factor that prevents the development of HPS. The MPO might be involved in the regulation of iNOS expression. In humans, MPO pathways, the iNOS/NO system, and their interaction might have an impact on the occurrence and development of HPS.

Correlation between Pulmonary Endothelin Receptors and Alveolar-arterial Oxygen Gradient in Rats with Hepatopulmonary Syndrome

The correlation between pulmonary endothelin receptors and alveolar-arterial oxygen gradient （A aDO2） in rats with hepatopulmonary syndrome was investigated. Animals were divided into 2 groups： Sham operated （Sham） group and common bile duct ligation （CBDL） group. Arterial blood gas was evaluated by a blood gas analyzer. The concentrations of ET-1 in blood and lung tissue sample were evaluated by radioimmunoassay. The distribution and expression of two kinds of subtype receptor of ET-1, ETRA and ETRB were examined by in situ hybridization. The results showed that the level of A aDO2, was higher in CBDI. group than that in Sham group （P〈0.05）. The levels of plasma and pulmonary ET-1 in CBDL group were both higher than in Sham group （P〈0.05 ）. There was no significant difference in average A of ETRA between two groups by imaging analysis （0.21±0.06 vs 0.22±0.08, P〉0.05）, while that of ETRB was higher in CBDI. group than in Sham group （0.58±0.16 vs 0.28±0.07, P〈0.05）. The expression of ETRBinlung was positively correlated with A aDO2（P〈0.05）. It was concluded that the widened A-aDO2 may be related with enhancement of the expression of ETRB in lung.

Inhaled nitric oxide as a salvage therapy for refractory hypoxemia in the post-transplantation period of hepatopulmonary syndrome:An explorative report of three cases

Liver transplantation(LT)is the only effective treatment for hepatopulmonary syndrome(HPS).Moreover,perioperative refractory hypoxemia(pRH)is a prevalent life-threatening condition and has extremely limited treatment options.Here,we report three patients with HPS who experienced pRH after LT and were consecutively treated with different salvage therapies,ephedrine inhalation,intravenous use of methylene blue with nitric oxide(NO)inhalation,and NO inhalation alone.The results showed that unresolved severe hypoxia may induce fatal morbidity such as early biliary leakage and acute kidney injury.Early initiation of NO inhalation,rather than ephedrine,can significantly improve oxygenation in patients with pRH and may help prevent hypoxia-related complications.Therefore,based on the response to these exploratory salvage treatments,we further demonstrate the unique ventilation-perfusion mismatch pathophysiology in specific lung regions during pRH in HPS.We propose that early inhalation of NO is an important treatment option to rescue severe hypoxia in patients with HPS during the perioperative period of LT.

The Therapeutic Effects of Baicalein on the Hepatopulmonary Syndrome in the Rat Model of Chronic Common Bile Duct Ligation

Background and Aims:Hepatopulmonary syndrome(HPS)is characterized by arterial oxygenation defects due to pulmonary vascular dilation in liver disease.To date,liver transplantation remains the only effective treatment for HPS.This study aimed to explore the preventative role of baicalein in HPS development.Methods:Sixty male rats were randomly assigned to three groups:sham,common bile duct ligation(CBDL),and baicalein,receiving intraperitoneal injections of baicalein(40 mg·kg^(-1)·d^(-1),diluted in saline)for 21 days.Survival rate,liver and kidney function,and bile acid metabolism levels were evaluated.Liver and lung angiogenesis and hepatic glycogen staining were assessed,and the expression of relevant proteins was evaluated by immunohistochemistry.Results:Baicalein improved survival rates and hypoxemia in rats post-CBDL,reducing angiogenic protein levels and enhancing glucose homeostasis.Compared to the untreated group,baicalein suppressed the expression of vascular endothelial growth factor,placental growth factors,matrix metalloprotease 9 and C-X-C motif chemokine 2,and it increased the expression of glycemic regulatory proteins,including dipeptidyl peptidase-4,sirtuin 1,peroxisome proliferatoractivated receptor gamma co-activator 1α,and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3.Conclusion:Baicalein significantly improves hepatic function and hypoxia in HPS rats by attenuating pathological angiogenesis in the liver and lungs,showing promise as a treatment for HPS.