Hepatopulmonary syndrome

Natural history, risk factors, and outcome of hepatopulmonary syndrome in pediatric liver diseases

BACKGROUND

Limited pediatric literature is available regarding hepatopulmonary syndrome (HPS) especially in subjects with biliary atresia (BA) despite its proven prognostic significance. Thus, we aimed to study the natural history, risk factors, and outcome of HPS in BA and other chronic liver disease (CLD) subjects.

METHODS

All children (BA and other non-BA CLDs) older than 6 months of age were included in the study. HPS was diagnosed on the basis of standard international criteria. Also, fractional exhaled nitric oxide (FeNO) was measured at baseline.

RESULTS

During the study period from January 2017 to December 2018, there were 42 children in BA and 62 in the CLD group. The overall prevalence of HPS was 42.3%: 57.1% in the BA group and 32.2% in the CLD group. Median age at HPS diagnosis was 14.4 months and 90 months in the BA and non-BA CLD groups, respectively. By the end of study period, the prevalence of HPS in the BA group further increased to 73.8% at 0.7% per month. Lower serum albumin (p < 0.05) in BA and higher splenic Z scores (p 0.013) in other CLDs were found to be significant risk factors for HPS. FeNO measurement did not reach diagnostic significance.

CONCLUSION

Prevalence of HPS is higher and also develops at an earlier age in the BA group compared to other CLDs. Also, risk of HPS development increases with increasing disease duration in BA. Lower serum albumin in BA and higher splenic Z scores in other CLDs may predict risk for HPS development.

Hepatopulmonary Syndrome in children: a comparative study of non-cirrhotic vs. cirrhotic portal hypertension

BACKGROUND & AIMS

Hepatopulmonary syndrome in children has not been extensively studied particularly in different subsets of portal hypertension. We prospectively studied hepatopulmonary syndrome in children with cirrhosis and extrahepatic portal venous obstruction. Their comparison might shed light on the pathogenesis of hepatopulmonary syndrome.

METHODS

Between 1 to 18 years of age, 135 children with portal hypertension (cirrhosis 35, extrahepatic portal venous obstruction 100) were studied. Hepatopulmonary syndrome was diagnosed by the presence intrapulmonary shunt using transthoracic contrast echocardiography and hypoxia/orthodeoxia (in arterial blood gas examination). Comparative analyses were done for both the groups, and also intra- and intergroups with and without hepatopulmonary syndrome.

RESULT

Of 135 children, hepatopulmonary syndrome occurred more frequently in cirrhosis (40%) than extrahepatic portal venous obstruction (13%) (P = 0.01). Cirrhotics with hepatopulmonary syndrome were symptomatic (85% vs. 14%, P < 0.001) and had longer disease duration [16(1-120) months vs. 28 (1-168) months, P = 0.01] as compared to cirrhotics without hepatopulmonary syndrome. Prevalence of hepatopulmonary syndrome among cirrhotics did not correlate with the severity of liver disease as assessed by both paediatric end-stage liver disease score and Child-Turcotte-Pugh score. Patients with extrahepatic portal venous obstruction and hepatopulmonary syndrome remain asymptomatic manifesting with clubbing alone (38%).

CONCLUSIONS

Hepatopulmonary syndrome occurs more frequently in cirrhosis, a majority being symptomatic with more severity in comparison to extrahepatic portal venous obstruction having no symptoms and less severity. There seems to be a role of liver dysfunction besides portal hypertension as an added factor in the pathogenesis of hepatopulmonary syndrome.

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’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.

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.

TNF-α neutralization improves experimental hepatopulmonary syndrome in rats

BACKGROUND/AIM

TNF-α is increased in hepatopulmonary syndrome (HPS). Pentoxifylline (PTX) mitigated experimental HPS through the inhibition of TNF-α. However, PTX has pleiotropic effects besides the inhibition of TNF-α. This study is to neutralize TNF-α with specific monoclonal antibody to TNF-α (TNF-α McAb) to investigate the effect of TNF-α on HPS.

MATERIALS AND METHODS

Hepatopulmonary syndrome was induced by common bile duct ligation (CBDL); controls were sham operated. The endpoints were 1, 2, 3, 4 and 5 weeks after surgery. (99m) Technetium-macroaggregated albumin (Tc-MAA) was to evaluate intrapulmonary arteriovenous shunts; Portal venous pressure, cardiac output and mean blood pressure (MAP) were also measured. Serum was for Alanine transaminase (ALT), endotoxin, TNF-α and nitric oxide (NO) measurements, liver for histology, lung for histology and iNOS, PI3K/Akt expression assay.

RESULTS

Portal vein pressure was significantly elevated and MAP decreased in CBDL rats. Tc-MAA was mainly located in lung and very weak in brain in sham group and mainly in brain of CBDL rats. TNF-α McAb significantly decreased the radioactivity in the brain, reduced cardiac output, increased MAP and systemic vascular resistance (SVR) in CBDL animals. Serum ALT, endotoxin, TNF-α and NO were significantly increased. TNF-α McAb significantly decreased these serum indices in CBDL rats. TNF-α McAb significantly alleviated liver damage, decreased alveolar-arterial gradient and inhibited iNOS, PI3K/Akt and p-Akt expression in lung tissue. Furthermore, TNF-α McAb significantly attenuated the inflammatory response in lung.

CONCLUSION

TNF-α McAb improves HPS in cirrhotic rats; this effect is likely mediated through the inhibition of TNF-α PI3K/Akt-NO pathway.

Lung diffusion capacity in early cirrhosis: is lung diffusion capacity a predictor of esophageal varices and ascites?

BACKGROUND

Varices and ascites are clinical manifestations of hyperdynamic circulation syndrome originating from increased nitric oxide in cirrhosis. Research was conducted in order to find any correlation between lung diffusion capacity and the presence of varices and ascites in cirrhosis.

METHODS

The study was conducted on a total of 120 subjects. Tests for pulmonary function, including carbon monoxide diffusing capacity (DLCO) and fractional exhaled nitric oxide (FENO), were performed.

RESULTS

DLCO/alveolar ventilation (VA) values were lower in cirrhosis and chronic liver disease groups than in the control group (3.79 vs. 4.5 vs. 5.1 ml/mmHg/min, p<0.001). DLCO/VA showed a negative correlation with the Child score and the MELD score (r=-0.3 vs. r=-0.41). In patients with varices, the DLCO/VA value was 3.75 ml/mmHg/min, which was lower than the 4.12 ml/mmHg/min observed in patients without varices (p=0.029). FENO levels were higher in the chronic liver disease and liver cirrhosis groups than in the control group. FENO and DLCO showed a negative correlation (r=-0.25, p=0.006). The frequency of significant varix and decompensation were higher in the high FeNO group.

CONCLUSIONS

Lung diffusion capacity decreased according to the disease's severity in early cirrhosis, and showed a good correlation with esophageal varices and ascites.

Pulmonary artery embolotherapy in a patient with type I hepatopulmonary syndrome after liver transplantation

Although liver transplantation (LT) is the only effective treatment option for hepatopulmonary syndrome (HPS), the post-LT morbidity and mortality have been high for patients with severe HPS. We performed post-LT embolotherapy in a 10-year-old boy who had severe type I HPS preoperatively, but he failed to recover early from his hypoxemic symptoms after an LT. Multiple embolizations were then successfully performed on the major branches that formed the abnormal vascular structures. After the embolotherapy, the patient had symptomatic improvement and he was discharged without complications.

Hypertrophic osteoarthropathy in the hepatopulmonary syndrome

Hypertrophic osteoarthropathy is an uncommon disease in the pediatric age group characterized by noninflammatory joint effusions, terminal digit clubbing, and radiographic evidence of periosteal new bone formation affecting the hands, feet, and distal limbs. The hepatopulmonary syndrome is also uncommon in childhood and presents as hepatic dysfunction, impaired arterial oxygenation, and intrapulmonary shunting. We report the case of a 17-year-old male with a history of liver transplantation at 4 months for biliary atresia who was initially diagnosed with juvenile rheumatoid arthritis but later developed features of classic hypertrophic osteoarthropathy. In addition, he was found to have the hepatopulmonary syndrome. It is important to consider hypertrophic osteoarthropathy as an imitator of juvenile rheumatoid arthritis, to recognize its known association with chronic liver disease, and to know that hepatopulmonary syndrome can occur in the setting of hypertrophic osteoarthropathy.

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.

Hepatopulmonary syndrome, an unusual cause of hypoxemia

A six-year-old boy presented with cough, cyanosis and clubbing. Investigations revealed hypoxia (PaO2 53 mm Hg on room air) which was only partially correctable (PaO2 73 mm Hg) with 100% oxygen administered through a non re breathing face mask. Liver function tests showed elevated total bilirubin, and transaminases, liver biopsy confirmed chronic hepatitis and endoscopy showed grade three varices. A contrast enhanced echocardiography (bubble study) revealed pulmonary arterio-venous communication. A diagnosis of hepatopulmonary syndrome was made based on the triad of hypoxemia, liver disease and intra pulmonary vascular communications.