The hepatopulmonary syndrome

Pulmonary complications of hepatic diseases

Severe chronic liver disease (CLD) may result from portal hypertension, hepatocellular failure or the combination of both. Some of these patients may develop pulmonary complications independent from any pulmonary pathology that they may have. Among them the hepatopulmonary syndrome (HPS), portopulmonary hypertension (PPH) and hepatic hydrothorax (HH) are described in detail in this literature review. HPS is encountered in approximately 15% to 30% of the patients and its presence is associated with increase in mortality and also requires liver transplantation in many cases. PPH has been reported among 4%-8% of the patient with CLD who have undergone liver transplantation. The HH is another entity, which has the prevalence rate of 5% to 6% and is associated in the absence of cardiopulmonary disease. These clinical syndromes occur in similar pathophysiologic environments. Most treatment modalities work as temporizing measures. The ultimate treatment of choice is liver transplant. This clinical review provides basic concepts; pathophysiology and clinical presentation that will allow the clinician to better understand these potentially life-threatening complications. This article will review up-to-date information on the pathophysiology, clinical features and the treatment of the pulmonary complications among liver disease patients.

Intrapulmonary vascular dilatation evaluated by 99mTc-MAA scintigraphy and its association with portal hypertension in schistosomiasis

Background

Portal hypertension is responsible for various complications in patients with schistosomiasis, among them intrapulmonary vascular dilations (IPVD). In cirrhotic patients the presence of IPVD is a sign of poor prognosis, but in patients with hepatosplenic schistosomiasis (HSS) there are no studies assessing the significance of this change. The aim of this study was to evaluate the occurrence of IPVD through ^99mTc-MAA scintigraphy in patients with HSS and its relationship with clinical, laboratory, endoscopic and ultrasound parameters.

Methods

Cross-sectional study evaluating 51 patients with HSS. Patients were diagnosed with IPVD when the brain uptake of ^99mTc-MAA was higher than 6%. Subsequently, they were divided according to presence (G1) or absence (G2) of IPVD and variables were compared between groups.

Results

Overall, 51 patients with mean age of 56±12 years were assessed. IPVD was observed in 31 patients (60%). There was no statistically significant differences between groups when clinical, laboratory and endoscopic parameters were compared. Regarding ultrasound parameters, the splenic vein diameter was smaller in G1 (0.9±0.3 cm) compared to G2 (1.2±0.4 cm), p = 0.029.

Conclusion

In patients with HSS, the occurrence of IPVD by ^99mTc-MAA scintigraphy was high and was associated with lower splenic vein diameter, which can be a mechanism of vascular protection against portal hypertension. However, more studies are needed to determine the clinical significance of the early diagnosis and natural evolution of IPVD in this population.

Intrapulmonary vascular dilatation (IPVD) is the key event in development of hepatopulmonary syndrome, an arterial oxygenation defect in patients with portal hypertension. IPVD diagnosis can be made by EchoDopplercardiography or ^99mTc-macroaggregated albumin scintigraphy (^99mTc-MAA), and ethiopatogeny is still unknown. In Northeastern Brazil, hepatosplenic schistossomiasis (HSS) is the main cause of portal hypertension. In cirrhotics, the presence of IPVD influences survival and candidacy for liver transplantation, however, in HSS patients, IPVD has been poorly studied, specially using lung perfusion scan with ^99mTc-MAA. Some authors believe that IPVD is common in HSS and in the existence of differences in indirect portal hypertension parameters between patients with and without IPVD. All patients were distributed into two groups according to presence or not of IPVD, and laboratorial, endoscopy and ultrasound tests were perfomed. Occurrence of IPVD was high and was associated with lower splenic vein diameter, which can be a vascular protection mechanism against portal hypertension status.

(99m)Technetium-macroaggregated albumin perfusion lung scan versus contrast enhanced echocardiography in the diagnosis of the hepatopulmonary syndrome in children with chronic liver disease

BACKGROUND AND AIMS

The hepatopulmonary syndrome (HPS) is a triad of advanced chronic liver disease (CLD), arterial hypoxemia and intrapulmonary arteriovenous shunting in the absence of a primary cardiopulmonary disease. HPS has been more frequently reported in adults than in children with no data on its prevalence in children with CLD. The aim of this study was to detect the prevalence of the HPS in a cohort of children with CLD because of chronic hepatitis B and/or C virus infection, schistosomiasis as well as inborn metabolic errors. We also aimed to evaluate the role of Technetium labeled macroaggregated albumin (Tc--MAA) perfusion lung scan versus contrast enhanced echocardiography (CEE) with intravenous injection of agitated saline in the diagnosis and quantification of intrapulmonary shunts and their relationship to important clinical and laboratory findings.

METHODS

Forty Egyptian children (22 males) were investigated. Their ages ranged from 5 to 12 years (with a mean of 9.5 years). Twenty individuals proved to have cirrhosis.

RESULTS

Blood gas determination revealed more significant arterial hypoxemia in cirrhotics than noncirrhotics both under room air and after breathing 100% oxygen for 15 mins. CEE showed comparable cardiac measurements in cirrhotic and noncirrhotic patients, and diagnosed intrapulmonary shunts in three hypoxemic cirrhotic patients; whereas Tc--MAAperfusion lung scan diagnosed shunts in seven patients (five of them cirrhotic). The presence of shunts was significantly correlated with the duration of CLD, clinical findings, presence of cirrhosis and porto-systemic collaterals. We calculated for each patient a shunt index (SI) by the formula: (activity outside thorax/activity outside plus inside thorax) 100; and an SI value of 0.278 was found to be a cutoff value for shunt detection. All patients with SI above this value had shunting associated with hypoxemia and all patients with SI below this value had no hypoxemia (specificity 100%).

CONCLUSION

Arterial hypoxemia and intrapulmonary shunts were diagnosed in 17.5% of this cohort of children with cirrhotic or noncirrhotic CLD representing the classic HPS. Tc--MAA perfusion lung scan was more sensitive than CEE in detection of intrapulmonary shunts. SI cutoff value of 0.278 was found to be highly specific for shunt detection and we recommend its validation in further studies.

N-acetylcysteine effects on genotoxic and oxidative stress parameters in cirrhotic rats with hepatopulmonary syndrome

The aim of this study was to evaluate the potential antioxidant effects of N-acetylcysteine in hepatopulmonary syndrome, a complication of cirrhosis, using an experimental model of common bile duct ligation in rats. Male Wistar rats were divided into four experimental groups: CBDL (animals submitted to common bile duct ligation); Sham (animals submitted to simulated common bile duct ligation); Sham + N-acetylcysteine, and CBDL + N-acetylcysteine. N-acetylcysteine (10 mg/kg, intraperitoneally) was administered for 2 weeks starting on day 14 after surgery. Some alterations in the liver integrity were investigated by evaluation of serum enzymes aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and arterial blood gases. Lipoperoxidation by thiobarbituric acid-reactive substances assay, superoxide dismutase activity and total nitrates was measured as parameters of oxidative stress, performed on lung homogenates. Micronucleus assay in bone marrow and comet assay in lung, liver and blood were performed to assess the genotoxic effects by oxidative stress. The results showed an improvement in the enzymatic parameters and arterial blood gases, a reduction of lipoperoxidation and in the total nitrates after treatment with N-acetylcysteine. Histological analysis showed vasodilatation in the lung, which was reversed by N-acetylcysteine. Micronuclei frequency and DNA damage in lung and liver were increased in the CBDL group. N-Acetylcysteine caused no genotoxic effect and did not influence the induction of micronucleus in bone marrow and DNA damage in lung and liver. The results suggest protective effects after treatment with N-acetylcysteine in cirrhotic rats with hepatopulmonary syndrome.

Platypnea-orthodeoxia: Report of Two Cases and Review of the Literature

We describe two unusual cases of platypnea. The first patient had chronic obstructive pulmonary disease, but platypnea did not respond to chronic obstructive pulmonary disease therapy. He was found to have multiple pulmonary emboli, and symptoms rapidly improved on anticoagulation therapy. The second patient had Parkinson disease and developed severe platypnea, an association that has not been previously described. She had significant postural hypotension and responded to therapy with fludrocortisone.