Analysis of intrapulmonary right to left shunt in the hepatopulmonary syndrome

Lung Function in Women With and Without Human Immunodeficiency Virus

BACKGROUND

Prior studies have found that human immunodeficiency virus (HIV) infection is associated with impaired lung function and increased risk of chronic lung disease, but few have included large numbers of women. In this study, we investigate whether HIV infection is associated with differences in lung function in women.

METHODS

This was a cross-sectional analysis of participants in the Women's Interagency HIV Study, a racially and ethnically diverse multicenter cohort of women with and without HIV. In 2018-2019, participants at 9 clinical sites were invited to perform spirometry. Single-breath diffusing capacity for carbon monoxide (DLCO) was also measured at selected sites. The primary outcomes were the post-bronchodilator forced expiratory volume in 1 second (FEV1) and DLCO. Multivariable regression modeling was used to analyze the association of HIV infection and lung function outcomes after adjustment for confounding exposures.

RESULTS

FEV1 measurements from 1489 women (1062 with HIV, 427 without HIV) and DLCO measurements from 671 women (463 with HIV, 208 without HIV) met standards for quality and reproducibility. There was no significant difference in FEV1 between women with and without HIV. Women with HIV had lower DLCO measurements (adjusted difference, -0.73 mL/min/mm Hg; 95% confidence interval, -1.33 to -.14). Among women with HIV, lower nadir CD4 + cell counts and hepatitis C virus infection were associated with lower DLCO measurements.

CONCLUSIONS

HIV was associated with impaired respiratory gas exchange in women. Among women with HIV, lower nadir CD4 + cell counts and hepatitis C infection were associated with decreased respiratory gas exchange.

Supine vs upright exercise in patients with hepatopulmonary syndrome and orthodeoxia: study protocol for a randomized controlled crossover trial

BACKGROUND

The hepatopulmonary syndrome (HPS) is a pulmonary complication of liver disease found in 10 to 32% of patients with cirrhosis and is characterized by intrapulmonary vascular dilatations and abnormal oxygenation. Liver transplantation is the only effective therapy for this disease. Patients with HPS have significant exercise limitations, impacting their quality of life and associated with poor liver transplant outcomes. Many patients with HPS exhibit orthodeoxia-an improvement in oxygenation in the supine compared to the upright position. We hypothesize that exercise capacity will be superior in the supine compared to the upright position in such patients.

METHODS

We propose a randomized controlled crossover trial in patients with moderate HPS (PaO₂ < 80 mmHg) and orthodeoxia (supine to upright PaO₂ decrease > 4 mmHg) comparing the effect of supine vs upright position on exercise. Patients with pulmonary hypertension, FEV1/FVC ratio < 0.65, significant coronary artery disease, disorders preventing or contraindicating use of a cycle ergometer, and/or moderate or severe ascites will be excluded. Participants will be randomized to cycle ergometry in either the supine or upright position. After a short washout period (a minimum of 1 day to a maximum of 4 weeks), participants will crossover and perform an exercise in the alternate position. Exercise will be performed at a constant work rate of 70-85% of the predicted peak work rate until the "stopping time" is reached, defined by exhaustion, profound desaturation, or safety concerns (drop in systolic blood pressure or life-threatening arrhythmia). The primary outcome will be the difference in the stopping time between exercise positions, compared with a repeated measures analysis of variance method with a mixed effects model approach. The model will be adjusted for period effects. P < 0.05 will be considered statistically significant.

DISCUSSION

HPS patients have hypoxemia leading to significant exercise limitations. If our study is positive, a supine exercise regimen could become a routine prescription for patients with HPS and orthodeoxia, enabling them to exercise more effectively. Future studies could explore the corresponding effects of a supine exercise training regimen on physiologic variables such as long-term exercise capacity, quality of life, dyspnea, and liver transplantation outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov Protocol Registration and Results System (PRS) NCT04004104 . Registered on 1 July 2019.

Non-invasive assessment of intrapulmonary shunt and ventilation to perfusion ratio in children with hepatopulmonary syndrome before and after liver transplantation

OBJECTIVES

To use the oxyhaemoglobin dissociation curve (ODC) to non-invasively measure the ventilation perfusion ratio (V_A/Q) and right-to-left intrapulmonary vascular shunt before and after liver transplantation (LT) in children with hepatopulmonary syndrome (HPS). To investigate whether the right-to-left shunt derived by ODC correlated with the shunt derived by technetium-99 labelled macroaggregated albumin lung perfusion scan (MAA).

METHODS

A retrospective cohort study at King's College Hospital NHS Foundation Trust, London, UK was performed between 1998 and 2016. The V_A/Q and right-to-left shunt were non-invasively measured pre and post LT. The pre-LT right-to-left intrapulmonary shunt was also measured by MAA. The non-invasively derived pre-LT shunt was correlated with the shunt derived by MAA.

RESULTS

Fifteen children with HPS were studied with a median (IQR) age at LT of 8.8 (6.6-12.9) years. The median (IQR) pre-LT V_A/Q [0.49 (0.42-0.65)] was lower compared to the post-LT V_A/Q [0.61 (IQR 0.54-0.72), p = 0.012]. The median (IQR) pre-LT shunt was 19 (3-24) % which decreased to zero in all but one children post-LT, (p = 0.001). The MAA-derived shunt was significantly positively correlated with the ODC-derived shunt (r = 0.783, p = 0.001). The mean (SD) difference between shunt derived by ODC and shunt derived by MAA was 0.5 (7.2) %.

CONCLUSIONS

Ventilation/perfusion impairment reverses but not completely resolves after liver transplantation in children with hepatopulmonary syndrome. The non-invasive method for estimating intrapulmonary shunting could be used as an alternative to the macroaggregated albumin scan in this population.

The utility of the macro-aggregated albumin lung perfusion scan in the diagnosis and prognosis of hepatopulmonary syndrome in cirrhotic patients candidates for liver transplantation

BACKGROUND

The macro-aggregated albumin lung perfusion scan (99mTc-MAA) is a diagnostic method for hepatopulmonary syndrome (HPS).

GOAL

To determine the sensitivity of 99mTc-MAA in diagnosing HPS, to establish the utility of 99mTc-MAA in determining the influence of HPS on hypoxemia in patients with concomitant pulmonary disease and to determine the correlation between 99mTc-MAA values and other respiratory parameters.

METHODS

Data from 115 cirrhotic patients who were eligible for liver transplantation (LT) were prospectively analyzed. A transthoracic contrast echocardiography and 99mTc-MAA were performed in 85 patients, and 74 patients were diagnosed with HPS.

RESULTS

The overall sensitivity of 99mTc-MAA for the diagnosis of HPS was 18.9% (14/74) in all of the HPS cases and 66.7% (4/6) in the severe to very severe cases. In HPS patients who did not have lung disease, the degree of brain uptake of 99mTc-MAA was correlated with the alveolar-arterial oxygen gradient (A-a PO2) (r = 0.32, p < 0.05) and estimated oxygen shunt (r = 0.41, p < 0.05) and inversely correlated with partial pressure of arterial oxygen (PaO2) while breathing 100% O2 (r = -0.43, p < 0.05). The 99mTc-MAA was positive in 20.6% (7/36) of the patients with HPS and lung disease. The brain uptake of 99mTc-MAA was not associated with mortality and normalized in all cases six months after LT.

CONCLUSIONS

The 99mTc-MAA is a low sensitivity test for the diagnosis of HPS that can be useful in patients who have concomitant lung disease and in severe to very severe cases of HPS. It was not related to mortality, and brain uptake normalized after LT.

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.

Defining and characterizing severe hypoxemia after liver transplantation in hepatopulmonary syndrome

Hepatopulmonary syndrome is defined as a triad of liver disease, intrapulmonary vascular dilatations, and abnormal gas exchange, and it carries a poor prognosis. Liver transplantation is the only known cure for this syndrome. Severe hypoxemia in the early postoperative period has been reported to be a major complication and often leads to death in this population, but it has been poorly characterized. We sought to propose an objective definition for this complication and to describe its risk factors, incidence, and outcomes. We performed a systematic literature search and reviewed our single-center experience to characterize this complication. On the basis of the most commonly applied definition in 27 identified studies, we objectively defined severe postoperative hypoxemia as hypoxemia requiring a 100% fraction of inhaled oxygen to maintain a saturation ≥ 85% and out of proportion to any concurrent lung process. Nineteen of the 27 reports (70%) fulfilled this definition, as did 4 of the 21 patients (19%) at our center. We determined the prevalence and mortality of this complication from reports including 10 or more consecutive patients and providing sufficient postoperative details to determine whether this complication had occurred. In these reports, the prevalence of this complication was 12% (25/209). For the 11 cases with reported outcomes, the posttransplant mortality rate was 45% (5/11). There was a trend toward an increased risk of developing this complication in patients with very severe preoperative hypoxemia, defined as a partial pressure of arterial oxygen ≤ 50 mm Hg (8/41 with very severe hypoxemia versus 3/49 without severe hypoxemia, P = 0.053), and there was a significantly increased risk for patients with anatomic shunting ≥ 20% (7/25 with anatomic shunting ≥ 20% versus 1/25 without anatomic shunting ≥ 20%, P = 0.049). In conclusion, increased preoperative vigilance for this common complication is required among high-risk patients, and further research is required to identify the best management strategies.

Pulmonary vascular diseases

Diseases of the pulmonary vasculature are a cause of increased pulmonary vascular resistance (PVR) in pulmonary embolism, chronic thromboembolic pulmonary hypertension (CTEPH), and pulmonary arterial hypertension or decreased PVR in pulmonary arteriovenous malformations on hereditary hemorrhagic telangiectasia, portal hypertension, or cavopulmonary anastomosis. All these conditions are associated with a decrease in both arterial PO2 and PCO2. Gas exchange in pulmonary vascular diseases with increased PVR is characterized by a shift of ventilation and perfusion to high ventilation-perfusion ratios, a mild to moderate increase in perfusion to low ventilation-perfusion ratios, and an increased physiologic dead space. Hypoxemia in these patients is essentially explained by altered ventilation-perfusion matching amplified by a decreased mixed venous PO2 caused by a low cardiac output. Hypocapnia is accounted for by hyperventilation, which is essentially related to an increased chemosensitivity. A cardiac shunt on a patent foramen ovale may be a cause of severe hypoxemia in a proportion of patients with pulmonary hypertension and an increase in right atrial pressure. Gas exchange in pulmonary arteriovenous malformations is characterized by variable degree of pulmonary shunting and/or diffusion-perfusion imbalance. Hypocapnia is caused by an increased ventilation in relation to an increased pulmonary blood flow with direct peripheral chemoreceptor stimulation by shunted mixed venous blood flow.

Examination of the carbon monoxide diffusing capacity (DL(CO)) in relation to its KCO and VA components

The single-breath carbon monoxide diffusing capacity (DL(CO)) is the product of two measurements during breath holding at full inflation: (1) the rate constant for carbon monoxide uptake from alveolar gas (kco [minute(-1)]) and (2) the "accessible" alveolar volume (Va). kco expressed per mm Hg alveolar dry gas pressure (Pb*) as kco/Pb*, and then multiplied by Va, equals Dl(CO); thus, Dl(CO) divided by Va (DL(CO)/Va, also called Kco) is only kco/Pb* in different units, remaining, essentially, a rate constant. The notion that DL(CO)/Va "corrects" DL(CO) for reduced Va is physiologically incorrect, because DL(CO)/Va is not constant as Va changes; thus, the term Kco reflects the physiology more appropriately. Crucially, the same DL(CO) may occur with various combinations of Kco and Va, each suggesting different pathologies. Decreased Kco occurs in alveolar-capillary damage, microvascular pathology, or anemia. Increased Kco occurs with (1) failure to expand normal lungs to predicted full inflation (extrapulmonary restriction); or (2) increased capillary volume and flow, either globally (left-to-right intracardiac shunting) or from flow and volume diversion from lost or damaged units to surviving normal units (e.g., pneumonectomy). Decreased Va occurs in (1) reduced alveolar expansion, (2) alveolar damage or loss, or (3) maldistribution of inspired gases with airflow obstruction. Kco will be greater than 120% predicted in case 1, 100-120% in case 2, and 40-120% in case 3, depending on pathology. Kco and Va values should be available to clinicians, as fundamental to understanding the clinical implications of DL(CO). The diffusing capacity for nitric oxide (DL(NO)), and the DL(NO)/DL(CO) ratio, provide additional insights.

Pulmonary vascular complications of chronic liver disease: Pathophysiology, imaging, and treatment

To review the pathogenesis of pulmonary vascular complications of liver disease, we discuss their clinical implications, and therapeutic considerations, with emphasis on potential reversibility of the hepatopulmonary syndrome after liver transplantation. In this review, we also discuss the role of imaging in pulmonary vascular complications associated with liver disease.

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.

Impact of hepatopulmonary syndrome on quality of life and survival in liver transplant candidates

BACKGROUND & AIMS

Hepatopulmonary syndrome (HPS) affects 10%-30% of patients with cirrhosis and portal hypertension, but the impact on functional status, quality of life, and survival is poorly defined. We assessed the impact of HPS in patients evaluated for liver transplantation.

METHODS

We performed a prospective multicenter cohort study of patients being evaluated for liver transplantation in 7 academic centers in the United States. Patients with HPS (defined as an increased alveolar-arterial oxygen gradient with intrapulmonary vasodilation) were compared with those without HPS in terms of demographics and clinical variables. New York Heart Association functional class, quality of life, and survival were assessed.

RESULTS

Seventy-two patients with HPS and 146 patients without HPS were compared. There were no differences in age, sex, or etiology or severity of liver disease between the groups; however, patients with HPS were less likely to have a history of smoking (P = .03). Patients with HPS had worse New York Heart Association functional class (P = .005) and had significantly worse quality of life in certain domains compared with patients without HPS. In addition, patients with HPS also had a significantly increased risk of death compared with patients without HPS despite adjustment for age, sex, race/ethnicity, Model for End-Stage Liver Disease score, and liver transplantation (adjusted hazard ratio = 2.41; 95% confidence interval, 1.31-4.41; P = .005).

CONCLUSIONS

HPS was associated with a significant increase in risk of death as well as worse functional status and quality of life in patients evaluated for liver transplantation.

Mcp-1, eNOS, tPA and PAI-1 gene polymorphism and correlation of genotypes and phenotypes in hepatopulmonary syndrome

AIM

The aim of this case-control study was to investigate both the distribution of MCP-1, eNOS, tPA and PAI-1 gene polymorphism and correlation of genotypes and phenotypes.

METHOD

Between September 1997-January 2005, 20 patients with HPS (group 1) were compared with a group of cirrhotic patients (group 2, n = 19) as well as unrelated healthy controls (group 3, n = 59) in respect to MCP1, eNOS, tPA and PAI-1 gene polymorphism frequency distribution.

RESULTS

MCP1-2518G allele carriage in patients with HPS was higher than in controls (P = 0.01). In non-HPS cirrhotic patients, eNOS Glu298Asp, Asp gene carriers and frequency of Asp alleles were detected to be considerably higher than in patients with HPS and healthy controls (P < 0.05).

CONCLUSION

HPS is more common in patients with MCP-1 2518G gene carriage; conversely it is less frequent in patients with high frequency of eNOS 298Asp allele and eNOS 298Asp carriage.

Childhood cirrhosis, hepatopulmonary syndrome and liver transplantation

OBJECTIVES

The hepatopulmonary syndrome (HPS) is characterized as a triad: liver disease, intrapulmonary vascular dilatation, and arterial hypoxemia. The aim of this study is to analyze outcome of children with HPS in liver transplant era.

METHODS

Between September 1996 and November 2006, 172 cirrhotic patients (median age 5 years; range 0.2-22 years, M/F; 97/75) were followed at Ege University Pediatric Gastroenterology, Hepatology and Nutrition Unit. All patients were evaluated by chest radiography, arterial blood gas analysis, and alveolar-arterial oxygen tension difference, contrast echocardiography (CEE) after and before the liver transplantation.

RESULTS

HPS was diagnosed in 33 patients (19%) by CEE. None of them had pulmonary hypertension. HPS was not found related to etiology of the liver disease. Portal hypertension was found related to the development of HPS (75.7% in patients with HPS and 54.6% in others, p = 0.02). 17 of 33 patients with HPS underwent liver transplantation. Preoperative and postoperative period of these patients was uneventful. Patients were extubated in the operating room except for two. Median follow up of transplanted children was 1.9 year (range; 0.75-10 years). Arterial blood gas analysis and CEE positivity regressed in all of them by postoperative 6th month.

CONCLUSIONS

HPS is a serious and important complication of cirrhotic children that leads to tissue hypoxia and central cyanosis. HPS seems reversible after liver transplantation in all patients.

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.

Left atrial volume: a novel predictor of hepatopulmonary syndrome

OBJECTIVES

We studied patients with hepato-pulmonary syndrome (HPS). We found that HPS is frequently present in patients with left atrial enlargement. The aim of this prospective study was to evaluate the possible correlation between left atrial volume and HPS.

METHODS

Adult patients (>18 yr old) with biopsy proven liver cirrhosis who were referred for liver transplantation were enrolled in the study. Diagnosis of HPS was established when the following points were fulfilled: (a) the presence of chronic liver disease, (b) increased alveolar-arterial difference (AaDO(2)), (c) intrapulmonary vascular dilatation, and (d) absence of primary cardiac or pulmonary disease.

RESULTS

We enrolled 41 patients (mean age 47.1 +/- 10.6 yr) diagnosed with HPS. Also 108 Child-Pugh score matched cirrhotic patients (mean age 49.2 +/- 9.3 yr) who have negative contrast echocardiography and normal age-related AaDO(2) were selected as a control group for the purpose of comparison of left atrial volume (LAV). LAV was significantly greater in patients with HPS compared to the control group (55.1 +/- 7.5 mL vs 37.1 +/- 9.3 mL, P < 0.05). The area under the receiver-operating characteristic (ROC) curve for LAV was 0.903 (Cut point >/= 50 mL, sensitivity 86.3%, specificity 81.2%).

CONCLUSION

In the context of liver cirrhosis, LAV >/= 50 mL is a simple and feasible parameter to detect HPS.

Utility of pulse oximetry screening for hepatopulmonary syndrome

BACKGROUND & AIMS

Hepatopulmonary syndrome is characterized by oxygenation abnormalities caused by intrapulmonary vasodilatation in the setting of liver disease and/or portal hypertension. This syndrome occurs in approximately 15%-30% of cirrhotic patients and influences mortality and transplant candidacy. However, no specific screening guidelines are established. We evaluated pulse oximetry with contrast echocardiography in detecting hepatopulmonary syndrome in a cohort of patients undergoing evaluation for liver transplantation.

METHODS

One hundred twenty-seven consecutive patients referred for liver transplantation evaluation were prospectively enrolled and underwent pulse oximetry, contrast echocardiography, and arterial blood gas measurements on room air. Demographic, clinical, and laboratory data were recorded and analyzed.

RESULTS

Forty-one (32%) patients were found to have hepatopulmonary syndrome. There were no significant differences in demographic or clinical features compared with patients without hepatopulmonary syndrome, with the exception of pulse oximetry and oxygenation abnormalities. With a threshold value of <96%, pulse oximetry had a sensitivity and specificity of 100% and 88%, respectively, for detecting patients with a partial pressure of oxygen <60 mm Hg. Receiver operator characteristic analysis revealed that a pulse oximetry value of < or =94% detected all patients with a partial pressure of oxygen <60 mm Hg with an increased specificity of 93%. In addition, higher pulse oximetry thresholds reliably identified HPS patients with less severe hypoxemia, albeit with lower specificity.

CONCLUSIONS

Pulse oximetry is a simple, low cost, and widely available technique that reliably predicts the presence and severity of hypoxemia in patients with hepatopulmonary syndrome. Institution of pulse oximetry screening might enhance detection and improve management of hepatopulmonary syndrome in cirrhosis.

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

The hepatopulmonary syndrome (HPS) is present in 15-20% of patients with cirrhosis undergoing orthotopic liver transplantation (OLT) evaluation. Both preoperative and post-OLT mortality is increased in HPS patients particularly when hypoxemia is severe. Screening for HPS could enhance detection of OLT candidates with sufficient hypoxemia to merit higher priority for transplant and thereby decrease mortality. However, the cost-effectiveness of such an approach has not been assessed. Our objective was to perform a cost-effectiveness analysis from a third-party payer's perspective of screening for HPS in liver OLT candidates. The costs and outcomes of 3 different strategies were compared: (1) no screening, (2) screening patients with a validated dyspnea questionnaire, and (3) screening all patients with pulse oximetry. Arterial blood gas analyses and contrast echocardiography were performed in patients with dyspnea or a pulse oximetry (SpO(2)) < or =97% to define the presence of HPS. A Markov model was constructed simulating the natural history of cirrhosis in a cohort of patients 50 years old over a time horizon of their remaining life expectancy. Transition probabilities were obtained from published data available through Medline and U.S. vital statistics. Costs represented Medicare reimbursement data at our institution. Costs and health effects were discounted at a 3% annual rate. No screening was associated with a total cost of 291,898 dollars and a life expectancy of 11.131 years. Screening with pulse oximetry was associated with a cost of 299,719 dollars and a life expectancy of 12.27 years. Screening patients with the dyspnea-fatigue index was associated with a cost and life expectancy of 300,278 dollars and 12.28 years, respectively. The incremental cost-effectiveness ratio of screening with pulse oximetry (compared to no screening) was 6,867 dollars per life year gained, whereas that of the dyspnea-fatigue index (compared to pulse oximetry) was 55,900 dollars per life year gained. The cost-effectiveness of screening depended on the prevalence and severity of HPS, and the choice of screening strategy was dependent on the sensitivity of the screening modality. In conclusion, screening for HPS, especially with pulse oximetry, is a cost-effective strategy that improves survival in transplant candidates predominantly by targeting the transplant to the subgroup of patients most likely to benefit. The utility of screening depends on the prevalence and severity of HPS in the target population.

Liver transplantation of a child with child a cirrhosis and severe hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is a clinical state defined by a chronic hepatic disorder, intrapulmonary vascular dilatation, and altered gas exchange resulting in hypoxemia. Cirrhosis of the liver is the most common condition associated with HPS. A 3-year-old boy who presented with end-stage liver disease and severe hepatopulmonary syndrome underwent orthotopic liver transplantation (OLT). The findings of HPS resolved immediately after OLT. His status is within normal limits at 6 months after liver transplantation.

Hepatopulmonary syndrome

The hepatopulmonary syndrome (HPS) is an important and often under-recognized vascular complication of cirrhosis and portal hypertension characterized by pulmonary vascular dilatation, which results in hypoxemia. This syndrome is identified in as many as 20% of patients who are evaluated for orthotopic liver transplantation (OLT), and it has recently been found to increase mortality in affected patients, particularly when hypoxemia is severe. Currently, OLT is the only therapy established to reverse intrapulmonary vasodilatation, although postoperative mortality is increased in patients with severe hypoxemia. No randomized controlled trials of pharmacologic therapies have been undertaken, but supplemental oxygen improves oxygenation. Data derived from case reports, small studies, and experimental models suggest that pharmacologic therapies may be effective. In cirrhotic patients with HPS, particularly those with moderate hypoxemia (PaO2 < 60 mmHg), OLT should be considered prior to the development of severe deoxygenation. Supplemental oxygen should be given to patients with a PaO2 < 60 mmHg or those with exercise oxygen desaturation. For those patients with mild hypoxemia or those who are not OLT candidates, a trial of pharmacologic treatment may be considered.

Development of pulmonary hypertension in 5 patients after pediatric living-donor liver transplantation: de novo or secondary?

The development of portopulmonary hypertension (PH) in a patient with end-stage liver disease is related to high cardiac output and hyperdynamic circulation. However, PH following liver transplantation is not fully understood. Of 617 pediatric patients receiving transplants between June 1990 and March 2004, 5 (median age 12 yr, median weight 24.5 kg) were revealed to have portopulmonary hypertension (PH) after living-donor liver transplantation (LDLT), as confirmed by echocardiography and/or right heart catheterization. All children underwent LDLT for post-Kasai biliary atresia. In 2 patients with refractory biliary complications, PH developed following portal thrombosis; 2 with stable graft function, who had had intrapulmonary shunting (IPS) before LDLT, were found to have PH in spite of overcoming liver dysfunction due to hepatitis. PH developed shortly after distal splenorenal shunting in 1 patient, who suffered liver cirrhosis due to an intractable outflow blockage. The onset of PH ranged from 2.8 to 11 yr after LDLT, and mean pulmonary artery pressure (mPAP) estimated by echocardiography at the time of presentation ranged from 43 to 120 mmHg. Three of the 5 patients are alive under prostaglandin I2 (PGI2) treatment. Of these, 1 is prepared for retransplantation for an intractable complications of liver allograft, while the other 2 with satisfactory grafts are being considered for lung transplantation. Even after LDLT, PH can develop with portal hypertension. Periodic echocardiography is essential for early detection and treatment of PH especially in the recipients with portal hypertension not only preoperatively but also postoperatively.

Hepatopulmonary syndrome in patients with chronic liver disease: role of pulse oximetry

Background

Hepatopulmonary syndrome (HPS) is a rare complication of liver diseases of different etiologies and may indicate a poor prognosis. Therefore, a simple non-invasive screening method to detect HPS would be highly desirable. In this study pulse oximetry was evaluated to identify patients with HPS.

Methods

In 316 consecutive patients with liver cirrhosis (n = 245), chronic hepatitis (n = 69) or non-cirrhotic portal hypertension (n = 2) arterial oxygen saturation (SaO₂) was determined using a pulse oximeter. In patients with SaO₂ ≤92% in supine position and/or a decrease of ≥4% after change from supine to upright position further diagnostic procedures were performed, including contrast-enhanced echocardiography and perfusion lung scan.

Results

Seventeen patients (5.4%) had a pathological SaO₂. Four patients (1.3%) had HPS. HPS patients had a significant lower mean SaO₂ in supine (89.7%, SD 5.4 vs. 96.0%, SD 2.3; p = 0.003) and upright position (84.3%, SD 5.0 vs. 96.0%, SD 2.4; p = 0.001) and had a lower mean PaO₂ (56.2 mm Hg, SD 15.2 vs. 71.2 mm Hg, SD 20.2; p = 0.02) as compared to patients without HPS. The mean ΔSaO₂ (difference between supine and upright position) was 5.50 (SD 7) in HPS patients compared to non-HPS patients who showed no change (p = 0.001). There was a strong correlation between shunt volume and the SaO₂ values (R = -0.94).

Conclusion

Arterial SaO₂ determination in supine and upright position is a useful non-invasive screening test for HPS and correlates well with the intrapulmonary shunt volume.

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 m² 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 non-responder 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.

Significance of Hypoxemia Screening in Candidates for Liver Transplantation: Our Experience

Hepatopulmonary syndrome (HPS) is recognized as one of the causes of hypoxemia in patients with chronic liver disease. This complication is responsible for increased mortality and increased perioperative risk in liver transplantation candidates. Recent data from the literature suggest extending the screening for HPS to all candidates for liver transplantation. The aim of this retrospective study was to evaluate the incidence of hypoxemia among a population of patients awaiting liver transplantation. Using pulse oximetry as a screening tool for hypoxemia, 39 of 198 patients (20%) were hypoxemic. The results of this study confirmed the importance of screening for hypoxemia among patients awaiting liver transplantation. In these patients, a more accurate evaluation of respiratory function should be performed to confirm or exclude the diagnosis of HPS.

Clinical predictors and characteristics of patients with chronic liver disease and intrapulmonary shunts

BACKGROUND

Intrapulmonary shunting (IPS) is a well-described phenomenon in chronic liver disease but its significance is not known.

HYPOTHESIS

The study was undertaken to enhance our understanding of the characteristics and prevalence of IPS.

METHODS

We retrospectively studied 204 consecutive patients with end-stage chronic liver disease who underwent a dobutamine stress echocardiogram, along with a saline contrast bubble study, as part of their pretransplant evaluation.

RESULTS

Intrapulmonary shunting of any degree was present in 56.4% of patients. Patients with IPS were more likely to report alcohol use and less likely to have diabetes mellitus. Patients in Child-Pugh classification C were more likely to have IPS than those with classification A or B. The resting room air PaO2 levels were significantly lower in patients with grade 3-4 IPS than in those with grade 1-2. Elevated estimated pulmonary systolic pressure on echocardiography was more prevalent in patients with than in those without IPS.

CONCLUSIONS

A majority of patients with end-stage chronic liver disease undergoing transplant evaluation have IPS. There are important baseline differences between patients with and without IPS. The presence of IPS is associated with increased severity of chronic liver disease. Further study is required to define the prognostic significance of IPS and its impact on future liver transplantation.

Hepatopulmonary syndrome

The hepatopulmonary syndrome is an increasingly important vascular complication of cirrhosis where microvascular dilatation impairs arterial oxygenation in the setting of liver disease. This syndrome is identified in as many as 20% of patients evaluated for liver transplantation and results in increased mortality. No clearly effective medical therapies are available, and liver transplantation is the only established treatment. Pathophysiologic insights obtained from experimental models may lead to the development of novel and effective medical treatments.

[Hepatopulmonary syndrome: relationship with liver dysfunction and systemic hemodynamic disorder]

BACKGROUND AND OBJECTIVE

The hepatopulmonary syndrome (HPS) causes an increased alveolar to arterial gradient of oxygen and in advanced phases hypoxemia, as the result of pulmonary vasodilation. In liver cirrhosis, it has been demonstrated the existence of splachnic vasodilation and also in other vascular beds. Our main objectives were to know the hemodynamic status, the renal function and the condition of some humoral systems in patient diagnosed of HPS.

PATIENTS AND METHOD

We studied consecutively 32 cirrhotic patients Divided in two groups, a group of 18 cirrhotic patients with normal gaseous exchange (NGE), and another group of 14 cirrhotic patients diagnosed of HPS by contrast-enhanced transthoracic echocardiography and/or lung and brain scintigraphy with 99Tc albumin macroaggregates. They were all in rest in bed, upon alcohol and tobacco abstinence and on a diet of 50 mEq of sodium. Cardiovascular drugs were all withheld during 4 days in order to reach steady state.

RESULTS

Patients of the HPS group were characterized by a more advanced index of Child-Pugh and presence of clubbing and vascular spiders. They presented a greater degree of hypoxemia in a sitting position, greater hypocapnia and smaller transference factor values (TLCO). They also showed a hyperkinetic circulatory condition characterized by smaller arterial blood pressure, greater cardiac index, smaller vascular resistances and greater femoral flows, with smaller clearance of creatinine, elimination of urinary sodium, urinary volume/24 h and an increased plasmatic volume, accompanied with a greater activation of the renin-angiotensin-aldosterone axis and a greater urinary elimination of nitrites and nitrates.

CONCLUSIONS

The pulmonary vasodilation that explains the HPS is a constitutive part of the systemic vasodilation occurring in liver cirrhosis, and it is related to the degree of liver dysfunction as measured by the classification of Child-Pugh. The greater activation of the renin-aldosterone system and the rise of the plasmatic volume express a highest grade of arterial underfilling caused by an increment in the nitric oxide production.

Carboxyhemoglobin levels in cirrhotic patients with and without hepatopulmonary syndrome

BACKGROUND AND AIMS

Heme oxygenase (HO) catalyzes hemoglobin into bilirubin, iron, and carbon monoxide (CO), a known vasodilator. HO expression and CO production as measured by blood carboxyhemoglobin (COHb) levels increase in experimental hepatopulmonary syndrome (HPS) and contribute to vasodilatation. Whether CO contributes to HPS in humans is unknown. Our aim was to assess if arterial COHb levels are increased in cirrhotic patients with HPS relative to those without HPS.

METHODS

We collected data prospectively in stable nonsmoking outpatients with cirrhosis. Demographic and clinical data and room-air arterial blood gases were collected and analyzed. HPS was diagnosed using established criteria.

RESULTS

A total of 159 patients were studied. HPS was present in 27 (17%) patients. Mean age was 52 +/- 9 years, 54% were men, and hepatitis C and/or alcohol were the most common causes (53%). Fourteen percent were Child-Pugh class A, 53% were Child-Pugh class B, and 33% were Child-Pugh class C. Demographic and clinical features were similar between HPS and non-HPS patients except for the Child-Pugh score, which was lower in patients with HPS. Arterial Pa o 2 levels were lower and the alveolar-arterial oxygen gradient was higher in patients with HPS ( P < .001). COHb levels were increased in HPS relative to non-HPS ( P < .001) and correlated with Pa o 2 ( P < .001) and Aa po 2 ( P < .001) levels.

CONCLUSIONS

COHb levels are increased in cirrhotic patients with HPS and correlate with gas exchange abnormalities. These results are consistent with findings in experimental HPS and suggest that CO may contribute to human HPS.

Intra-pulmonary shunt and pulmonary gas exchange during exercise in humans

In young, healthy people the alveolar-arterial P(O(2)) difference (A-aDO(2)) is small at rest, but frequently increases during exercise. Previously, investigators have focused on ventilation/perfusion mismatch and diffusion abnormalities to explain the impairment in gas exchange, as significant physiological intra-pulmonary shunt has not been found. The aim of this study was to use a non-gas exchange method to determine if anatomical intra-pulmonary (I-P) shunts develop during exercise, and, if so, whether there is a relationship between shunt and increased A-aDO(2). Healthy male participants performed graded upright cycling to 90% while pulmonary arterial (PAP) and pulmonary artery wedge pressures were measured. Blood samples were obtained from the radial artery, cardiac output was calculated by the direct Fick method and I-P shunt was determined by administering agitated saline during continuous 2-D echocardiography. A-aDO(2) progressively increased with exercise and was related to (r = 0.86) and PAP (r = 0.75). No evidence of I-P shunt was found at rest in the upright position; however, 7 of 8 subjects developed I-P shunts during exercise. In these subjects, point bi-serial correlations indicated that I-P shunts were related to the increased A-aDO(2) (r = 0.68), (r = 0.76) and PAP (r = 0.73). During exercise, intra-pulmonary shunt always occurred when A-aDO(2) exceeded 12 mmHg and was greater than 24 l min(-1). These results indicate that anatomical I-P shunts develop during exercise and we suggest that shunt recruitment may contribute to the widened A-aDO(2) during exercise.

Portopulmonary hypertension and hepatopulmonary syndrome

The clinically and pathophysiologically distinct entities of portopulmonary hypertension and hepatopulmonary syndrome occur in a substantial proportion of patients who have advanced liver disease of different causes. These disorders are notoriously underdiagnosed, but they have a substantial impact on survival and require focused treatment. Abnormal intrapulmonary vascular dilatation, the hallmark of hepatopulmonary syndrome, can cause profound hypoxaemia that can be very difficult to treat. By contrast, portopulmonary hypertension results from excessive pulmonary vasoconstriction and vascular remodelling that eventually leads to right-heart failure. Insights into the pathogeneses of these syndromes have led to novel therapeutic approaches. However, in severely affected patients, effective treatment remains a difficult task. In selected patients, liver transplantation represents the only treatment option, but the decision to do isolated liver transplantation is particularly challenging in patients who have severe pulmonary disease involvement. Data from several centres have contributed to provide criteria that allow improved prediction of which patients may, or may not, benefit from liver transplantation alone.

The significance of hepatopulmonary syndrome in liver transplantation

The objective of the study is to determine the diagnostic role of pulmonary functional tests and perfusion pulmonary scintigraphy for quantifying the oxygenation and vascular abnormality in patients with liver cirrhosis. The prospective study included 70 patients with liver cirrhosis. Arterial blood gases analysis were performed in both supine and sitting positions while inhaling room air, and 15 minutes after exposure of hyperoxic mixture. Perfusion pulmonary scintigraphy using albumin macroagregate labelled with radioactive technetium (99mTc-MAA) was performed for the visualisation of intrapulmonary vascular dilatation. The diagnosis of hepatopulmonary syndrome was made in 10 (14.3%) patients. The patients with hepatopulmonary syndrome had severe hypoxemia (Pa,O2 7.41 +/- 1.81 kPa), and poor response to 100% oxygen inhalation (Pa,O2 21.07 +/- 14.41 kPa) and higher alveolo-arterial gradient (5.73 +/- 2.65 kPa). Radioisotope marker 99mTc-MAA skipped intrapulmonary circulation in all patients with HPS and in no one without pulmonary vascular dilatations. The combined approach of 100% inspired oxygen and perfusion pulmonary scintigraphy may identify early oxygenation disorders and alter the priority for liver transplantation, especially in view of potential syndrome resolution.

Reversed Intrapulmonary Right-to-Left Shunt After Banding of the Patent Ductus Venosus

Diffuse pulmonary microvascular arteriovenous communication developed in an 8-year-old girl with a patent ductus venosus. Tc-99m macroaggregated albumin (MAA) pulmonary perfusion scintigraphy with total-body imaging demonstrated multiple lung perfusion deficits and abnormal tracer uptake in systemic organs with hepatic radioactivity greater than the kidneys, suggesting the presence of right-to-left shunt and abnormal hepatic hemodynamics. I-123 iodoamphetamine transrectal portal scintigraphy revealed a large portosystemic venous shunt. The follow-up Tc-99m MAA perfusion scans after banding of the patent ductus venosus revealed partial improvement of the perfusion deficits and right-to-left shunt, indicating the possible reversibility of this pulmonary shunt complication.

Prognostic significance of the hepatopulmonary syndrome in patients with cirrhosis

BACKGROUND AND AIMS

The hepatopulmonary syndrome (HPS) has been defined by chronic liver disease, arterial deoxygenation, and widespread intrapulmonary vasodilation. Mortality of patients with HPS is considered to be high, but the effect of HPS on survival in patients with cirrhosis remains unclear.

METHODS

A total of 111 patients with cirrhosis were studied prospectively by using transthoracic contrast echocardiography for detection of pulmonary vasodilation, blood gas analysis, and pulmonary function test. Twenty different clinical characteristics and survival times were noted.

RESULTS

Twenty-seven patients (24%) had HPS. Their mortality was significantly higher (median survival, 10.6 months) compared with patients without HPS (40.8 mo, P < 0.05), even after adjusting for liver disease severity (2.9 vs. 14.7 months in Child-Pugh class C with [n = 15] and without HPS [n = 35, P < 0.05]; 35.3 vs. 44.5 months in Child-Pugh class B with [n = 7] and without HPS [n = 23, P = NS]), and exclusion of patients who underwent liver transplantation during follow-up (median survival 4.8 vs. 35.2 months, P = 0.005). Causes of death were mainly nonpulmonary and liver-related in the 19 patients with and the 35 patients without HPS who died. In multivariate analysis, HPS was an independent predictor of survival besides age, Child-Pugh class, and blood urea nitrogen. Mortality correlates with severity of HPS.

CONCLUSIONS

The presence of HPS independently worsens prognosis of patients with cirrhosis. This should influence patient management and scoring systems and accelerate the evaluation process for liver transplantation.

Liver transplantation for hepatopulmonary syndrome: a ten-year experience in Paris, France

BACKGROUND

Although the possibility of reversing hepatopulmonary syndrome (HPS) after liver transplantation is now well established, the proportion of patients in whom reversibility is observed and the time to resolution of HPS remain uncertain.

METHODS

We analyzed the outcome of all adult patients with HPS who underwent orthotopic liver transplantation in all the liver transplant centers in Paris, during a 10-year period.

RESULTS

Twenty-three adult patients (median age, 47 years; range, 14-64) underwent transplantation in four institutions. Median PaO(2) was 52 (range, 32-67) mm Hg and median alveolar-arterial oxygen gradient was 66 mm Hg. When patients were breathing 100% O(2), median PaO(2) was 310 (range, 74-663) mm Hg. Median isotopic shunt ratio was 33% (range, 0-80%). The overall mortality during the study period was 30.5% (7/23). Perioperative mortality was 8.5%, whereas late mortality was 22%. None of the preoperative characteristics of HPS (isotopic shunt ratio, PaO(2) on room air or on 100% oxygen) was associated with overall postoperative mortality. Of the 21 patients surviving the perioperative period (median follow-up, 17 months; range, 0.5-72), a decrease in alveolar-arterial oxygen gradient of at least 5 mm Hg and at least 10 mm Hg was observed in 21 of 21 and in 18 of 21 patients, respectively, with great variations in the time of improvement. The threshold of 70 mm Hg was reached in 15 patients. The lower the preoperative PaO(2), the longer the time to reach this point.

CONCLUSION

Our data strongly support the role of orthotopic liver transplantation in adult patients with HPS, regardless of its severity.

Hepatopulmonary syndrome in poorly compensated postnecrotic liver cirrhosis by hepatitis B virus in Korea

BACKGROUND

Hepatopulmonary syndrome (HPS) refers to the association of hypoxemia, intrapulmonary shunting and chronic liver disease. But there is no clear data about the prevalence of HPS in postnecrotic liver cirrhosis by hepatitis B virus (HBV), the most common cause of liver disease in Korea. The aim of this study was to investigate the prevalence of HPS in poorly compensated postnecrotic liver cirrhosis by HBV, and the correlation of the hepatopulmonary syndrome with clinical aspects of postnecrotic liver cirrhosis by HBV.

METHODS

Thirty-five patients underwent pulmonary function test, arterial blood gas analysis and contrast-enhanced echocardiography. All patients were diagnosed as HBV-induced Child class C liver cirrhosis and had no evidence of intrinsic cardiopulmonary disease.

RESULTS

Intrapulmonary shunt was detected in 6/35 (17.1%) by contrast-enhanced echocardiography. Two of six patients with intrahepatic shunts had significant hypoxemia (PaO2 < 70 mmHg) and four showed increased alveolar-arterial oxygen gradient over 20 mmHg. Only cyanosis could reliably distinguish between shunt positive and negative patients.

CONCLUSIONS

The prevalence of intrapulmonary shunt in poorly compensated postnecrotic liver cirrhosis by HBV was 17.1% and the frequency of hepatopulmonary syndrome was relatively low (5.7%). 'Subclinical' hepatopulmonary syndrome (echocardiographically positive intrapulmonary shunt but without profound hypoxemia) exists in 11.4% of cases with poorly compensated postnecrotic liver cirrhosis by HBV. Cyanosis is the only reliable clinical indicator of HPS of HBV-induced poorly compensated liver cirrhosis. Further studies are required to determine if the prevalence and clinical manifestations of HPS varies with etiology or with geographical and racial differences.

The hepatopulmonary syndrome

The hepatopulmonary syndrome is a triad of liver disease, increased alveolar-arterial oxygen gradient and intrapulmonary vascular dilatations. Manifestations include orthodeoxia, platypnoea and hyperdynamic circulation. Intrapulmonary vascular abnormalities, perhaps mediated by nitric oxide, cause hypoxaemia by shunting, a perfusion-diffusion defect, and ventilation-perfusion mismatching. Contrast-enhanced echocardiography is the method of choice for demonstrating pulmonary vascular abnormalities, although perfusion lung scanning is a more specific and sensitive test. Angiography is best reserved for patients with poor response to 100% oxygen and defines whether vascular dilatations are of the diffuse 'spongy' type or, less commonly, discrete arteriovenous communications amenable to embolization. About 80% of patients with the hepatopulmonary syndrome eventually have improved oxygenation after liver transplantation, thereby making worsening hypoxaemia the primary indication for transplantation in many instances. Nevertheless, severe hypoxaemia carries a peri-operative mortality of 30% and reliable predictors of successful outcome after transplantation remain to be determined.

Clinical significance of ventilation/perfusion scans in collagen disease patients

The purpose of this study was to detect disturbances in pulmonary circulation in collagen disease patients by means of a non-invasive technique.

METHODS

Ventilation/perfusion scans with 133Xe gas and 99mTc-macroaggregated albumin (MAA) were performed in 109 patients with various collagen diseases. Functional images of V, Vol, Q and V/Q ratio were obtained at total lung capacity. Wash-out time was calculated from the wash-out curve. Whole body scans were performed in 65 patients to evaluate intra-pulmonary shunts.

RESULTS

Increased V/Q areas were observed in 74 patients (67.9%), suggesting some impairment of pulmonary perfusion. Decreased perfusion, probably due to vasculitis or intravascular microcoagulation, was observed often, even in patients without pulmonary fibrosis. Shunt ratios over 10% were observed in 8 of the 65 patients (12.3%), indicating formation of PA-PV shunts secondary to peripheral vascular impairment. Wash-out time was prolonged in 37 patients (33.9%), shortened in 18 (16.5%), and within the normal range in 54 (49.6%). The prolonged and normal wash-out times in the patients with pulmonary fibrosis may represent obstructive changes in the small airways superimposed on the fibrosis.

CONCLUSION

Ventilation/perfusion scans are a very useful tool for evaluating collagen lung diseases, and they might contribute to treatment decisions for the patients.

Hepatopulmonary syndrome: a prospective study of relationships between severity of liver disease, PaO(2) response to 100% oxygen, and brain uptake after (99m)Tc MAA lung scanning

BACKGROUND

Because of the spectrum of intrapulmonary vascular dilation that characterizes hepatopulmonary syndrome (HPS), PaO(2) while breathing 100% oxygen varies. Abnormal extrapulmonary uptake of (99m)Tc macroaggregated albumin (MAA) after lung perfusion is common.

GOAL

To describe relationships between (1) severity of liver disease measured by the Child-Pugh (CP) classification; (2) PaO(2) while breathing room air (RA) and 100% oxygen on 100% oxygen; and (3) extrapulmonary (brain) uptake of (99m)Tc MAA after lung scanning.

METHODS AND PATIENTS

We prospectively measured PaO(2) on RA, PaO(2) on 100% oxygen, and brain uptake after lung perfusion of (99m)Tc MAA in 25 consecutive HPS patients.

RESULTS

Mean PaO(2) on RA, PaO(2) on 100% oxygen, PaCO(2) on RA, and (99m)Tc MAA brain uptake were similar when categorized by CP classification. Brain uptake was abnormal (> or = 6%) in 24 patients (96%). Brain uptake was 29 +/- 20% (mean +/- SD) and correlated inversely with PaO(2) on RA (r = -0.57; p<0.05) and PaO(2) on 100% oxygen (r = -0.41; p<0.05). Seven patients (28%) had additional nonvascular pulmonary abnormalities and lower PaO(2) on 100% oxygen (215+/-133 mm Hg vs 391+/-137 mm Hg; p<0.007). Eight patients (32%) died. Mortality in patients without coexistent pulmonary abnormalities was associated with greater brain uptake of (99m)Tc MAA (48+/-18% vs 25+/-20%; p<0.04) and lower PaO(2) on RA (40+/-7 mm Hg vs 57+/-11 mm Hg; p<0.001).

CONCLUSION

The degree of hypoxemia associated with HPS was not related to the CP severity of liver disease. HPS patients with additional nonvascular pulmonary abnormalities exhibited lower PaO(2) on 100% oxygen. Mortality was associated with lower PaO(2) on RA, and with greater brain uptake of (99m)Tc MAA.