Nitric oxide and carbon monoxide lung transfer in patients with advanced liver cirrhosis

Multimodal Screening for Pulmonary Arterial Hypertension in Systemic Scleroderma: Current Methods and Future Directions

Systemic sclerosis (SSc) is an immuno-inflammatory rheumatic disease that can affect both the skin and internal organs through fibrosis. Pulmonary arterial hypertension (PAH) is one of the most severe secondary complications. Structural changes in the vascular bed lead to increased pressures in the pulmonary circulation, severely impacting the right heart and significantly affecting mortality. The gold standard for diagnosing PAH is right heart catheterization (RHC), an invasive method for measuring cardiac pressure. Due to the high risk of complications, procedural difficulties, and significant costs, non-invasive screening for SSc-PAH has garnered significant interest. Echocardiography is likely the most important screening tool, providing structural and functional information about the right heart through measurements that have proven their utility over time. In addition to imagistic investigations, serum biomarkers aid in identifying patients at risk for PAH and can provide prognostic information. Currently, well-known serum biomarkers (NT-proBNP, uric acid) are used in screening; however, in recent years, researchers have highlighted new biomarkers that can enhance diagnostic accuracy for SSc patients. Pulmonary involvement can also be assessed through pulmonary function tests, which, using established thresholds, can provide additional information and help select patients requiring RHC. In conclusion, given the invasiveness of RHC, non-invasive screening methods are particularly important for SSc patients.

Pulmonary function testing in patients with liver cirrhosis (Review)

Liver cirrhosis is a common long-term outcome of chronic hepatic inflammation. Patients with liver cirrhosis may also have pulmonary complications. There are several reasons for pulmonary dysfunction in liver cirrhosis, including intrinsic cardiopulmonary dysfunction unrelated to liver disease and specific disorders related to the presence of liver cirrhosis and/or portal hypertension. The most prevalent and clinically significant pulmonary complications are hepatic hydrothorax, hepatopulmonary syndrome, spontaneous pulmonary empyema and portopulmonary hypertension. Pulmonary function tests (PFTs) have traditionally been used to assess the lung function of patients with liver cirrhosis. To the best of our knowledge, the present review is the first to detail all types of PFTs performed in patients with liver cirrhosis and discuss their clinical significance. Patients with liver cirrhosis have reduced values of spirometric parameters, diffusion capacity for carbon monoxide (DLCO), lung volumes, maximal inspiratory pressure and maximal expiratory pressure. Furthermore, they have a higher closing volume, a greater airway occlusion pressure 0.1 sec after the onset of inspiratory flow and greater exhaled nitric oxide values. In order to improve pulmonary function, patients with ascites may require therapeutic paracentesis. Such findings should be considered when evaluating individuals with liver disease, particularly those who may require surgery. Poor lung function, particularly restrictive lung disease, can have an impact on post-transplant outcomes, such as ventilator time, length of hospital duration and post-operative pulmonary complications; thus, the transplant care team needs to be aware of its prevalence and relevance.

Double gas transfer factors (DLCO-DLNO) at rest in patients with congenital heart diseases correlates with their ventilatory response during maximal exercise

Aim

Exercise capacity is altered in congenital heart diseases (CHD) with potentially impaired pulmonary perfusion adaptation during exercise, such as in single ventricle or in significant pulmonary regurgitation. This study aimed to evaluate the value of double gas transfer factor analysis, at rest in conjunction with postural manoeuvres, to explore the various components of pulmonary gas transfer and its association with exercise capacity.

Methods

A total of 40 subjects (24 CHD, 16 controls) underwent a combined measurement of lung diffusing capacity for carbon monoxide and nitric oxide (DLCO-DLNO) to determine pulmonary membrane diffusion (Dm) and Vcap, in sitting then supine position. CHD patients performed a maximal cardiopulmonary exercise test.

Results

Compared to normal controls, the CHD group's DLNO, DLCO, Vcap, and alveolar volume (AV) at rest, in the sitting position were depressed, whereas the DLCO/AV and DLNO/AV were similar. The magnitude of Dm and Vcap adaptation induced by postural change was similar in both groups, indicating a preserved pulmonary capillary recruitment capacity in CHD. In the CHD group, at rest, for each ml of postural-induced increase in Vcap we observed during exercise a VE/VCO2 slope decrease of 0.46 (95% CI[0.83; 0.098]), indicating a better ventilatory response to exercise.

Conclusion

CHD patients with impaired pulmonary circulation have a reduced Dm and Vcap mainly due to decreased pulmonary volume but maintain a normal capacity to adapt these parameters through a simple recruitment manoeuver. Vcap adaptation evaluated at rest predicts the level of ventilatory efficiency during exercise, which represents a main limiting factor in these CHD patients.

Lung Diffusing Capacities (DL ) for Nitric Oxide (NO) and Carbon Monoxide (CO): The Evolving Story

Nitric oxide and carbon monoxide diffusing capacities (D_LNO and D_LCO ) obey Fick's First Law of Diffusion and the basic principles of chemical kinetic theory. NO gas transfer is dominated by membrane diffusion (D_M ), whereas CO transfer is limited by diffusion plus chemical reaction within the red cell. Marie Krogh, who pioneered the single-breath measurement of D_LCO in 1915, believed that the combination of CO with red cell hemoglobin (Hb) was instantaneous. Roughton and colleagues subsequently showed, in vitro, that the reaction rate was finite, and prolonged in the presence of high P O 2 . Roughton and Forster (R-F) proposed that the resistance to transfer (1/D_L ) was the sum of the membrane resistance (1/D_M ) and (1/θVc), the red cell resistance (θ being the CO or NO conductance for blood uptake and Vc the capillary volume). From this R-F equation, D_M for CO and Vc can be solved with simultaneous NO and CO inhalation. At near maximum exercise, D_MCO and Vc for normal subjects were 88% and 79%, respectively, of morphometric values. The validity of these calculations depends on the values chosen for θ for CO and NO, and on the diffusivity of NO versus CO. Recent mathematical modeling suggests that θ for NO is "effectively" infinite because NO reacts only with Hb in the outer 0.1 μM of the red cell. An "infinite θ_NO " recalculation reduced D_MCO to 53% and increased Vc to 95% of morphometric values. © 2020 American Physiological Society. Compr Physiol 10:73-97, 2020.

Combined diffusing capacity for nitric oxide and carbon monoxide as predictor of bronchiolitis obliterans syndrome following lung transplantation

BACKGROUND

There is a need for non-invasive parameters that are sensitive to the development of the bronchiolitis obliterans syndrome (BOS) in lung transplantation (LTx) patients. We studied whether the pulmonary diffusing capacity for inhaled nitric oxide is capable of detecting BOS stages.

METHODS

Sixty-one LTx patients were included into this cross-sectional study (19/29/7/3/3 in BOS stages 0/0-p/1/2/3). For analysis stages 0/0-p versus 1/2/3 ("BOS binary-early"), and stages 0/0-p/1 versus 2/3 ("BOS binary-late") were summarized. Measurements of the combined diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) were compared with spirometry and bodyplethysmography, and their relative importance was evaluated by discriminant analysis.

RESULTS

Regarding the recognition of "BOS binary-early", among spirometric parameters forced expiratory volume in 1 s (FEV1) was best, among bodyplethysmographic parameters airway resistance, and among diffusing parameters DLNO. Regarding "BOS binary-late", DLNO was inferior to bodyplethysmographic parameters.

CONCLUSION

Although the study comprised only measurements at a single time point and no follow-up, DLNO outperformed FEV1, the time course of which is used in detecting BOS. Together with its pathophysiological plausibility, this result suggests that the measurement of DLNO, possibly over time, could be an easily applicable tool for the monitoring of LTx patients and should be evaluated in larger studies.

Hepatopulmonary Disorders: Gas Exchange and Vascular Manifestations in Chronic Liver Disease

This review concentrates on the determinants of gas exchange abnormalities in liver-induced pulmonary vascular disorders, more specifically in the hepatopulmonary syndrome. Increased alveolar-arterial O₂ difference, with or without different levels of arterial hypoxemia, and reduced diffusing capacity represent the most characteristic gas exchange disturbances in the absence of cardiac and pulmonary comorbidities. Pulmonary gas exchange abnormalities in the hepatopulmonary syndrome are unique encompassing all three pulmonary factors determining arterial PO₂ , that is, ventilation-perfusion imbalance, increased intrapulmonary shunt and oxygen diffusion limitation that, combined, interplay with two relevant nonpulmonary determinants, that is, increased total ventilation and high cardiac output. Behind the complexity of this lung-liver association there is an abnormal pulmonary vascular tone that combines inhibition of hypoxic pulmonary vasoconstriction with a reduced (or blunted) hypoxic vascular response. The pathology and pathobiology include the presence of intrapulmonary vascular dilatations with or without pulmonary vascular remodeling, i.e. angiogenesis. Liver transplantation, the only effective therapeutic approach to successfully improve and resolve the vast majority of complications induced by the hepatopulmonary syndrome, along with a large list of frustrating pharmacologic interventions, are also reviewed. Another liver-induced pulmonary vascular disorder with less gas exchange involvement, such as portopulmonary hypertension, is also considered. © 2018 American Physiological Society. Compr Physiol 8:711-729, 2018.

Combined measurement of carbon monoxide and nitric oxide lung transfer does not improve the identification of pulmonary hypertension in systemic sclerosis

Screening is important to determine whether patients with systemic sclerosis (SSc) have pulmonary hypertension because earlier pulmonary hypertension treatment can improve survival in these patients. Although decreased transfer factor of the lung for carbon monoxide (TLCO) is currently considered the best pulmonary function test for screening for pulmonary hypertension in SSc, small series have suggested that partitioning TLCO into membrane conductance (diffusing capacity) for carbon monoxide (DMCO) and alveolar capillary blood volume (VC) through combined measurement of TLCO and transfer factor of the lung for nitric oxide (TLNO) is more effective to identify pulmonary hypertension in SSc patients compared with TLCO alone. Here, the objective was to determine whether combined TLCO–TLNO partitioned with recently refined equations could more accurately detect pulmonary hypertension than TLCO alone in SSc.

For that purpose, 572 unselected consecutive SSc patients were retrospectively recruited in seven French centres.

Pulmonary hypertension was diagnosed with right heart catheterisation in 58 patients. TLCO, TLNO and VC were all lower in SSc patients with pulmonary hypertension than in SSc patients without pulmonary hypertension. The area under the receiver operating characteristic curve for the presence of pulmonary hypertension was equivalent for TLCO (0.82, 95% CI 0.79–0.85) and TLNO (0.80, 95% CI 0.76–0.83), but lower for VC (0.75, 95% CI 0.71–0.78) and DMCO (0.66, 95% CI 0.62–0.70).

Compared with TLCO alone, combined TLCO–TLNO does not add capability to detect pulmonary hypertension in unselected SSc patients.

Standardisation and application of the single-breath determination of nitric oxide uptake in the lung

Diffusing capacity of the lung for nitric oxide (D_LNO), otherwise known as the transfer factor, was first measured in 1983. This document standardises the technique and application of single-breath D_LNO This panel agrees that 1) pulmonary function systems should allow for mixing and measurement of both nitric oxide (NO) and carbon monoxide (CO) gases directly from an inspiratory reservoir just before use, with expired concentrations measured from an alveolar "collection" or continuously sampled via rapid gas analysers; 2) breath-hold time should be 10 s with chemiluminescence NO analysers, or 4-6 s to accommodate the smaller detection range of the NO electrochemical cell; 3) inspired NO and oxygen concentrations should be 40-60 ppm and close to 21%, respectively; 4) the alveolar oxygen tension (P_AO2 ) should be measured by sampling the expired gas; 5) a finite specific conductance in the blood for NO (θNO) should be assumed as 4.5 mL·min^-1·mmHg^-1·mL^-1 of blood; 6) the equation for 1/θCO should be (0.0062·P_AO2 +1.16)·(ideal haemoglobin/measured haemoglobin) based on breath-holding P_AO2 and adjusted to an average haemoglobin concentration (male 14.6 g·dL^-1, female 13.4 g·dL^-1); 7) a membrane diffusing capacity ratio (D_MNO/D_MCO) should be 1.97, based on tissue diffusivity.

Utilising exhaled nitric oxide information to enhance diagnosis and therapy of respiratory disease - current evidence for clinical practice and proposals to improve the methodology

INTRODUCTION

A non-invasive tool to diagnose respiratory diseases and to follow treatment has long been looked-for. Exhaled nitric oxide (NO) is a promising marker of inflammation in asthma but nearly 25-years of research has shown that it works in only certain endotypes of asthma. The modelling of NO dynamics of the lung can give more information than a single F_ENO value. Areas covered: The estimation of the NO production in the conducting airways and in the gas exchange area has given new insight of the NO production in diseases beyond asthma. In this article, we discuss the importance of methodology for NO measurement in the exhaled breath and the indication of applying this technique to detect respiratory disorders. This narrative review is an attempt to examine and discuss the physiological basis underlying exhaled NO measurements and the clinical evidence of the usefulness of this method in asthma and various other respiratory disorders. Expert commentary: Estimation of the NO parameters would aid in our understanding of the NO dynamics of the lung and thereby give more knowledge how to interpret the measured F_ENO value in clinical practice.

[Hepatopulmonary syndrome]

Hepatopulmonary syndrome (HPS) is defined by the association of portal hypertension, increased alveolar-arterial oxygen gradient and intrapulmonary vascular dilations. Pathophysiological mechanisms of hypoxemia are characterized by ventilation-perfusion mismatch, oxygen diffusion limitation between alveolus and the centre of the dilated capillary, and right-to-left shunting. An excess of vasodilator molecules (like nitric monoxide) and proangiogenic factors (like VEGF) play an important role in the occurrence of HPS. Symptoms of HPS are not specific and dominated by a progressive dyspnea in upright position. Pulse oximetry is a simple non-invasive screening test but only detect the most severe forms of HPS. Medical treatment is disappointing and only liver transplantation may lead to resolution of HPS. Survival following liver transplantation is promising when hypoxemia is not severely decreased.

Inflammatory bowel diseases, chronic liver diseases and the lung

This review is devoted to the distinct associations of inflammatory bowel diseases (IBD) and chronic liver disorders with chronic airway diseases, namely chronic obstructive pulmonary disease and bronchial asthma, and other chronic respiratory disorders in the adult population. While there is strong evidence for the association of chronic airway diseases with IBD, the data are much weaker for the interplay between lung and liver multimorbidities. The association of IBD, encompassing Crohn's disease and ulcerative colitis, with pulmonary disorders is underlined by their heterogeneous respiratory manifestations and impact on chronic airway diseases. The potential relationship between the two most prevalent liver-induced pulmonary vascular entities, i.e. portopulmonary hypertension and hepatopulmonary syndrome, and also between liver disease and other chronic respiratory diseases is also approached. Abnormal lung function tests in liver diseases are described and the role of increased serum bilirubin levels on chronic respiratory problems are considered.

[Pulmonary CO/NO transfer: physiological basis, technical aspects and clinical impact]

Diseases affecting the alveolar-capillary membrane or the capillary blood vessels can impair pulmonary gas exchanges and lung diffusion. The single-breath transfer factor of the lung for carbon monoxide (TL,CO) is the classical technique for measuring gas transfer from the alveolus to the pulmonary capillary blood. Pulmonary gas exchanges can also be explored by the transfer factor of the lung for nitric oxide (TL,NO). TL,NO represents a better index for the diffusing capacity of the alveolar-capillary membrane whereas TL,CO is more influenced by red blood cell resistance. Membrane diffusing capacity (DM) and pulmonary capillary blood volume (Vc) derivated from TL,CO and TL,NO by the Roughton-Forster equation can give additional insights into pulmonary pathologies. The clinical impact of the CO/NO transfer has still to be precised even if this measurement seems to provide an alternative way of investigating the alveolar membrane and the blood reacting with the gas.

Relevance of partitioning DLCO to detect pulmonary hypertension in systemic sclerosis

We investigated whether partitioning DLCO into membrane conductance for CO (DmCO) and pulmonary capillary blood volume (Vcap) was helpful in suspecting precapillary pulmonary (arterial) hypertension (P(A)H) in systemic sclerosis (SSc) patients with or without interstitial lung disease (ILD). We included 63 SSc patients with isolated PAH (n=6), isolated ILD (n=19), association of both (n=12) or without PAH and ILD (n=26). Partitioning of DLCO was performed by the combined DLNO/DLCO method. DLCO, DmCO and Vcap were equally reduced in patients with isolated PAH and patients with isolated ILD but Vcap/alveolar volume (VA) ratio was significantly lower in the isolated PAH group. In patients without ILD, DLCO, DmCO, Vcap and Vcap/VA ratio were reduced in patients with isolated PAH when compared to patients without PAH and both Vcap/VA and DLCO had the highest AUC to detect PAH. In patients with ILD, Vcap had the highest AUC and performed better than DLCO to detect PH in this subgroup. In conclusion, Vcap/VA was lower in PAH than in ILD in SSC whereas DLCO was not different. Vcap/VA ratio and DLCO had similar high performance to detect PAH in patients without ILD. Vcap had better AUC than DLCO, DmCO and FVC/DLCO ratio to detect PH in SSC patients with ILD. These results suggest that partitioning of DLCO might be of interest to detect P(A)H in SSC patients with or without ILD.

[COPD in dairy farmers: screening, characterization and constitution of a cohort. The BALISTIC study]

BACKGROUND

A pilot study from our group suggests that the prevalence of chronic obstructive pulmonary disease (COPD) among dairy farmers is higher than in the general population although dairy workers are less frequently smokers.

OBJECTIVES AND METHODS

The study presented here aims at (i) determining the prevalence of COPD in a large and representative population of dairy farmers; (ii) characterizing these patients in terms of smoking habits, dyspnoea, quality of life, lung function, bronchial exhaled nitric oxide, systemic inflammation, arterial stiffness and exercise capacity; (iii) comparing characteristics of dairy farmers' COPD with the characteristics of COPD in patients without any occupational exposure; (iv) identifying the etiological factors of COPD in dairy farmers; and (v) constituting a cohort of COPD patients and control subjects for further longitudinal studies. Two groups of COPD patients (dairy farmers or not) and two groups of controls subjects will be selected among a representative panel of 2000 dairy workers and 2000 subjects without any occupational exposure, all aged 40 to 75 years.

EXPECTED RESULTS

A better knowledge of the epidemiology and pathophysiology of COPD in dairy farmers should guide a specific strategy of prevention. The knowledge of the characteristics of COPD occurring in dairy farmers will help to define the therapeutic modalities that might be different compared with the therapeutic recommendations for COPD secondary to tobacco smoking.

Circulating nitric oxide products do not solely reflect nitric oxide release in cirrhosis and portal hypertension

BACKGROUND

Patients with cirrhosis often develop a systemic vasodilatation and a hyperdynamic circulation with activation of vasoconstrictor systems such as the renin-angiotensin-aldosterone system (RAAS), and vasopressin. Increased nitric oxide (NO) synthesis has been implicated in the development of this state of vasodilation and pulmonary dysfunction including increased exhaled NO concentrations. Circulating metabolites (NO(x)) may affect the systemic and pulmonary NO-generation. However, the relations of these abnormalities to the haemodynamic changes remain unclear.

AIMS

The aims of the present study were to measure changes in exhaled NO in relation to circulating NO(x), RAAS, and haemodynamics.

METHODS

Twenty patients (eight child class A and 12 class B patients) underwent a liver vein catheterization with determination of splanchnic and systemic haemodynamics. Circulating NO(x) and exhaled NO were determined in the supine and sitting positions and related to haemodynamics, RAAS and lung diffusing capacity (D(L)CO). Eight matched healthy individuals served as controls.

RESULTS

All patients with cirrhosis had portal hypertension. We found no significant difference in exhaled NO between patients and controls and no changes from the supine to the sitting position. Exhaled NO in the patients correlated significantly with plasma volume, heart rate and D(L)CO. NO(x) concentrations were not significantly increased in the patients. NO(x) correlated with portal pressure and haemodynamic indicators of vasodilatation, but not with exhaled NO concentrations.

CONCLUSION

In patients with moderate cirrhosis, exhaled NO is normal. Circulating NO(x) do not seem to reflect pulmonary and systemic NO release, but NO(x) seems to reflect systemic and splanchnic haemodynamic changes in cirrhosis.

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.

Gas exchanges and pulmonary vascular abnormalities at different stages of chronic liver disease

BACKGROUND

It is unclear whether and to which extent respiratory function abnormalities may complicate the earliest stages of chronic liver disease (CLD). Aim of this study was to compare pulmonary capillary volumes and gas exchange efficiency of CLD patients with and without cirrhosis.

METHODS

Sixty-seven participants (mean age 56.5 years; women 22.4%) were divided into three groups (matched by age, sex, smoking) according to the baseline CLD stage as follows: (a) healthy controls (Group A, n=20); (b) non-cirrhotic CLD patients (Group B; n=23); (c) cirrhotic CLD patients (Group C; n=24). All participants underwent clinical assessment, respiratory function tests, gas exchange estimation by the alveolar diffusion of carbon monoxide (TLCO) measurement and 6-min walking test. Groups were compared by chi-square and one-way anova tests.

RESULTS

Chronic liver disease patients had significantly lower levels of TLCO (Group B=17.7 ml/min mmHg, and Group C=14.2 ml/min mmHg) compared with healthy controls (Group A=24.4 ml/min mmHg). Consistent results were obtained when analyses were performed using TLCO expressed as percentage of the predicted value. TLCO adjusted for the alveolar volume was lower in cirrhotic patients compared with both controls and non-cirrhotic CLD patients (P<0.001 and P=0.035 respectively). Group C participants presented blood gas parameters tending to a compensated chronic respiratory alkalosis status compared with the other groups.

CONCLUSIONS

Pulmonary microvascular and gas exchange modifications are present at early stages of CLD. Future studies should be focused at evaluating the pathophysiological mechanisms underlying this relationship.

Pulmonary dysfunction and hepatopulmonary syndrome in cirrhosis and portal hypertension

BACKGROUND

Pulmonary dysfunction including the hepatopulmonary syndrome (HPS) is an important complication to cirrhosis and portal hypertension. However, the precise relation to liver dysfunction and the prevalence of HPS are unclear.

AIMS

We therefore aimed to assess (i) the prevalence of HPS in consecutive alcoholic cirrhotic patients, (ii) the degree of pulmonary dysfunction in relation to liver function and (iii) the response of a 100% oxygen test on cardiopulmonary and peripheral oxygenation.

METHODS

Fifty patients with cirrhosis and 12 matched healthy controls were entered in this study. All underwent haemodynamic and pulmonary investigations [lung diffusing capacity for carbon monoxide (DLCO), contrast-enhanced echocardiography and detection of extrapulmonary shunt fraction]. A 100% oxygen test was performed with the assessment of arterial oxygen tension (PaO(2)), the alveolar-arterial oxygen gradient (AaPO(2)) and peripheral transcutaneous oxygen tension (tcPO(2)).

RESULTS

The prevalence of HPS was 10%. PaO(2) and DLCO were reduced in 32 and 72% and AaPO(2), was increased in 60% of the patients respectively. DLCO correlated with indicators of liver dysfunction (galactose elimination capacity, P<0.01, indocyanine green clearance, P<0.001), portal hypertension (post-sinusoidal resistance, P<0.01) and central hypovolaemia (central and arterial blood volume, P<0.01). After 100% oxygen inhalation, the changes in PaO(2), AaPO(2), tcPO(2) and heart rate were abnormal in the patients compared with controls (P<0.02).

CONCLUSIONS

Pulmonary dysfunction in alcoholic cirrhosis is common and relates to different aspects of liver dysfunction, whereas the prevalence of HPS is low. The haemodynamic response to oxygen inhalation is clearly impaired and HPS and pulmonary dysfunction seem to be caused by different pathophysiological mechanisms.