Hepatopulmonary syndrome

Introduction to hepatopulmonary syndrome Hepatopulmonary syndrome (HPS) is hypoxemia caused by abnormal pulmonary vasodilation and arterial oxygenation caused by various acute and chronic liver diseases. Because hepatopulmonary syndrome is a triad of pulmonary vasodilation and insufficient arterial oxygenation caused by primary liver disease. basic knowledge The proportion of patients: the incidence of this disease in patients with liver disease is about 0.02%-0.1% Susceptible population: more common in severe liver disease Mode of infection: non-infectious Complications: spider mites, ascites

Causes of hepatopulmonary syndrome

Cause:

The cause of liver disease caused by hypoxemia: all kinds of acute and chronic liver diseases can be associated with pulmonary vascular abnormalities and arterial hypoxemia, the most important is liver cirrhosis caused by chronic liver disease, especially cryptogenic cirrhosis, alcohol Liver cirrhosis, hepatitis cirrhosis and primary biliary cirrhosis, also seen in chronic hepatitis, acute severe hepatitis, cholestasis, sputum-antitrypsin deficiency, Wilson's disease, tyrosinemia, and non-cirrhotic portal vein High pressure such as idiopathic portal hypertension, schistosomiasis cirrhosis, etc., extrahepatic portal vein obstruction can also be complicated by arterial hypoxemia. Observation of these patients suggests that portal hypertension may be the main pathogenesis of hepatopulmonary syndrome, Binay et al. The study found that hepatopulmonary syndrome is most likely to occur with progressive hepatic failure with high power circulation, and it was not found to be associated with the severity of cirrhosis.

Pathophysiology

The essence of hepatopulmonary syndrome is hypoxemia caused by pulmonary vasodilation and abnormal arterial oxygenation in liver disease. Arterial hypoxemia is due to insufficient red blood cells in the blood flowing through the lungs. Oxygenation or part of the blood does not flow through the alveoli to cause oxygenation. Since HPS has ruled out primary cardiopulmonary disease, the abnormal pathways that red blood cells may pass are: through the pleural and hilar bronchial vessels without reaching Alveolar; in the mediastinum, blood flow directly into the pulmonary veins due to the higher pressure of the portal system, thereby bypassing the lung circulation; through the dilated alveolar capillaries or pulmonary arteriovenous fistulas directly into the pulmonary veins, alveolar telangiectasia for hypoxemia The formation may be more important. The existing research data show that the occurrence of hepatopulmonary syndrome is at least related to systemic hyperdynamic state, portal hypertension, hepatic encephalopathy, hepatorenal syndrome and pulmonary hypertension, so the cause is also systemic metabolism. And caused by hemodynamic disorders, but also involved in the formation of systemic metabolism and hemodynamic disorders, is important Pathophysiological significance.

(1) The basic pathological change of hepatopulmonary syndrome is pulmonary vasodilation, which is expressed as:

1 a large amount of pre-capillary expansion.

2 The formation and opening of the arteriovenous traffic branch at the base of the lung.

3 pleural "spider sputum" formed, previously telangiectasia.

In autopsy, it has been found that the basic pathological changes in the lungs of patients with chronic liver disease such as cirrhosis are extensive in the lungs.

Hepatopulmonary syndrome prevention

Active and effective treatment of primary liver disease is the basis for the prevention of this disease.

Hepatic and pulmonary syndrome complications Complications

Patients may appear: liver palm, hepatosplenomegaly, spider mites, ascites; due to hypoxemia, the patient changed from supine to standing with palpitation, chest tightness, shortness of breath.

Hepatic and pulmonary syndrome symptoms Common symptoms Jaundice dyspnea hypoxemia Clubbing (toe) Purpura liver palmar ascites spider hernia short supine breathing

Because hepatopulmonary syndrome is a triad of pulmonary vasodilation and insufficient arterial oxygenation caused by primary liver disease, its clinical manifestations are mainly liver disease and lung lesions.

1. Clinical manifestations of primary liver disease Hepatic and pulmonary syndrome can occur in various liver diseases, but chronic liver disease is the most common, especially cirrhosis caused by various causes such as cryptogenic cirrhosis, alcoholic cirrhosis, hepatitis cirrhosis , after liver cirrhosis and biliary cirrhosis, most patients (about 80%) see the clinical manifestations of various liver diseases, and this fashion lacks respiratory symptoms, the clinical manifestations of various liver diseases due to the cause, course of disease and The degree of hepatocyte dysfunction and complications are different, and the most common clinical manifestations include liver palm, spider mites, jaundice, hepatosplenomegaly, ascites, gastrointestinal bleeding, liver dysfunction, etc., but with liver and lung There is no significant correlation between the syndromes. Some patients with stable liver disease can also have clinical manifestations of progressive pulmonary function decline. There are data showing that in patients with chronic liver disease, spider mites appear in patients with cirrhosis, suggesting that there may be pulmonary vascular beds. Abnormal changes, and even some people think that with spider corpus callosum, systemic and pulmonary vasodilation is obvious, gas exchange disorders are serious, suggesting that it may be pulmonary vasodilation The epidermis mark.

2. Clinical manifestations of pulmonary dysfunction Because patients with this disease have no primary cardiopulmonary disease, most (80% to 90%) patients gradually develop respiratory manifestations on the basis of various liver diseases, such as cyanosis, difficulty breathing, and symptoms. Finger (toe), orthostatic hypoxia, platypnea, etc. Among them, progressive dyspnea is the most common pulmonary symptom of hepatopulmonary syndrome. Binay et al believe that cyanosis is the only reliable clinical sign, supine breathing, erect Sexual hypoxia is the most characteristic manifestation of intrinsic cerebral examination. There is no obvious positive sign in lung examination. A small number of patients (about 16% to 20%) can be treated with exercise dyspnea in the absence of clinical manifestations of various liver diseases. Clinical attention should be paid to prevent misdiagnosis. Domestic Gaozhi et al reported that two patients with hepatopulmonary syndrome were treated with cyanosis, palpitation after activity, and shortness of breath. The clinical manifestations of cirrhosis (such as liver palm and spider) were also found. Hemorrhoids, hepatosplenomegaly, ascites), is conducive to the diagnosis of this disease, such as liver disease patients with other lung diseases (such as chronic bronchitis, emphysema and pneumonia, pleural effusion, etc.) can coexist with hepatopulmonary syndrome, then Can be Obvious respiratory symptoms should be noted. There are data studies showing that patients with hepatopulmonary syndrome need an average of 2 to 7 years from the initial dyspnea to a definitive diagnosis, and about 18% of patients have already appeared when the diagnosis of liver disease is clear. Difficulty breathing.

(1) Orthostatic hypoxia (orthodeoxidation): PaO2 decreased by >10% when the patient changed from supine position to standing position.

(2) platypnea: palpitnea, chest tightness, shortness of breath, and symptoms of improvement in patients with supine position. According to Krowka, about 80% to 90% of hepatopulmonary syndrome The above two manifestations are due to the fact that the pulmonary vasodilation of the patients with hepatopulmonary syndrome is mainly distributed in the middle and lower lung fields. When the patient is from the supine position to the standing position, the blood flow in the middle and lower lungs increases due to the gravity, which is aggravated. Caused by hypoxemia, although the above two performances are not specific to hepatopulmonary syndrome, it suggests that patients have obvious abnormalities in the pulmonary vasculature. For example, patients with various liver diseases have these two manifestations, and further examination should be performed to confirm .

Hepatic and pulmonary syndrome examination

Blood gas analysis: hypoxemia is the basic pathophysiological change of hepatopulmonary syndrome, so blood gas analysis is necessary for the diagnosis of this disease. In patients with liver disease without primary cardiopulmonary disease, if there is obvious hypoxemia, it indicates the disease. The diagnosis is mainly as follows: arterial oxygen partial pressure (PaO2) <9.33 kPa (70 mmHg), blood oxygen saturation (SaO2) <94%, alveolar-arterial blood oxygen gradient (>4.53 kPa or 34 mmHg), patient Respiratory alkalosis due to hypoxia: such as decreased arterial blood carbon dioxide partial pressure (PaO2), elevated pH, is currently considered a prerequisite for PaO2 decline, but some people think that alveolar-arterial blood oxygen gradient may be more sensitive .

1. Pulmonary function measurement : can measure vital capacity, maximum ventilation, functional residual capacity, total lung volume, respiratory reserve volume, R/T, 1s forced expiratory volume, lung carbon monoxide diffusion, etc., without obvious chest, ascites Although the lung volume and expiratory volume of patients with hepatopulmonary syndrome can be basically normal, there is still a significant change in the amount of diffusion. Even if the hemoglobin is corrected, it is still abnormal. Generally, the liver disease develops to the advanced stage and has pulmonary dysfunction, which can be expressed as lung Decreased air volume, increased airway resistance, impaired gas diffusion function, etc., should be checked when pulmonary function tests find an increase in expiratory resistance; such as sputum-antitrypsin and phenotype to distinguish between cirrhosis and emphysema presence.

2. X-ray examination: the general patient's chest radiograph may have no obvious abnormality, and some patients may have double sub-lung field interstitial shadow enhancement, mainly as follows:

(1) The interstitial texture of the lungs is increased and enhanced.

(2) diffuse small miliary shadows dominated by the following lung fields.

(3) pulmonary artery expansion.

Some people think that the basal nodules or reticular nodules are the manifestations of vasodilation in the lungs, but this damage is difficult to find in autopsy. The typical manifestation of X-ray examination is 1.3 to 1.6 mm at the base of the lung. Moderately sized nodular or reticular nodular shadows, 5% to 13.8% in patients with chronic liver disease, and 46% to 100% in patients with HPS, but this performance is not considered It is specific and can also be present in pulmonary fibrosis or granulomatous diseases, which can be distinguished by pulmonary function tests, angiography or CT examination.

3. CT: can show distal vasodilation, and there are a large number of abnormal peripheral branches, and can exclude other causes of hypoxemia, such as emphysema or pulmonary fibrosis, but the above changes are not specific, existing people It is suggested that the reconstruction of pulmonary vascular images by three-dimensional reconstruction spiral CT may be a hot spot in the future. It has the same accuracy as selective pulmonary angiography in distinguishing the visible arteriovenous anomalies.

4. Contrast-enhanced two-dimensional echocardiography : Two-dimensional echocardiography with contrast-enhanced contrast is the preferred method for non-invasive examination of vascular dilatation in the lung. This method was first applied to patients with cirrhosis by Hind and Wong et al. Detection of pulmonary vasodilation, the principle is: stirring physiological saline and indocyanine green dye can produce 60 ~ 90m microbubbles, after injection from the peripheral vein microbubbles from the right heart through the dilated pulmonary vessels deposited in the left atrium, under normal circumstances The bubble is inhaled into the alveoli when it passes through the capillary bed (8 to 15 m in diameter) or is dissolved in the blood and cannot appear in the left atrium. This method relies on the time when the microbubble appears in the left atrium to distinguish between intracardiac shunt and intrapulmonary. Diversion, right-to-left intracardiac shunt can appear microbubbles in the left atrium immediately after microbubbles appear in the right atrium. If there is anterior telangiectasia in the lung, microbubbles appear after 4 to 6 cardiac cycles in the right atrium. In the left atrium, the method is to give the patient an intravenous injection of indocyanine green. When the microbubbles appear in the right atrium, a two-dimensional echocardiogram can produce an instantaneous echo or a cloud-like shadow in the right atrium. The above changes in the ultrasound changes in the left atrium after 3 to 6 cardiac cycles, suggesting that there is pulmonary vasodilation, and the negative result can basically rule out the diagnosis of hepatopulmonary syndrome. This method is more than arterial oxygen partial pressure and lung scan. Sensitive is the most suitable screening method at present, but the shortcoming is that it is impossible to determine the specific part of the diseased blood vessel, and the degree of shunt can not be evaluated. Recently, it is easier to detect the microbubble by transesophageal two-dimensional echocardiography, and it can be determined The distribution in the bronchi, which is used to locate the vasodilation in the lung, occurs in the upper or lower lung.

5. Pulmonary angiography: It is a traumatic diagnostic technique. Although it has certain risks, it is still considered as the gold standard for determining pulmonary vascular changes and localization. It can not only distinguish hepatopulmonary syndrome hypoxemia and pulmonary embolism. Hypoxemia can also provide a basis for the choice of surgical treatment for patients with hepatopulmonary syndrome. If the pulmonary vascular injury is relatively isolated, selective pulmonary embolism or lobectomy may be considered. The pulmonary vascular disease may have the following three types. Performance: Type I spider-like diffuse dilatation, more common in the early stage of hepatopulmonary syndrome, this stage has a good response to pure oxygen; type II cavernous artery dilatation, mainly located in the bottom of the lung, more common in the mid-stage of hepatopulmonary syndrome, this period The reaction to pure oxygen is limited; type III direct pulmonary movement, venous traffic, can be seen at the level of the hilar or at the base of the lung, with isolated scorpion or squamous shadows, similar to arteriovenous malformations, clinically severe hypoxia, cyanosis Obviously, there is no response to pure oxygen absorption. Domestic Gao Zhi et al believe that the sensitivity of pulmonary angiography is not as good as that of contrast-enhanced two-dimensional echocardiography and the following lung scans. Some people will also have pulmonary angiography. The types are summarized as follows: type I diffuse pre-capillary dilatation, angiography shows a spider-like or spongy image (inhalation of 100% oxygen can cause PaO2 to rise), type II intermittent local arterial malformation or traffic branch formation, angiography It is shown as an isolated sacral or lumpy image (inhalation of 100% oxygen has little effect on PaO2). The disadvantage is that pulmonary angiography does not show small peripheral arteriovenous malformations and can produce false negative results.

6.99m-labeled giant coagulation albumin lung scan (99mTc-MAA) : The principle of this method is the same as that of microbubble contrast enhanced two-dimensional echocardiography, which uses macrogel albumin with a particle diameter greater than 20m, under normal conditions Can not pass through the capillary network, all lung scanning substances are concentrated in the vasculature of the lungs, but pulmonary vasodilation and pulmonary arteriovenous shunt can pass through and deposit in the liver, brain and kidney tissue, using this method Radionuclide scanning can semi-quantitatively detect pulmonary vasodilation and intrapulmonary shunt, and can track changes in the condition. Abrams et al believe that HPS can evaluate hypoxia in patients with cirrhosis with HPS with primary lung disease. The extent of the impact of blood helps determine whether liver transplantation is a treatment, because hypoxemia caused by severe primary lung disease is a contraindication to liver transplantation, but negative results do not completely rule out HPS.

7. Intravenous catheter manometry: pulmonary vein pressure gradient (HVPG), mean pulmonary artery pressure (PAP) and pulmonary capillary incarceration pressure (PCWP) can be measured by hepatic and pulmonary venous catheterization to understand the presence or absence of pulmonary hypertension, Binay A study of 3 patients with hepatopulmonary syndrome showed pulmonary vascular resistance (PAR), and PCWP values were lower than those with negative echocardiographic echocardiography.

8. Pathological changes: It is the most reliable indicator for the diagnosis of HPS. The basic pathological changes are pulmonary vasodilation, which is characterized by diffuse massive anterior telangiectasia or discontinuous arteriovenous traffic branch formation, fulminant hepatic failure and end-stage chronic liver disease. Patients have demonstrated pulmonary vasodilation, one type of structural change is the anterior telangiectasia adjacent to the normal lung gas exchange unit, and the other is a large arteriovenous branch away from the lung gas exchange unit. The vascular cast can display Abnormal blood vessels and their relationship and pathways can only distinguish large shunts and hemangiomas from the large examinations and tissue light microscopy. It is easier to find anatomically abnormal pathways (including changes in small blood vessels), applications such as Fritts The radionuclide Kr85 is dissolved in a water-soluble dye intravenously, and the ratio between the arterial blood kr85 and the dye can be analyzed to estimate the shunt. The methacrylate can be used for more detailed vascular casting research.

9. Other examinations : blood biochemical tests often show liver dysfunction, but the degree is not proportional to the development of hepatopulmonary syndrome, liver function tests, protein classification, virological markers and other liver disease examination items, see relevant content, and other feasible Gastroscope, etc. in order to find the presence of portal hypertension.

Diagnosis and differential diagnosis of hepatic and pulmonary syndrome

Diagnostic criteria

At present, there is no uniform standard for the diagnosis of HPS. The diagnosis should be based on clinical manifestations and the imaging evidence of pulmonary vasodilation should be diagnosed.

1.Rodriguer-Roisin is equal to the diagnostic criteria for HPS in 1992.

(1) There is chronic liver disease, and there is no serious liver dysfunction.

(2) No cardiopulmonary disease, chest X-ray examination is normal or accompanied by nodular shadows on the base of the lung.

(3) Abnormal lung gas exchange, increased alveolar-arterial oxygen gradient (20kPa), may have hypoxemia.

(4) Contrast-enhanced two-dimensional echocardiography and/or pulmonary perfusion scan. Pulmonary angiography demonstrates the presence of pulmonary vasodilation and/or intrapulmonary vascular short circuit, and the clinical manifestations such as orthostatic hypoxia and shortness of breath are important reference indicators. .

2. Chang SW is equal to the diagnostic criteria for the disease in 1996.

(1) Liver dysfunction.

(2) Hypoxemia, alveolar gas-arterial oxygen partial pressure difference [P(Aa)O2]2.67kPa or orthostatic hypoxia in resting position breathing air.

(3) Vascular dilatation in the lungs.

3. Krowka is equal to 1997. When patients have portal hypertension, spider mites and clubbing, they strongly suggest the diagnosis of this disease. Relevant examinations are needed to confirm the diagnosis. The criteria for diagnosis are:

(1) 99mTc-MAA scan, contrast-enhanced two-dimensional echocardiography, pulmonary angiography, etc. confirmed the presence of intrapulmonary telangiectasia.

(2) Chronic liver disease and hypoxemia PaO2 < 9.3 kPa (70 mmHg).

Domestic Gaozhi is equal to 1998. The diagnosis of this disease is based on the patient's hepatosplenomegaly, ascites, liver palm, spider mites, exertional dyspnea, supine breathing and orthostatic hypoxia. The chest radiograph shows the interstitial of the lung base. And vascular texture increased, can be patchy or nodular, reticular nodular shadow, CT shows basal pulmonary vasodilation, pulmonary vascular branch increased, blood gas analysis does not necessarily have severe hypoxemia, but alveolar-arterial Increased oxygen gradient 20 kPa, 82% of pulmonary function tests have a comprehensive analysis of diffusion disorders, in addition to the need for cross-flow examination, such as 99mTc-MAA scan, contrast-enhanced two-dimensional echocardiography, pulmonary angiography, etc. However, the latter is not as sensitive as the former two because small blood vessel dilatation in the lung does not necessarily manifest in angiography.

Binay et al believe that patients with cirrhosis do not have cyanosis, clubbing and spider mites, arterial blood gas analysis, PaO2 and lung function tests are normal, and patients with positive echocardiographic echocardiography have developed pulmonary vasodilation. For the "subclinical" hepatopulmonary syndrome, it needs to be given clinical attention.

Differential diagnosis

First of all, it is necessary to exclude the original cardiopulmonary diseases of patients with liver diseases, such as chronic obstructive emphysema, pulmonary infection, interstitial pneumonia, silicosis, etc., and need to exclude cirrhosis with pulmonary hypertension, pleural effusion, secondary infection, interstitial Pulmonary edema, atelectasis, hyperventilation syndrome, etc., patients with hepatopulmonary syndrome can also concurrently with the above-mentioned diseases, but also need careful and meticulous examination to facilitate identification.

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