hepatopulmonary syndrome
Introduction
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. It is essentially primary liver disease, pulmonary vasodilation and arterial oxygenation. Insufficient triad. Under normal circumstances, moderate to severe hypoxemia (PaO2 <9.33 kPa) is included in the category of hepatopulmonary syndrome, which is caused by the abnormal increase of vasodilator substances in the liver caused by chronic liver disease, resulting in pulmonary arteriovenous shunt, Pathological and physiological changes such as ventilatory/blood flow imbalance, portal-pulmonary venous shunt, and primary pulmonary hypertension. basic knowledge The proportion of illness: 0.005% Susceptible people: no specific population Mode of infection: non-infectious Complications: spider mites, ascites
Cause
Causes of hepatopulmonary syndrome
(1) Causes of the disease
Portal hypertension (65%)
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 pathogenic factor of hepatopulmonary syndrome.
Liver failure (25%)
In 2000, Binay et al found that hepatopulmonary syndrome was most likely to occur with progressive hepatic failure with high dynamic circulation, and it was not found to be associated with the severity of cirrhosis.
(two) pathogenesis
1. Pathophysiology The essence of hepatopulmonary syndrome is hypoxemia caused by pulmonary vasodilation and abnormal arterial oxygenation in liver disease. Arterial hypoxemia is due to blood in the blood flowing through the lungs. Erythrocytes do not get sufficient oxygenation or part of the blood does not flow through the alveoli for oxygenation. Since HPS has ruled out primary cardiopulmonary disease, the abnormal pathways that red blood cells may pass through are: pleural and hilar bronchus The blood vessels do not reach the alveoli; 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 The formation of hypoxemia 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 it occurs. The cause is also caused by systemic metabolism and hemodynamic disorders, and is also involved in the formation of systemic metabolism and hemodynamic disorders. It has 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 is found that the basic pathological changes in the lungs of patients with chronic liver disease such as cirrhosis are extensive intrapulmonary vasodilation and arteriovenous communication. Some of the pathological changes and pleural vasodilation or subpleural spiders are found by vascular shaping. In the formation of sputum, Professor Gu Changhai summarized these pathological changes in 1997 as: the uneven distribution of the internal acinar artery of the lung; the thin blood vessels with a diameter of 60-80 m can be seen in the lower lobe of the lung; the capillaries in front of the alveolar gas The horizontal pulmonary vascular bed is extensively dilated; the pulmonary artery branches and pulmonary capillaries are significantly dilated, up to 160 m in diameter, and electron microscopy shows that the pulmonary capillaries and pulmonary arterioles are thickened and the basal layer of the venules is thickened.
(2) Factors affecting vascular dilatation in the lung: The mechanism of vasodilation in the lung has not yet been fully elucidated, and its possible influencing factors are:
1 increased vasodilator activity: a variety of acute and chronic liver disease hepatocyte failure, metabolic disorders, especially the reduction of vasoactive substances, and can directly enter the systemic circulation through abnormal anastomotic collateral vessels, resulting in systemic hemodynamics Disorder, blood circulation, vasodilator content increased, like visceral congestion in patients with portal hypertension, pulmonary blood vessels caused by pulmonary blood vessels, pulmonary congestion, vasodilating substances such as: glucagon, prostaglandin, vasoactive Enteric peptide, nitric oxide, kallikrein, bradykinin and its endotoxin.
2 decreased vasoconstrictor or decreased sensitivity of the intrapulmonary vascular bed to endogenous vasoconstrictors: such as norepinephrine, endothelin, atrial natriuretic peptide, vasopressin, serotonin, tyrosine, etc. The content of the substance is not absolutely reduced, it may be that the sensitivity of its action is reduced, resulting in the opening of the non-functional anterior communicating branch of the capillaries, and the normal hypoxic pulmonary vasoconstriction function, which is only normal. %.
3 neurological factors: sympathetic tone in patients with cirrhosis, but the formation of portal hypertension is impaired in sympathetic function in the body, may play an important role, portal hypertension animals often show abnormal compression reaction, blood vessels to the norepinephrine The sensitivity of the hormone is reduced, the cardiac output is increased, the blood vessel volume in the lung is also expanded, and the high blood flow state in the lung is also a manifestation of the whole body high dynamic state.
4 Intrapulmonary vascular reactivity to hypoxia is reduced: In recent years, two patients with cirrhosis above the spider mites have been found by inert gas diffusion test, which not only shows impaired liver function, but also reduces systemic vascular and pulmonary vascular resistance. The reactivity to hypoxia is also reduced, and the blood vessels in the lungs are dilated. However, although pulmonary angiography has been used, although the vasodilation of the arterial tip has been found, the response to oxygen is almost normal, and this view is not supported.
5 angiogenesis or dysplasia in the lung may also be one of the factors in the formation of hepatopulmonary syndrome.
So far, the mechanism of pulmonary vasodilation caused by hepatopulmonary syndrome is unclear, but long-term effects of vasoactive substances in the lung can cause intracellular cyclic adenosine monophosphate (cAMP) and/or cyclic guanosine monophosphate (cGMP). Significantly elevated, leading to hypoxia-induced pulmonary vasomotor dysfunction, pulmonary artery dilatation, may be an important cause of the disease, may also be the pulmonary manifestations of systemic hyperkinetic circulation, due to significant expansion of pulmonary capillaries and anterior capillaries Some blood in contact with the alveoli around the capillaries can still be exchanged with gas, but the blood in the central part is insufficiently exchanged due to the increased distance between the alveolar and the alveolar, resulting in insufficient oxygenation of the arteries and a series of hypoxia. Blood performance.
2. Pathogenesis So far, the pathogenesis of this disease has not been elucidated. In view of the above pathophysiological changes and current research, the pathogenesis of this disease may be inadequate ventilation, diffusion disorder, ventilatory/blood flow imbalance, and decreased oxyhemoglobin affinity. The result of a combination of factors or factors.
(1) Insufficient ventilation: Under normal circumstances, insufficient ventilation due to various reasons, insufficient oxygen inhalation into the alveoli, reduced blood oxygen exchange, can cause hypoxemia, such as chronic bronchitis, tracheal foreign body, atelectasis and breathing Muscle paralysis, etc., and in chronic liver disease, whether there is insufficient ventilation in patients with cirrhosis is still controversial.
In 1982, Fujiwara studied the lung function of 22 patients with decompensated cirrhosis. It was found that the patient's vital capacity (VC), functional residual capacity (FRC) and respiratory reserve volume (EVR) were significantly reduced, while R/T was slightly elevated. There is no change in forced expiratory volume (FEV1) of 1s. It is believed that pulmonary interstitial edema in patients with cirrhosis causes mechanical compression of lung tissue. Insufficient ventilation function is the main cause of impaired lung function. Later, Edison et al. The lung function of patients with decompensated cirrhosis was studied. It was found that the vital capacity, maximum ventilation (MVV), functional residual capacity, total lung volume, and R/T were significantly lower. It is considered that patients with cirrhosis have obvious obstructiveness. And the lack of restrictive ventilation is due to increased intra-abdominal pressure, increased diaphragmatic pressure, decreased chest volume, increased pressure, and other compression of lung tissue and atelectasis in patients with ascites. The decrease in forced expiratory volume in 1s is due to the lungs. Quality edema and vasodilatation oppress the small trachea, early closure of exhalation, in theory, these factors can lead to inadequate ventilation, is one of the factors causing this disease, which is also given to patients with cirrhosis with pleural effusion Taking pleural effusion, the arterial partial pressure of oxygen decreased significantly after recovery of atelectasis, and the decrease of CO2 partial pressure confirmed that cirrhosis is accompanied by pleural and ascites, secondary infection of lung, pulmonary edema and patients with circulatory diseases. Hypoxemia can be caused by a marked deficiency in lung tissue ventilation.
On the contrary, some people think that hypoxia is not caused by insufficient ventilation. This is because patients with cirrhosis show a decrease in arterial oxygen partial pressure without high CO2, which may also be due to hypoxemia. Patients with hyperventilation can partially compensate for the arterial blood CO2 partial pressure not only does not increase, but PaCO2 decline, and even respiratory alkalosis, not only that, in some patients with liver cirrhosis without liver decompensation may also be associated with arteries Hypoxemia, and even some people found that cirrhosis patients with lung function tests are normal, therefore, most scholars believe that inadequate ventilation is not the main cause of hypoxemia in patients with cirrhosis.
(2) Dispersion disorder: The application of inert gas exclusion technique in patients with hepatopulmonary syndrome does prove that there is a disorder in the diffusion of oxygen, which is determined by pulmonary vasodilation as determined by pulmonary vasodilation. It also shows that there are tiny spider-like veins in the lungs to the obvious spongy diffuse vasodilation. Due to the significant expansion of the pulmonary capillaries and anterior capillaries, the diffusion distance between the blood flow and the alveoli in the central part of the blood vessels is increased, which prevents the gas in the alveoli from entering the lungs. Capillaries, which affect gas exchange, have been found to show that hypoxemia in patients with cirrhosis often occurs or worsens during exercise. It is believed that patients have diffuse or restricted O2 in the lungs. Agusti et al studied the movement of patients with cirrhosis. Pulmonary hemodynamics and gas exchange, found that the patient's PaO2 decreased significantly, while PaCO2 only mildly decreased, it is believed that this blood gas change can be explained by extrapulmonary factors. In fact, patients with cirrhosis do have the effect of O2 diffusion. Factors, but still not enough to explain the obvious hypoxemia, although patients with hepatopulmonary syndrome have arterial vasodilatation, The arterial oxygen partial pressure can be decreased when inhaling normal air, but the arterial oxygen partial pressure can be significantly increased when inhaled with pure oxygen, which further proves that although the diffusion disorder does exist, it must be established in the formation of this disease. The role, but not the important role.
(3) Ventilation/blood flow imbalance: Gas exchange is the most important biological function of lung tissue. This gas exchange must be fully completed under the appropriate ventilation/blood flow ratio. Normal condition (normal adult resting state) Under physiological conditions, the most appropriate ventilation/blood flow ratio is 0.8, and the ratio change caused by any cause can affect gas exchange, hypoxemia, and the cause of ventilatory/blood flow imbalance in patients with hepatopulmonary syndrome. It is pulmonary vasodilation and arteriovenous shunt.
1 Intrapulmonary vasodilatation: The vasodilation of the lung has been pathological, and angiography confirms that due to the expansion of the blood vessels in the lung, not only the gas diffusion disorder is caused, but also because the oxygen molecules in the air cannot diffuse to the center of the expanded blood vessel for gas exchange. The ratio of ventilation/blood flow decreases, and the partial pressure of pulmonary blood oxygen decreases. This decrease in the ratio of ventilation/blood flow combined with the increase in reactive cardiac output shortens the blood flow time through the capillary network, inadequate oxygenation, and excessive ventilation. Can partially improve the patient's PaO2, thus increasing the oxygen partial pressure in the alveoli, oxygen molecules can partially reach the center of the dilated blood vessels, so that the arterial oxygen partial pressure rises, so some people call this phenomenon a diffusion-perfusion disorder or intrapulmonary movement - Venous functional shunt, but not true intrapulmonary shunt, Krowka observed a group of patients with hepatopulmonary syndrome, 88% of the upright hypoxia, thought to be due to gravity, this vasodilation caused by increased blood flow mainly occurred in In the middle and lower lung areas, hypoxemia is more pronounced in the upright position.
2 arteriovenous shunt: cirrhosis can be complicated by pulmonary arteriovenous fistula and pleural spider mites, can make pulmonary blood flow without gas exchange, directly into the pulmonary veins, resulting in patients with significant hypoxemia, This hypoxemia can not be corrected by oxygen inhalation. It is a true intrapulmonary shunt. It has been confirmed by lung histopathology, angiography, two-dimensional contrast echocardiography, etc. It is currently believed that the application of pulmonary vascular cast is still To determine the most direct evidence of arteriovenous shunt, the pulmonary arteriovenous fistula was initially injected by Rydell and Hottbauer for the first time in the right pulmonary vasculature of a 11-year-old liver and lung syndrome in a patient with a wide range of motions. Intravenous traffic, there are many reports from domestic and foreign scholars. This is because the arteriovenous traffic branch is the same as the collateral circulation of the door. It is originally present and is closed under normal conditions, but under pathological conditions, As a result of reopening due to many factors such as nerves and body fluids, this intrapulmonary arteriovenous shunt is the main cause of insufficient gas exchange caused by abnormal ventilation/blood flow ratio. The pleural spider mites have a small amount of portal-pulmonary venous shunts, although they can also cause arteriovenous shunt, but they are not enough to cause obvious hypoxemia. In addition, many studies in recent years have found that some patients with cirrhosis still have a small amount of portal-pulmonary venous shunt. The blood flow does not directly enter the systemic circulation through alveolar gas exchange, and may also cause abnormal ventilation/blood flow ratio, resulting in insufficient gas exchange. Because this shunt is generally small, it is not enough to produce more severe hypoxemia, so it is not important. factor.
3 airway closure: In 1971, Ruff et al demonstrated that the closed volume (CV) and total closed air volume (CC) of patients with cirrhosis increased significantly, and the gas trapped in the lower lung field increased, resulting in a very low ventilation/blood flow rate. It is thought that it is caused by airway closure and reduced ventilation. In 1984, Furukawa et al measured 105 patients with cirrhosis and found no abnormalities in lung function, but most patients had abnormal flow-volume, and the volume of closed air increased significantly, suggesting airway. Closing early, the proportion of ventilation / blood flow decreased, may also be an important cause of hypoxemia.
4 oxygen and hemoglobin affinity decreased: a group of reports found that 15 patients with cirrhosis (mostly alcoholic cirrhosis) patients with mild systemic vascular or pulmonary vasodilation, PaO2 normal, mild hypocapnia, oxyhemoglobin dissociation The curve is slightly shifted to the right, the carbon monoxide diffusion is normal, and the mild ventilation/blood flow ratio is imbalanced, indicating that the patient's dissociation curve of oxygen is shifted to the right due to the decrease in affinity of hemoglobin and oxygen, possibly due to glycerol 2,3-diphosphate in red blood cells. Increased in ester concentration, but not an important factor in the development of hypoxemia.
In summary, there are many factors that cause hypoxemia, but it is difficult to fully explain the pathogenesis of this disease. Because the basic pathological changes of patients are open blood vessels in the lungs and open to the arteriovenous traffic, combined with recent years. The results of the study suggest that the diffuse disorder of alveolar and pulmonary capillary oxygen and the imbalance of ventilation/blood flow may exist at the same time, which is the main cause of hypoxemia in this disease. Other factors may aggravate hypoxia, which is a secondary factor. Therefore, it may be the result of the combination of the above factors.
Prevention
Hepatopulmonary syndrome prevention
Due to various urgency, chronic liver disease can be associated with pulmonary vascular abnormalities and arterial hypoxemia can cause hepatopulmonary syndrome, so active and effective treatment of primary liver disease is the basis for the prevention of this disease.
Complication
Hepatopulmonary 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.
Symptom
Symptoms of hepatopulmonary syndrome Common symptoms Astragalus, ascites, spider, sputum, sputum, supine, respiratory, liver, palm and lung, liver qi, lung dyspnea, clubbing (toe)
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: Hepatopulmonary 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 liver Hardening, post-necrosis 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, the course of disease And the degree of liver cell damage and complications are different, but the most common clinical manifestations are liver palm, spider mites, jaundice, liver and spleen, ascites, gastrointestinal bleeding, liver dysfunction, etc., but with the liver There is no significant correlation between pulmonary syndrome, and some patients with clinically stable liver disease may 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 vessels. Abnormal changes in the bed, 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 vasodilatation Sheet of the epidermis.
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, sputum 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, Orthostatic hypoxia is the most characteristic manifestation of intrinsic. There is no obvious positive sign in lung examination. A few patients (about 16%-20%) can complain of exercise dyspnea in the absence of clinical manifestations of various liver diseases. Visiting clinics should be paid attention to in order to prevent misdiagnosis. Domestic Gaozhi et al reported that two patients with hepatopulmonary syndrome were treated with cyanosis, flustered after activity, and shortness of breath. The clinical manifestations of cirrhosis (such as liver palm, were found). Spider mites, hepatosplenomegaly, ascites), which 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 Obvious respiratory symptoms should be identified, and data studies have shown that patients with hepatopulmonary syndrome require an average of 2 to 7 years from the initial dyspnea to a definitive diagnosis, and about 18% of patients have a clear diagnosis of liver disease. 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 .
Examine
Examination of hepatopulmonary syndrome
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, and other gastroscopes are still available for discovery. The presence of portal hypertension.
Diagnosis
Diagnosis and differential diagnosis of hepatopulmonary 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.
