Hepatopulmonary syndrome

　　The causes of hypoxemia in liver diseases include various acute and chronic liver diseases that can be accompanied by pulmonary vascular abnormalities and arterial hypoxemia, the most important being liver cirrhosis caused by chronic liver disease, especially cryptogenic cirrhosis, alcoholic cirrhosis, hepatitis cirrhosis, and primary biliary cirrhosis. Portal hypertension may be the main pathogenic factor of hepatopulmonary syndrome, but it has not been found to be correlated with the severity of liver cirrhosis. The occurrence and development of hepatopulmonary syndrome are the result of the interaction of multiple factors, and cannot be explained simply by portal hypertension or liver dysfunction.

　　The pathogenesis of hepatopulmonary syndrome is related to the decreased affinity of oxygenated hemoglobin, pulmonary capillary dilation caused by prostaglandins and other vasodilatory factors, intrapulmonary (arteriovenous and portal-pulmonary vein) shunting, limited oxygen diffusion in alveoli and capillaries, imbalance of ventilation/perfusion ratio, and compression of chest and abdominal fluid pressure. The main lesions are pulmonary vascular dilation and pulmonary circulation disorder, with multiple anastomotic branches in the peripheral vascular bed around the pulmonary hilum and large arteries and veins near the pulmonary hilum, allowing mixed venous blood to enter the pulmonary veins through them.

　　Patients with liver-pulmonary syndrome are prone to complications such as liver cirrhosis, viral hepatitis, toxic hepatitis, and hepatolenticular degeneration. Diseases affect patients' daily lives and harm their health, so timely treatment is essential.

　　Since liver-pulmonary syndrome is a triad consisting of pulmonary vascular dilation and insufficient arterial oxygenation caused by primary liver disease, its clinical manifestations are mainly characterized by primary liver disease and pulmonary lesions.

　　1. Clinical manifestations of primary liver disease

　　Liver-pulmonary syndrome can occur in various liver diseases, but it is most common in chronic liver disease, especially in liver cirrhosis caused by various reasons, such as cryptogenic cirrhosis, alcoholic cirrhosis, hepatitis cirrhosis, postnecrotic cirrhosis, and biliary cirrhosis, etc. The majority of patients (about 80%) present with the clinical manifestations of various liver diseases, and at this time, there are still no respiratory system symptoms. The clinical manifestations of various liver diseases vary greatly due to the cause, course, degree of liver cell function damage, and complications. The most common clinical manifestations include palmar erythema, spider angioma, jaundice, splenomegaly, ascites, gastrointestinal bleeding, and abnormal liver function, but there is no obvious correlation with liver-pulmonary syndrome. Some patients with relatively stable liver disease in clinical practice may also have progressive decline in pulmonary function. Data show that in chronic liver disease and cirrhosis patients, the appearance of spider angioma may indicate abnormal changes in the pulmonary vascular bed. Some people even believe that individuals with the sign of spider angioma have obvious systemic and pulmonary vascular dilation and severe gas exchange disorders, suggesting that they may be the epidermal marker of pulmonary vascular dilation.

　　2. Clinical manifestations of pulmonary dysfunction

　　Due to the absence of primary cardiovascular and pulmonary diseases in patients with this condition, the majority (80% to 90%) of patients gradually develop respiratory system manifestations on the basis of various liver diseases, such as cyanosis, dyspnea, clubbing (of fingers or toes), orthostatic hypoxia, and supine breathing (platypnea), among which progressive dyspnea is the most common pulmonary symptom of liver-pulmonary syndrome. Binay et al. believe that cyanosis is the only reliable clinical sign, while supine breathing and orthostatic hypoxia are the most characteristic manifestations of this syndrome. Pulmonary examination generally shows no obvious positive signs, and a few patients (about 16% to 20%) may present with exertional dyspnea as the main complaint without clinical manifestations of various liver diseases. Clinically, attention should be paid to prevent misdiagnosis. Chinese Gao Zhi et al. have reported two cases of liver-pulmonary syndrome patients who presented with cyanosis, palpitations after exercise, and shortness of breath as the main complaints. It was found that they were accompanied by clinical manifestations of liver cirrhosis (such as palmar erythema, spider angioma, splenomegaly, ascites), which is conducive to the diagnosis of this disease. If liver disease patients simultaneously have other pulmonary diseases (such as chronic bronchitis, emphysema, pneumonia, pleural effusion, etc.), they may coexist with liver-pulmonary syndrome, resulting in obvious respiratory symptoms, and attention should be paid to differential diagnosis. Some research data show that it takes an average of 2 to 7 years for patients with liver-pulmonary syndrome to be diagnosed from the initial onset of dyspnea to the clear diagnosis, and about 18% of patients may have dyspnea at the time of clear liver disease diagnosis.

　　(1) Orthostatic hypoxemia

　　When patients change from supine to standing position, PaO2 decreases by more than 10%.

　　(2) Supine breathing

　　When patients change from supine to standing position, symptoms such as palpitations, chest tightness, and shortness of breath occur. When patients return to the supine position, the above symptoms improve. According to Krowka's report, about 80% to 90% of liver-lung syndrome patients show the above two manifestations. This is due to the expansion of pulmonary blood vessels in liver-lung syndrome patients mainly distributed in the middle and lower lung fields. When patients change from supine to standing position, under the action of gravity, the blood flow in the middle and lower lungs increases, which aggravates the hypoxemia caused by the low oxygen level. Although the above two manifestations are not unique to liver-lung syndrome, they indicate that there is a significant abnormality in the patient's pulmonary vascular system. If various liver disease patients show the above two manifestations, further examination should be performed to confirm.

　　To prevent liver-lung syndrome, it is necessary to actively prevent liver disease, actively participate in various sports activities, and improve self-immunity. Regularly consuming mushrooms, mushrooms, jujube, ganoderma lucidum, and green beans (dolichos lablab) is beneficial to improve immunity, break the virus tolerance state; pay attention to a diet high in protein and vitamins. Avoid long-term overwork, maintain sufficient sleep, and generally work and study can be done. Abstain from alcohol and avoid all drugs that damage the liver.

　　1) Bed rest

　　Maintain a high pillow semi-recumbent or lateral position, avoid lying flat, to prevent abdominal fluid from compressing the kidneys.

　　2) Dietary supplementation with high-quality protein

　　The amount of protein supply should be sufficient for the patient to tolerate and maintain nitrogen balance, promote liver cell regeneration without inducing hepatic encephalopathy.

　　3) Maintain the frequency of bowel movements

　　Keep bowel movements 2 to 3 times a day, and pay attention to color changes to prevent the accumulation of blood ammonia. If the stool is bright red or black, it indicates bleeding and should be reported to the doctor for hemostatic treatment.

　　4) Monitor pulse and blood pressure

　　Patients with liver-kidney syndrome and their families should learn to correctly measure the pulse and blood pressure to facilitate the continued monitoring of vital signs after discharge.

　　5) Limit the intake of sodium

　　Accurately record the intake and output of water every day, and especially pay attention to the total amount, color, and specific gravity of urine.

　　6) Keep the mood pleasant

　　According to traditional Chinese medicine, changes in mood can directly affect the physiological function of the viscera. For example, excessive anger can damage the liver, excessive worry can damage the spleen, and fear can damage the kidneys. Therefore, maintaining an optimistic mood and avoiding adverse stimuli can prevent the recurrence or worsening of the disease.

　　Liver-lung syndrome is characterized by primary liver disease and pulmonary lesions. The characteristic manifestations of liver-lung syndrome are orthostatic dyspnea, hypoxemia, cyanosis, and the following auxiliary examinations:

　　1. Pulmonary function test

　　The lung vital capacity, maximum ventilation volume, functional residual capacity, total lung capacity, respiratory reserve volume, R/T, one-second forced expiratory volume, carbon monoxide diffusion capacity in the lung, and other parameters can be measured. In patients with liver-lung syndrome without significant pleural or peritoneal effusion, although the lung volume and ventilation volume can be basically normal, there is still a significant change in diffusion capacity, which remains significantly abnormal even after correction for hemoglobin.

　　Arterial blood gas analysis: in liver-lung syndrome, the alveolar oxygen partial pressure decreases, less than 70mmHg; SaO2 decreases, less than 90%. When standing or lying flat, PaO2 decreases, more than 10mmHg; A-aPO2 gradient increases by 15-20mmHg. The measurement of PaO2 when breathing indoor air and 100% oxygen is also of great value. A-aPO2 is more sensitive than PaO2 and can be used as the main diagnostic basis for liver-lung syndrome.

　　2, Echocardiographic scan

　　Echocardiography through the chest wall and esophagus can differentiate the location of the lesion, with esophageal echocardiography being more sensitive than chest wall echocardiography and having a correlation with gas exchange disorders.

　　3, Pulmonary angiography

　　Type I: diffuse pre-capillary arteriolar dilation: diffused spider-like images, diffused spongy or stain-like images, inhaling 100% oxygen can increase PaO2.

　　Type II: intermittent local arterial malformations or collaterals: isolated worm-like or mass-like images, inhaling 100% oxygen has no effect on PaO2.

　　4, CT examination

　　CT scans of patients with liver-lung syndrome can show pulmonary distal vascular expansion, with a large number of abnormal terminal branches, which can suggest the presence of liver-lung syndrome, but it is not specific.

　　5, Chest X-ray

　　The manifestations of liver-lung syndrome are non-specific. Standing X-ray chest films can show interstitial infiltration at the base of both lungs, which is a shadow of vascular expansion, disappearing when lying flat, and needs to be differentiated from pulmonary interstitial fibrosis.

　　What kind of food is good for liver-lung syndrome? A reasonable diet plays an important role in the care of the lungs. As early as the 'Neijing', there were views such as 'drinking excessively will reverse the qi' and 'drinking cold drinks when the body is cold will harm the lungs', and also proposed the theory of 'five grains as nourishment, five fruits as assistance, five animals as benefit, five vegetables as filling, and taking them together with the right flavor to nourish the essence and Qi'. The general principle of lung-nourishing food therapy is to eat less spicy and heavy foods, choose light and nutritious foods, emphasize less salt and avoid saltiness, and do not eat foods that are too cold or too hot, especially cold drinks.

　　Traditional Chinese medicine believes that there are many foods that can nourish the lungs in daily life. For example, pears have the effects of clearing phlegm and stopping coughs, calming the mind and moistening the lungs, and detoxifying and diuretic. Radishes can treat symptoms such as lung heat and coughs, thick phlegm, etc. Silver ear can treat symptoms such as yin deficiency and dry lungs, dry cough, thick phlegm, etc. Lily can alleviate symptoms such as cough, insomnia, and neurasthenia. Water chestnuts are effective for symptoms such as injury to the fluid, phlegm heat, and cough. In addition, there are many foods with lung-nourishing properties, including glutinous rice, Job's tears, soy milk, tofu skin, ginger, scallion, onion, carrots, white fungus, mushrooms, chrysanthemum leaves, bamboo shoots, winter melon, yam, coriander, silver carp, loach, seaweed, pork lung, pork skin, goose meat, duck meat, honey, rock sugar, etc. Fruits and vegetables include sugarcane, grapes, jujube, pomegranate, loquat, tangerine, persimmon, walnut, myrtle, kiwi, hawthorn, jujube, lemon, olive, etc. In daily life, people can choose according to their specific conditions. The above information is for reference only, and detailed information should be consulted with a doctor.

　　General treatment for hepatic pulmonary syndrome (HPS) includes treating the primary disease, improving liver function or delaying the progression of cirrhosis, reducing portal vein pressure, which may reduce the right-to-left shunting in the lungs.

　　1. Oxygen Therapy and Hyperbaric Oxygen Chamber

　　It is suitable for mild, early HPS patients and can increase the oxygen concentration and pressure in the alveoli, which is helpful for oxygen diffusion.

　　2. Embolization Treatment

　　It is suitable for the embolization of isolated pulmonary arteriovenous communications, i.e., type II HPS patients according to pulmonary angiography.

　　3. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

　　It can improve oxygenation in HPS patients, significantly improve PaO2 and alveolar-arterial oxygen pressure difference, and improve the symptoms of dyspnea. For HPS patients waiting for orthotopic liver transplantation, TIPS can reduce perioperative mortality and improve surgical safety.

　　4. Orthotopic Liver Transplantation

　　Orthotopic liver transplantation is the fundamental treatment for HPS. It can reverse pulmonary vascular dilation. Progressive hypoxemia associated with HPS can be an indication for liver transplantation. Kaspar et al. recently reported that the oxygen partial pressure, oxygen saturation, and pulmonary vascular resistance of patients after orthotopic liver transplantation were significantly improved.

　　5. Drug Treatment

　　The progress of drug treatment for HPS is slow, and the efficacy is not satisfactory. Octreotide is a potent vasodilatory neuropeptide inhibitor, believed to reduce pulmonary arteriovenous shunting in HPS patients by blocking neuropeptides, vasoactive peptides, and inhibiting glucagon. Alprenolol can improve the ventilation/perfusion ratio in chronic obstructive pulmonary disease, causing hypoxic pulmonary vessels to constrict and thus improve the ventilation/perfusion ratio. Methylene blue clinical application can increase pulmonary vascular resistance and systemic vascular resistance, improve hypoxemia and hyperdynamic circulation in HPS patients. Currently, drug treatment has not been recognized.