What Is Hepatopulmonary Syndrome?

Hepatopulmonary syndrome (HPS) is caused by chronic liver disease and / or portal hypertension due to abnormal dilation of pulmonary blood vessels, gas exchange disorders, and abnormal arterial blood oxygenation, resulting in hypoxemia and a series of pathophysiological changes. And clinical manifestations, clinical features are: the exclusion of the triad of primary cardiopulmonary disorders-basic liver disease, pulmonary vasodilation and arterial oxygenation dysfunction. Abnormal arterial blood oxygenation caused by pulmonary gas exchange disordersalveolar gas-arterial blood oxygen partial pressure rise and hypoxemia are important physiological foundations of hepatopulmonary syndrome. Hepatopulmonary syndrome is a serious pulmonary complication of end-stage liver disease.

Basic Information

English name: hepatopulmonary syndrome, HPS
Visiting department: Internal medicine
Multiple groups: Liver and lung

Common causes: Various acute and chronic liver diseases can be accompanied by pulmonary vascular abnormalities and arterial hypoxemia
Common symptoms: Orthostatic dyspnea, hypoxemia, cyanosis

Causes of liver and lung syndrome

Causes of liver diseases that cause hypoxemia: A variety of acute and chronic liver diseases can be accompanied by pulmonary vascular abnormalities and arterial hypoxemia. The most important is liver cirrhosis caused by chronic liver disease, especially cryptogenic cirrhosis, alcoholic Cirrhosis, hepatitis cirrhosis, and primary biliary cirrhosis. Portal hypertension may be the main cause of hepatopulmonary syndrome, and it has not been found to be related to the severity of liver cirrhosis. The occurrence and development of hepatopulmonary syndrome is the result of a variety of factors, which cannot be explained solely by portal hypertension or liver dysfunction.

Clinical manifestations of liver and lung syndrome

The disease is a triad of pulmonary vasodilation and arterial oxygenation caused by primary liver disease. Clinically, it is characterized by primary liver disease and lung disease. The characteristic manifestation of hepatopulmonary syndrome is orthostatic dyspnea, Hypoxemia, cyanosis.

Clinical manifestations of primary liver disease

Due to the degree of damage to liver cell function and complications, liver palms, spider moles, jaundice, hepatosplenomegaly, peritoneal effusion, gastrointestinal bleeding, and abnormal liver function are the most common. Hepatopulmonary syndrome has nothing to do with the etiology and degree of liver disease, and some patients with stable liver disease may also show progressive decline in pulmonary function. Pulmonary vasodilation (pulmonary spider nevus) is often found in patients with liver disease with subcutaneous spider nevus, which is prone to hypoxemia. Subcutaneous spider nevus is considered to be a sign of extrahepatic invasion.

2. Clinical manifestations of pulmonary dysfunction

The patients had no primary cardiopulmonary disease, and most of them gradually developed respiratory manifestations based on liver disease, such as cyanosis, dyspnea, clubbing fingers (toes), orthostatic hypoxia, and supine breathing. Progressive dyspnea is the most common pulmonary symptom of hepatopulmonary syndrome, and cyanosis is the only reliable clinical sign. Supine breathing and orthostatic hypoxia are the most characteristic manifestations of this disease. Pulmonary examinations generally show no significant positive signs.

Liver and lung syndrome examination

Pulmonary function measurement

Can measure vital capacity, maximum ventilation, functional residual capacity, total lung capacity, respiratory reserve volume, R / T, forced expiratory volume in one second, lung carbon monoxide dispersion and so on. In patients with hepatopulmonary syndrome without obvious thoracic or abdominal effusion, although the lung volume and expiratory volume can be basically normal, there is still a significant change in the amount of diffusion, even after hemoglobin correction is still abnormal.

Arterial blood gas analysis: Alveolar oxygen partial pressure decreased in hepatopulmonary syndrome, less than 70mmHg; SaO ₂ decreased, less than 90%. PaO ₂ decreased in the upright and supine positions and was greater than 10 mmHg; the gradient of A-aPO ₂ increased by 15-20 mmHg. The determination of PaO ₂ when breathing room air and 100% oxygen is also of great value. A-aPO ₂ is more sensitive than PaO ₂ and can be used as the main diagnostic basis for liver and lung syndrome.

2. Echocardiography

Transthoracic echocardiography and transesophageal echocardiography can identify lesions. Transesophageal echocardiography is more sensitive than transthoracic echocardiography and has a correlation with gas exchange disorders.

3. Pulmonary angiography

Type -diffuse anterior capillary dilatation: diffusely distributed spider-like images, diffusely distributed sponge-like or stain-like images, and 100% oxygen can increase PaO2. Type -intermittent local arterial malformation or communication branch: isolated earthworm-like or lump-like image, 100% oxygen absorption has no effect on PaO ₂ .

4.CT inspection

CT of patients with hepatopulmonary syndrome can show distending blood vessels in the distal lung, with a large number of abnormal peripheral branches, which can indicate the presence of hepatopulmonary syndrome, but it is not specific.

5. Chest X-ray

Hepatopulmonary syndrome has no specific manifestations. X-ray chest radiographs can show interstitial infiltration at the base of both lungs in the standing position, which is the shadow of vasodilatation. It disappears when lying down. .

Liver and lung syndrome diagnosis

Hepato-pulmonary syndrome can be diagnosed if:

1. Acute and chronic liver diseases, liver dysfunction may not be obvious.

2. No primary cardiopulmonary disease, normal chest X-ray or interstitial nodular shadow.

3. Abnormal lung gas exchange, with or without hypoxemia, A-aPO2 gradient greater than 15mmHg.

4. Contrast-enhanced echocardiography scan and / or lung perfusion scan, pulmonary angiography, pulmonary vasodilation and / or pulmonary vascular short circuit.

5. Hypoxia, shortness of breath, cyanosis, pulmonary bone and joint disease in the upright position.

Hepatopulmonary syndrome treatment

General treatment

These include treating the primary disease, improving liver function or delaying the progression of cirrhosis, reducing portal vein pressure, and possibly reducing right-to-left shunts in the lungs.

2. Oxygen inhalation and hyperbaric oxygen chamber

It is suitable for patients with mild and early hepatopulmonary syndrome. It can increase the oxygen concentration and pressure in the alveoli and help oxygen diffusion.

3. Embolization

It is suitable for the embolization of isolated pulmonary arteriovenous communication branches, that is, patients with hepatopulmonary syndrome of pulmonary angiography type II.

4. Transjugular intrahepatic portosystemic shunt (TIPS)

It can improve the oxygenation of patients with hepatopulmonary syndrome, PaO ₂ and alveolar arterial oxygen partial pressure can be significantly improved, and the symptoms of dyspnea in patients can be improved.

5. Orthotopic liver transplantation

It is a fundamental treatment for hepatopulmonary syndrome, which can reverse pulmonary vasodilation. Hepato-pulmonary syndrome with progressive hypoxemia can be used as an indication for liver transplantation.

6. Drug treatment for liver and lung syndrome

Progress is slow and the results are not satisfactory. Octreotide is a potent vasodilator neuropeptide inhibitor. It is thought that it can reduce the pulmonary arteriovenous shunt in patients with hepatopulmonary syndrome by blocking neuropeptides, vasoactive peptides and inhibiting glucagon. Allyl piperazine can improve the ventilation / blood flow ratio of chronic obstructive pulmonary disease, and can make hypoxic pulmonary blood vessels constrict, thereby improving the pulmonary ventilation / blood flow ratio. Methylene blue clinical application can increase pulmonary vascular resistance and systemic vascular resistance, improve hypoxemia and hyperdynamic circulation in patients with liver and lung syndrome. At present, no medical treatment has been recognized.