Hepatopulmonary syndrome is pathological changes in the pulmonary vessels that occur against the background of chronic liver diseases. The main cause is cirrhosis, less often the condition accompanies chronic hepatitis, cholelithiasis, hepatic vascular pathologies. Symptoms: shortness of breath, increasing in the vertical position of the body, perioral cyanosis and acrocyanosis, deformities of the fingers, similar to “drumsticks” and “watch glasses”. Diagnostics includes transthoracic contrast echocardiography, radioisotope scanning method, angiopulmonography. Supportive treatment involves oxygen therapy and selective embolization of blood vessels, and radical — liver transplantation.
ICD 10
K76.8 Other specified liver diseases
Meaning
Hepatopulmonary syndrome (HPS) is a typical complication of the terminal stage of liver diseases, which in modern hepatology occurs, according to various data, in 4-47% of patients. The large run-up in statistical data is due to the lack of clear diagnostic criteria and the difficulty of early detection of HPS, since its symptoms overlap with the manifestations of the underlying pathology. For the first time, the pathogenetic connection between lung and liver lesions was noticed in 1884 by Dr. M. Flukiger, and 100 years later scientists T.S. Kennedy and R.J. Knudson described in detail the signs of the syndrome.
Causes of hepatopulmonary syndrome
Hepatopulmonary syndrome occurs in 4-19% of patients suffering from cirrhosis of the liver, and 15-20% of people who are waiting in line for organ transplantation. Sometimes pathology develops with untreated chronic hepatitis, complicated course of cholelithiasis. Rare causes include portal hypertension without cirrhosis — with portal vein thrombosis, Budd-Chiari syndrome, congenital hepatic fibrosis. There is no correlation between the severity of the condition and the risk of hepatopulmonary syndrome.
Pathogenesis
The morphological substrate of hepatopulmonary disorders is precapillary-capillary dilation (functional bypass surgery). At the same time, the existing arteriovenous shunts open in the lungs and the microcirculatory bed (“pleural speeders”) expands. In addition, the number of arteriovenous shunts increases in patients, which is associated with the progression of portal hypertension.
An increase in the synthesis of nitric oxide, a substance with pronounced vasodilating properties, plays a central role in the pathogenesis of hepatopulmonary syndrome. Tumor necrosis factor, bacterial lipopolysaccharides, and endothelin-1 are also important in the mechanism of disease development. These substances enhance the production of nitric oxide, contribute to the accumulation of carboxyhemoglobin in the blood and disrupt the diffusion of gases in the lungs.
The result of micro- and macro-changes in the pulmonary parenchyma is a decrease in effective pulmonary ventilation, which is manifested by severe arterial hypoxemia. Due to the lower oxygen saturation of the blood, the respiratory center is activated, which causes tachypnea and other disorders. When compensatory mechanisms fail to cope with increasing hypoxemia, respiratory failure increases in patients.
Symptoms of hepatopulmonary syndrome
The main sign of HPS is pronounced shortness of breath at rest and during exercise. Its distinctive feature is platypnea — a sharp aggravation of symptoms during the transition from horizontal to vertical position, which is caused by a decrease in the partial oxygen voltage in the blood. For this reason, patients with hepatopulmonary disorders do not tolerate even light physical activity, and their quality of life is significantly reduced.
The long—existing hepatopulmonary syndrome is accompanied by signs of respiratory failure: cyanosis of the skin of the nasolabial triangle and fingertips, deformation of the distal phalanges of the fingers in the form of “drumsticks”, and nails – like “watch glasses”. The number of vascular “stars” increases sharply on the skin, which is a sign of systemic vasodilation.
Complications
With the disease, blood oxygenation progressively worsens, ischemia of all internal organs occurs, which exacerbates the phenomena of portal hypertension. Hepatopulmonary syndrome often ends with the death of the patient from respiratory disorders and end-stage liver failure. The average life expectancy of patients with combined hepatic cirrhosis with HPS is 10.6 months, while patients without this syndrome live up to 40.8 months.
Diagnostics of hepatopulmonary syndrome
In the initial diagnosis of a patient with chronic liver disease and complaints of shortness of breath, a pulmonologist performs pulse oximetry. In the case of pO2 drops by 3-10 mm Hg. when changing the horizontal position of the body to the vertical, the doctor may suspect hepatopulmonary syndrome. To verify the diagnosis , the following research methods are prescribed:
- Transthoracic contrast echocardiography. The “gold standard” is used to detect intrapulmonary bypass. The patient is injected with a contrast that forms microbubbles in the vessels. When visualizing these bubbles in the left chambers of the heart, the diagnosis is confirmed, since under physiological conditions they cannot pass through small-diameter pulmonary capillaries.
- Radioisotope scanning. To confirm vasodilation, large particles of albumin are injected into the bloodstream, which normally do not penetrate through the narrow capillaries of the lungs. With intensive arteriovenous shunting, up to 60% of isotope-labeled particles pass through the lung tissue and accumulate in the internal organs.
- Angiopulmonography. In severe hypoxemia, radiopaque imaging of arteriovenous shunts in the lungs is performed as a preparation for invasive treatment. During the study, the doctor examines the condition of the vascular network, assesses the size of large pulmonary arteries and peripheral small vessels.
- Analysis of the gas composition of blood. Hepatopulmonary syndrome is diagnosed with a decrease in carbon monoxide diffusion in the lungs of less than 80% and a decrease in blood oxygen saturation of less than 92%. To confirm the diagnosis, a functional test with pure oxygen is recommended: with intrapulmonary bypass, pO2 is less than 70 mm Hg.
Treatment for hepatopulmonary syndrome
Conservative therapy
Medical treatments are limited. Patients are recommended medications to stabilize the condition and correct the underlying disease, and vasodilator antagonists are also used to slow the progression of hepatopulmonary syndrome. Doctors use the aerosol form of L-NAME and antidepressants from the group of selective serotonin reuptake inhibitors, but they give only temporary improvement.
In clinical practice, to reduce the symptoms of respiratory insufficiency, patients receive respiratory support — intranasal inhalation of moistened oxygen. The method is effective at the initial stage of HPS, but with systemic vasodilation it does not give the desired effect. Experimental studies have shown the effectiveness of joint administration of oxygen therapy and tumor necrosis factor blockers, which improve pulmonary gas exchange.
Surgical treatment
With a moderate degree of respiratory disorders, selective embolization of large arteriovenous shunts is indicated. The intervention is performed to correct the symptoms and improve the quality of life of patients. The only radical method of treatment is orthotopic liver transplantation or liver-lung, liver-lung-heart complexes. In 85% of patients, hepatopulmonary syndrome disappears within a year after organ transplantation.
Prognosis and prevention
Hepatopulmonary syndrome is an unfavorable condition that causes the death of 62-84% of patients who have not had liver transplantation in the first year after diagnosis. After organ transplantation, the prognosis improves, but up to 15% of patients continue to suffer from symptoms of hepatopulmonary syndrome in the post-transplant period. Prevention of the condition consists in early diagnosis and treatment of liver diseases, prevention of cirrhosis and portal hypertension.
