What Are the Causes of Lung Lesions?

Lung manifestations of a disease of the lung itself or of a systemic disease. The respiratory system consists of the respiratory tract (nose, pharynx, larynx, trachea, and bronchi at all levels) and the alveoli. The lungs are the main organs of the respiratory system, and lung diseases are respiratory diseases. In order to complete the metabolism, the human body needs to continuously take in oxygen from the air and exhaust carbon dioxide (gas exchange). This kind of gas exchange is called breathing. Gas exchange and lung ventilation between the lungs and the external environment The gas exchange between the alveoli and blood is called external breathing (also known as lung breathing), and the gas exchange between the blood and the tissue cells or tissue fluid after the gas is transported through the blood Internal breathing (also known as tissue breathing). Therefore, the lungs are closely related to the cardiovascular system. In addition to being responsible for respiratory function, the lungs also have non-respiratory defense, immune and endocrine and metabolic functions.

Lung manifestations of a disease of the lung itself or of a systemic disease. The respiratory system consists of the respiratory tract (nose, pharynx, larynx, trachea, and bronchi at all levels) and the alveoli. The lungs are the main organs of the respiratory system, and lung diseases are respiratory diseases. In order to complete the metabolism, the human body needs to continuously take in oxygen from the air and exhaust carbon dioxide (gas exchange). This kind of gas exchange is called breathing. Gas exchange and lung ventilation between the lung and the external environment The gas exchange between the alveoli and blood is called external breathing (also known as lung breathing), and the gas exchange between the blood and the tissue cells or tissue fluid after the gas is transported to the tissue through the blood is called Internal breathing (also known as tissue breathing). Therefore, the lungs are closely related to the cardiovascular system. In addition to being responsible for respiratory function, the lungs also have non-respiratory defense, immune and endocrine and metabolic functions.

Chinese name: Lung disease

Foreign name: lung diseases
Department: Respiratory Medicine

Causes of lung diseases and common diseases

Lung disease infectious lung disease

The respiratory tract communicates with the outside world, and the whole body's blood flows through the lungs, so the lungs are vulnerable to the invasion of microorganisms inside and outside the body. Respiratory infections caused by viruses and bacteria are the most common. Previously, bacterial pneumonia was mainly infected by Streptococcus pneumoniae, accounting for 80 to 90%. I was caused by Streptococcus, Klebsiella, Staphylococcus and other infections. After the 1970s, the situation of bacterial infections has changed. Although pneumonia outside the hospital is still mainly streptococcus pneumoniae infection, Staphylococcus aureus pneumonia and Gram-negative pneumonia have also increased significantly. Gram-negative bacillus pneumonia in hospitalized patients (due to nosocomial infections) increased significantly, with Klebsiella and Pseudomonas aeruginosa infections being the most common. In addition, fungal infections have also increased. Due to the improvement of microbial isolation and culture technology, pneumonia plastids, anaerobic bacteria, and new pathogenic microorganisms, such as Legionella, Cytomegalovirus, and Pneumocystis, have been successfully diagnosed. Changes in this pathogenic microorganism may be related to the patient's advanced age, severe illness, and increased immune disease; the use of adrenocortical hormones, immunosuppressants, cytotoxic drugs, antibiotics; various intubations, tracheotomy, ventilator applications, and organ Transplant related. Make the original non-pathogenic "non-pathogenic bacteria" into "conditional pathogens": such as patients with acute lymphoblastic leukemia undergoing cytotoxic drug chemotherapy; patients with AIDS have destroyed the function of T lymphocytes due to viral infection Cellular immune deficiency can easily lead to non-pathogenic lung infections, including rare pulmonary sporozoites.

Tuberculosis is a common disease of chronic bacterial lung infections. In recent years, due to the discovery and rational use of effective anti-TB drugs, the morbidity and mortality have decreased significantly. According to statistics from the International Federation of Tuberculosis Prevention, the incidence is still high in some countries, and about 4 million highly infectious patients are found every year, and there are 4 million new tuberculosis patients who do not excrete bacteria. There are approximately 20 million active TB patients worldwide, and 3 million die each year from TB. Tuberculosis is still one of the infectious diseases that threaten human health.

Lung diseases related to air pollution and smoking

Under normal circumstances, dry air contains about 78% nitrogen, 21% oxygen, 0.93% argon, 0.03% carbon dioxide, and trace gases such as neon, helium, and hydrogen, which are necessary conditions to maintain the normal function and health of the human body. Due to the development of modern industry and transportation, the combustion of coal, oil, and natural gas, and industrial waste gas, etc., have caused more than 100 types of atmospheric pollutants. The main ones are coal dust, carbon monoxide, sulfur dioxide, nitrogen oxides, and peroxides. , Hydrogen sulfide, hydrocarbons and benzopyrene of polycyclic hydrocarbons. Because the respiratory tract is in direct contact with the atmosphere, it also suffers the most. Pollutants such as sulfur dioxide, nitrogen oxides, and peroxides can stimulate the respiratory tract, which can cause bronchospasm and increased secretion of respiratory mucus, which increases respiratory resistance, weakens or disappears the cilia of the respiratory mucosa, and reduces the resistance of the respiratory tract to microorganisms. The onset of chronic obstructive pulmonary disease (COPD including chronic bronchitis, obstructive emphysema) is related to air pollution.

Emphysema is a common disease of the respiratory system, and the pathological change is the dilation and destruction of the air cavity in the distal bronchioles. Human elastase mainly comes from neutrophils, and alveolar macrophages are less abundant. Antielastase also has many substances, the most important of which is alpha ₁ antitrypsin. Lack of hereditary alpha ₁ antitrypsin can cause emphysema, but the number is small, accounting for only 1% of the total number of patients with chronic obstructive pulmonary disease. The main pathological change is panlobular emphysema. This type of emphysema occurs at an earlier age and progresses more quickly.

Long-term smoking can also cause emphysema. Tobacco smoke contains thousands of chemicals, including high concentrations of toxic substances, some of which are suspended in the air in particulate form. Inhalation of the respiratory tract results in thickened bronchial epithelium and degenerative changes, inhibits ciliary movement, ciliary shedding, necrosis, hypertrophy of mucus glands, increased secretion, and reduced alveolar phagocytosis. Peroxide and oxygen free radicals in the smoke can oxidize ₁ antitrypsin, so smoking can inactivate ₁ antitrypsin. Smokers have 60% of the activity of ₁ antitrypsin. At the same time, smoking can stimulate alveolar macrophages to produce neutrophil chemokines, cause neutrophils to accumulate in the lungs, release a large amount of elastase, and then destroy lung tissue to form lobular central emphysema.

Studies have found that malnutrition can affect protein synthesis and affect the structure of elastic fibers to make them easier to break down. Excessive stress and malnutrition can affect the production of anti-proteases, resulting in a temporary lack of anti-proteases. Copper, iron, and selenium trace elements, as well as vitamin C and E deficiency, can affect the dynamic balance of protease-antiprotease through the antioxidant system, leading to lung tissue damage.

In patients with chronic obstructive emphysema, due to the imbalance between energy supply and demand, respiratory muscle fatigue occurs, and the structure and function of respiratory muscles are damaged to varying degrees, causing acute or chronic type respiratory failure.

Air pollution and smoking are also vital to the increased incidence of lung cancer. For example, benzopyrene, nitrogen oxides and nitrated olefins produced by the interaction of nitrogen oxides with olefins, asbestos, arsenic, chromium, and nickel are all related to the occurrence of cancer.

Pulmonary diseases related to occupational lung diseases

In some occupations, lung damage caused by inhalation of harmful dust, smoke or poison is an occupational lung disease.

Long-term inhalation of harmful dust-silicon dioxide (that is, quartz), silicate, coal, iron, tin, etc. can form deposits in the lungs, called pneumoconiosis. Some pneumoconiosis is a benign process, and some serious disease can lead to pulmonary fibrosis. Among the pneumoconiosis, silicosis, coal silicosis, and asbestos lung are the most important. Certain metals such as beryllium, mercury, cadmium, manganese, nickel and other vapors, fumes, oxides or salts can cause lung poisoning when inhaled. Acute reactions caused by beryllium and its compounds are extensive invasive lesions of the alveoli, and chronic beryllium poisoning is a granulomatous change. Certain organic dusts such as cotton dust and isocyanates and platinum salts can cause occupational asthma. Sulfur dioxide, nitrogen dioxide, ammonium, hydrochloric acid, chlorine, and phosgene can cause bronchitis and pneumonia. Harmful gases and strong acid fumes can also cause pulmonary edema. Uranium, nickel, chromate, asbestos, and dichloromethyl ether are closely related to the incidence of lung cancer. Pleural mesothelioma is associated with long-term exposure to asbestos.

Lung Diseases Immune-related Lung Diseases

The respiratory system has a complete set of defense systems. When exposed to external allergens, protective immune and allergic reactions can occur in the lungs. Bronchial asthma is most common in allergic lung diseases. Especially in developed countries, the prevalence of bronchial asthma is generally increasing. Exogenous asthma is caused by the invasion of antigenic substances in vitro, such as pollen, dust, industrial chemicals or drugs and other specific antigenic substances. If you leave this environment or use this substance as a desensitization therapy, some patients can be relieved. Patients with endogenous asthma are mostly based on certain genetic qualities, poor physiques, or mental effects. As the respiratory tract is often infected or stimulated by certain substances, the reactivity of the bronchial mucosa is increased, and certain irritants during climate change or inhalation It is difficult to distinguish it from wheezing bronchitis when it occurs on the body, and the prognosis is poor. Subtilia, also known as allergic rhinitis, is a common upper respiratory tract allergic disease caused by various pollen antigens in the nasal, eye, and throat mucosa. Exogenous allergic alveolitis is an allergic inflammation of the alveolar wall caused by inhalation of organic dust. Mainly manifested as acute, subacute or chronic interstitial pneumonia with granulomatous lesions. Such as farmers exposed to moldy straw, feed, grains, compost, farmers' lungs, mushroom lungs caused by micropolysporum, thermophilic actinomyces antigens, and people exposed to pigeons, parrots and other bird excreta and feathers The bird feeder's lung caused by guano and bird serum protein antigens, both of which are exogenous allergic alveolitis. Pulmonary hemorrhagic nephritis syndrome, also known as Good Pasteur's syndrome, is caused by a viral infection or some unknown cause that changes the glomerular basement membrane antigenicity or promotes the exposure of the antigenic substance in the basement membrane to the patient's blood circulation. Anti-renal basement membrane antibodies are produced in combination with the glomerulus and alveolar capillary basement membranes. The deposition of IgG-based and C3 complement causes alveolar wall lesions, alveolar hemorrhage and fibrin exudation, and rapid development of small renal cells. Glomerulonephritis can die from hemoptysis, respiratory failure or renal failure. The migration of worm worms in the lungs can cause allergic pulmonary infiltration. Connective tissue diseases Systemic lupus erythematosus, rheumatoid arthritis and other pulmonary diseases and diffuse fibrosing alveolitis, necrotizing granuloma, eosinophilic granuloma are all related to immune response.

In recent years, pulmonary interstitial disease has an increasing trend, most of which are unknown. The pathological process is the toxic effect of direct contact with the substance, or through inflammation and immune response. It starts as alveolitis. The disease changes from acute to chronic, and finally the pulmonary interstitial fibrosis. In severe cases, the alveolar structure is damaged, forming a cystic change. It looks like a honeycomb, so it is called honeycomb lung, which is prone to recurrent lung infections and can die from lung infections or respiratory failure.

Lung Diseases Genetically Related Lung Diseases

Emphysema caused by hereditary alpha ₁ antitrypsin deficiency. Recessive genetic diseases, such as pulmonary fibrosis and cystic changes during pancreatic cystic fibrosis, are more common in Europeans and Americans, and rare in Eastern nations. In hereditary Cartagena syndrome, respiratory epithelial cilia are immobile and are therefore prone to respiratory infections.

Lung disease

Divided into benign and malignant. The most common malignant tumor is primary bronchial lung cancer (lung cancer for short), which accounts for about 90% of lung tumors. Followed by lung metastatic cancer, mostly from urogenital organs, gastrointestinal, thyroid, breast and so on. Benign tumors of the lung such as hamartoma, lipoma, and papilloma are rare. In recent years, the incidence and mortality of lung cancer have increased significantly. In developed countries, lung cancer has the most common malignant tumors in men, and the second and third most common malignant tumors in women. The cause of lung cancer is not clear, but its onset is known to be closely related to long-term smoking, air pollution, and exposure to certain physical and chemical carcinogens (such as coal tar, asphalt, asbestos, radioactive uranium, radium derivatives, radon, and radon daughter bodies). It is also related to chronic lung inflammation, viral infection, vitamin A deficiency, low immune function, endocrine disorders and family genetics. In recent years, many advances have been made in the etiology, pathology, early diagnosis and comprehensive treatment of lung cancer.

Lung disease of unknown cause

Such as sarcoidosis, alveolar proteinosis, alveolar microlithiasis and so on.

Pulmonary manifestations of systemic diseases

Cardiogenic pulmonary edema can occur in left heart failure caused by a variety of causes. Traumatic shock and severe infection can cause diffuse pulmonary capillary damage and cause pulmonary interstitial and alveolar edema, manifested as adult respiratory distress syndrome. Hypoproteinemia (such as cirrhosis, nephrotic syndrome, etc.) can cause pleural effusion (leakage), and patients with acute pancreatitis can also develop pleural effusion and diffuse lung disease. Connective tissue disease, lymphoma, malignant histiocytosis, leukemia, rheumatism, etc. can have the performance of pulmonary or pleural effusion.

Differential diagnosis of lung disease

X-ray tomography and computed tomography (CT) provide a clearer understanding of lung shadows, mass shapes, and properties. Fiber bronchoscopy, if necessary, can also be used to perform pathological, bacterial, and biochemical tests through skin puncture lung biopsy tissues, which greatly improves the diagnosis rate of etiology. Bronchoalveolar lavage fluid can be used to count, sort, and determine immune antibodies, complements, and enzymes in the liquid under the microscope to help understand the nature of the disease. Lung scan using radionuclide Ga (gallium): Ga can be concentrated in metabolically active sites and used clinically to diagnose lung cancer, sarcoidosis, and interstitial alveolitis. And can be used to identify pulmonary infarction and pneumonia. Pulmonary angiography is helpful in the diagnosis of pulmonary infarction.

Lung disease test

Pulmonary function measurement: small airway and small airway function measurement: small airway refers to the bronchioles with an inner diameter of the airway equal to or less than 2 mm in the inhaled state. Methods to check the function of small airways include closed air volume, total closed air volume, phase III slope, and maximum expiratory flow-volume curve. Through these inspection methods, obstructive pulmonary disease can be detected early, and it can also be used to monitor the harm to the lungs from smoking and air pollution, and to study the physiology of breathing. Determination of regional differences in lung function: due to the advancement of radionuclide technology, the use of electronic computers and the application of inert gases with different dissolution coefficients can measure lung ventilation, blood flow, and ventilation / blood flow ratios.

Lung disease treatment principles

In terms of clinical treatment: new drug applications, such as various new antibiotics, anti-tuberculosis drugs, adrenal corticosteroids, asthma drugs; blood gas analysis, the role of the ventilator; establishment of a respiratory monitoring room, which improves lung infections, respiratory failure and other diseases Level of diagnosis and treatment.