Senile interstitial pneumonia

　　The causes of senile interstitial pneumonia are related to the following factors:

　　1. Inhaled inorganic dust:Silica, asbestos, talc, antimony, beryllium, coal, aluminum, tin, iron.

　　2. Inhaled organic dust:Mold dust, sugarcane dust, mushroom lung, pigeon breeder's disease, cotton dust, synthetic fibers, and wood plastic radiation damage.

　　3. Microbial infections:Viruses, bacteria, fungi, Pneumocystis carinii pneumonia, parasites.

　　4. Medications:Cytotoxic chemotherapy drugs, busulfan, cyclophosphamide.

　　5. Malignant lymphangitis, pulmonary edema.

　　6. Inhaled gases:Oxygen, sulfur dioxide, chlorine, nitrogen oxides, dust, lipids, and mercury vapor.

　　The causes of diseases include occupational exposure, among which inorganic dust is the most common cause, and the number of cases caused by organic dust is increasing. Diseases caused by organic dust are also known as allergic alveolitis, which often occurs due to a history of allergy, when the patient inhales foreign proteins or polysaccharides. The causes of idiopathic pulmonary fibrosis, sarcoidosis, and collagen vascular diseases are the most common, followed by histiocytosis, pulmonary-renal syndrome, pulmonary vasculitis, and idiopathic hemosiderosis. Unknown causes account for 2/3 of all cases.

　　Elderly interstitial lung disease is prone to complications such as respiratory failure and pleurisy, as follows:

　　Firstly, respiratory failure

　　Severe elderly patients with emphysema are prone to respiratory muscle fatigue due to increased work of breathing, flattened diaphragm, increased curvature radius, and malnutrition. On this basis, respiratory failure may often be induced due to lower respiratory tract infections, associated diseases, surgery, fatigue, and other factors. Improper use of oxygen therapy, sedatives, cough suppressants, and other iatrogenic factors may also trigger respiratory failure.

　　Secondly, pleurisy

　　Mild cases may be asymptomatic. The main clinical manifestations include chest pain, cough, chest tightness, and shortness of breath, which may even lead to respiratory distress. In cases of secondary infection due to infectious pleurisy or pleural effusion, symptoms such as chills and fever may occur. The clinical manifestations of pleurisy caused by different etiologies may be accompanied by symptoms of the corresponding diseases, and the most common symptom of pleurisy is chest pain.

　　Interstitial lung disease in the elderly usually has an insidious onset, with progressive worsening of exertional dyspnea being the most common symptom, usually accompanied by dry cough and a tendency to fatigue. The main signs include shallow and rapid breathing, crepitus primarily in the lower lungs, cyanosis of the lips and fingers, and clubbing (of toes). In the late stage, pulmonary hypertension and hypertrophy of the right ventricle may occur, and death often results from respiratory failure or (and) heart failure.

　　At present, there is no way to prevent interstitial lung disease (ILD) in the elderly whose etiology is unknown. However, smokers are at an increased risk of developing idiopathic pulmonary interstitial fibrosis. The prevention of ILD with known etiology should focus on monitoring various personnel working in environments with large amounts of dust, those who have long-term contact with strong irritant gases such as chlorine, ammonia, carbon dioxide, formaldehyde, and various acid mists, as well as radioactive damage, and bird breeders. Regular lung function tests, blood gas analysis, and routine X-ray examinations should be conducted to detect the disease early and treat it promptly.

　　The inhalation of various microorganisms, particles, allergens such as heterologous proteins, and harmful irritant gases in the air can also cause lung damage. Clinical observations show that the onset process of ILD (Interstitial Lung Disease) is sometimes very slow, and it is common to encounter patients who had been exposed to dust or toxins in their youth but only developed obvious symptoms in their old age. For these elderly patients, due to weakened immune function, poor nutritional status, and the presence of underlying diseases such as heart, lung, and kidney conditions, treatment is very difficult and the mortality rate is very high. Reduced physical activity in the elderly may mask symptoms such as dyspnea and shortness of breath caused by this disease, so for the high-risk population of this disease, it is necessary to take on health care functions at the family level and within the community, conducting regular health education and health consultations.

　　The specific clinical examination for senile interstitial pneumonia is as follows:

　　One, blood tests

　　The inflammatory and immunocellular abnormalities in the alveolar structure of ILD are not associated with other extrapulmonary lesions. Many patients have an increased erythrocyte sedimentation rate or increased blood immunoglobulins, which are not closely associated with pulmonary fibrosis. Some patients may have immune complexes detected in the serum, which are produced in the lungs and overflow. A portion of patients have positive rheumatoid factors and antinuclear antibodies, and some patients have anti-pulmonary collagen antibodies in the serum. Arterial blood gas analysis: Due to reduced tidal volume, increased respiratory rate, shallow and rapid breathing, insufficient alveolar ventilation, leading to a decrease in the ventilation/perfusion ratio, hypoxemia occurs, but the partial pressure of carbon dioxide in arterial blood is normal. After exercise, the arterial oxygen partial pressure decreases significantly. Bronchial alveolar lavage examination: A fiberoptic bronchoscope is inserted into the left lingular lobe or right middle lobe of the lung, and physiological saline is infused for lavage to obtain bronchial alveolar lavage fluid. The lavage fluid is tested for cytological and non-cytological components.

　　Two, chest X-ray examination

　　One of the common methods for diagnosing ILD is to show hazy shadows in the lower lungs fields with increased density like sandblasted glass in the early stage of alveolar inflammation. Due to the unobvious early clinical symptoms, patients rarely seek medical attention, and the condition is easily overlooked. As the disease progresses further, reticular shadows or nodular shadows even nodular nodular shadows may appear within the lung fields, with nodules of 1 to 5mm in size. In the late stage, there are varying sizes of cystic changes, presenting as honeycomb lung, with shrinkage of lung volume, elevation of diaphragm, displacement of interlobar fissures, and easier diagnosis in the late stage, but losing the significance of early diagnosis. About 30% of patients have confirmed interstitial lung fibrosis through lung biopsy, but chest X-ray examination is normal, so X-ray examination is not sensitive enough to alveolar inflammation and lacks specificity. Pulmonary CT or high-resolution CT: It can more finely display the morphological and structural changes of lung tissue and interstitium, and is very valuable for confirming early pulmonary fibrosis and honeycomb lung. The characteristics of CT images include four types of images: nodular shadows, irregular shadows of bronchovascular walls, linear shadows, and lung field concentrations. Nodules can appear at the center of acini, pleura, perivenous area, small veins, and irregular shadows of bronchovascular walls. Similarly, irregular shadows of bronchovascular walls also appear at the center of acini, around bronchial arteries and veins, and small veins. High-resolution CT imaging is significantly better than ordinary chest X-ray films for diagnosing interstitial lung disease, and is very valuable for confirming early pulmonary fibrosis and honeycomb lung. Especially, CT imaging has a unique diagnostic value for ILD that is primarily characterized by peripheral lesions.

　　Three, pulmonary function test

　　This examination is only a functional diagnosis, not a pathological diagnosis. In the early stage, pulmonary function tests can be completely normal, and abnormalities in pulmonary function tests may appear only when the condition progresses. The most significant pulmonary function changes in ILD are abnormal ventilation function and decreased gas exchange function. Ventilation function is mainly characterized by restrictive ventilation disorder, decreased vital capacity, and decreasing residual volume with the progression of the disease, followed by a decrease in total lung capacity. The ratio of forced vital capacity (FVC) to forced expiratory volume in 1 second (FEV1.0) or 1-second rate increases significantly, and if it reaches 90%, it supports the diagnosis of ILD. In the early stage of ILD, there may be small airway dysfunction, with V50 and V25 decreasing, and V50 and V25 increasing after ILD forms fibrosis. In the early stage of ILD, there may also be dysfunction of gas exchange, such as decreased diffusion function (DLCO) in the early stage, and once interstitial changes are found on the chest X-ray, DLCO has decreased below 50%. The correlation between pulmonary function changes and pulmonary lesions is very poor in mild cases and better in severe cases. In cases with severe pulmonary function impairment, pulmonary lesions are definitely severe. Among all pulmonary function tests, the volume-pressure curve test and changes in arterial blood oxygen during exercise are the most sensitive in reflecting the severity of pulmonary fibrosis. Pulmonary function tests are very useful for the early diagnosis and prognosis of ILD, especially the dynamic observation of VC, FEV1.0, DLCO, and other indicators. As for whether pulmonary function tests can judge the efficacy of hormone or immunosuppressive therapy for ILD, there are different opinions, and it is not enough to evaluate the efficacy only by the changes in pulmonary function.

　　Four, pulmonary biopsy

　　Pulmonary biopsy is the best procedure for diagnosing ILD. When the medical history, chest X-ray, pulmonary function test, bronchoalveolar lavage, and biochemical, infectious disease, etc., cannot make an inferential diagnosis, pulmonary biopsy should be performed. Pulmonary biopsy is divided into two types

　　1. The use of fiberoptic bronchoscope for lung biopsy has the advantages of simple operation, high safety, can be routine examination, and is convenient for follow-up. Scholars believe that the lung tissue taken by fiberoptic bronchoscope is too small, (
　　2. Thoracoscopic lung biopsy: Cutting off 2cm×2cm of lung tissue can comprehensively observe the type and severity of alveolitis. Although this method is a traumatic examination method, it is undoubtedly necessary for establishing the diagnosis and avoiding unnecessary various examinations and purposeless treatments. Foreign scholars have reported that in cases where fiberoptic bronchoscope lung biopsy cannot make a definitive diagnosis, 90% can be diagnosed by thoracoscopic biopsy, and it is believed that only thoracoscopic lung biopsy can make a definitive diagnosis of common interstitial pneumonia and desquamative interstitial pneumonia in idiopathic pulmonary fibrosis. In comparison, the development of thoracoscopic lung biopsy in China is very limited, which is the main reason hindering the improvement of diagnostic levels.

　　Elderly patients with interstitial pneumonia should consume high-protein, nutritious, vitamin-rich, mineral-rich, high-calorie, easy-to-digest foods. It is forbidden to eat fried, smoked, grilled, cold, high-salt, and high-fat foods.

　　Currently, there is no special treatment for senile interstitial pneumonia. Idiopathic pulmonary interstitial fibrosis is a progressive disease, and the natural course of the disease is an average of 2-4 years for patients who have not been treated, which can be extended to about 6 years with the use of adrenal cortical steroids. Whether in the early or late stage, treatment should be started immediately to improve the absorption of new alveolar inflammation and to improve some fibrosis, which can also prevent the progression of the disease. The first choice of medication is corticosteroids, followed by immunosuppressants. Adrenal cortical steroids can regulate the inflammatory and immune processes, reduce the content of immune complexes, inhibit the proliferation of alveolar macrophages and the function of T lymphocyte factors, and can absorb and improve the lung X-ray shadows in some patients when used in the stages of alveolar inflammation and cell exudation, resulting in significant improvement in clinical symptoms and lung function.

　　If treatment is started at the stage of advanced widespread interstitial fibrosis and honeycomb lung, clinical symptoms can also be improved to varying degrees, but there is no significant improvement in lung shadows and lung function. The conventional starting dose for chronic type is prednisone 40-60mg/d, taken 3-4 times a day. Once the condition is stable and the X-ray shadow no longer absorbs, the dose can be gradually reduced, with a reduction of 5mg each time after maintaining for 4-8 weeks. When the dose is reduced to 20mg/d, reduce 2.5mg each week, and maintain 10mg/d thereafter, which should not be less than 1 year. If the condition recurs or worsens during the dose reduction process, the dose should be increased again to control the condition, which remains effective. The course of treatment can be extended to two years, and it can be used for life if necessary. It is important to monitor the side effects of the drug and try to achieve the best effect with the smallest dose and the least side effects. When using corticosteroids, attention should be paid to opportunistic infections, the recurrence of tuberculosis, and the necessary combined use of antituberculosis drugs. Long-term use of corticosteroids should be aware of fungal infections. For patients with a severe progression or acute onset, corticosteroid pulse therapy can be used, such as methylprednisolone (methylprednisone) 500mg/d, for 3-5 days, and then changed to oral administration after the condition stabilizes. Finally, the optimal maintenance dose should be determined based on individual differences to prevent recurrence. For those who cannot tolerate corticosteroids due to special reasons, immunosuppressants can be used instead, or the dose of corticosteroids can be reduced while adding immunosuppressants.