OVERVIEW
The American Thoracic Society (ATS) and the European Respiratory Society (ERS) jointly published a consensus report on the classification of interstitial lung disease in 2002, and interstitial lung disease is collectively referred to as diffuse substantial lung disease, of which those of unknown cause are referred to as idiopathic interstitial pneumonitis (IIP).IIP is further classified into seven clinicopathologic types, which, in decreasing order of prevalence, are: idiopathic pulmonary fibrosis (IPF), non specific interstitial pneumonia (NSIP), cryptogenic mechanized pneumonia, acute interstitial pneumonia, respiratory bronchiolitis-associated interstitial lung disease, desquamative interstitial pneumonia, and lymphocytic interstitial pneumonia. Nonspecific interstitial pneumonia (NSIP) is a type of idiopathic interstitial pneumonia (IIP). In the past, it was categorized in idiopathic interstitial fibrosis, but because its clinical, pathological, imaging, and pulmonary function changes, especially the therapeutic response to glucocorticoids and the prognosis are significantly different from that of IPF, it has been separated from IPF in recent years as an independent idiopathic interstitial lung disease. Because of the relative lack of specificity of its clinical symptoms and pathologic features, it is often diagnosed as IPF, which is actually two different diseases.
Etiology
The cause of the disease is unknown.
Symptoms
NSIP occurs predominantly in middle-aged and old-aged people, and may occur in children, with an average age of 49 years, slightly more in women than in men, and with an insidious or subacute onset. The main clinical manifestations are progressive dyspnea and cough. Compared with UIP (common interstitial pneumonia), most patients with NSIP have a better response to corticosteroids and a relatively better prognosis. About 1/3 of patients have fever, and pestle and mortar finger is rare, accounting for about 13%.
Bilateral lower lung bursting sounds can be heard on physical examination. Some patients have anemia, elevated white blood cell counts, most have increased blood sedimentation, positive CRP (C-reactive protein) reactions, and a few are positive for ANA (antinuclear antibody) and ds-DNA (double-stranded deoxyribonucleic acid). When the lesions are confined to the lungs and no other disease can be identified as the cause, it is characterized as idiopathic nonspecific interstitial pneumonia (INSIP), while other factors that may be etiologically related, such as connective tissue disorders, inhalation of organic dusts, reactions to certain medications, and the mechanization phase of an acute lung injury, are considered to be NSIP.
Tests
(i) Laboratory tests
Bronchoalveolar lavage fluid (BALF) test is not diagnostic of NSIP, but it can rule out some diseases such as infections, tumors, nodular disease and some occupational lung diseases. Increased neutrophils indicate that NSIP has entered the pulmonary fibrosis stage and the prognosis is poor.BALF test can only help to evaluate the response to treatment and the prognosis.
(ii) Other auxiliary tests
1. Chest X-ray
There are interstitial infiltration shadows distributed evenly in the middle and lower lung fields and subpleura bilaterally, which may appear as ground-glass-like with the progression of the disease, with linear, reticular or nodular shadows, but honeycomb lungs seldom appear, and occasionally they appear in a very small amount. In advanced stages, the lungs may decrease in size.
2. HRCT (High Resolution Computed Tomography)
It is an important means of diagnosing NSIP and has characteristic features.
(1) Frosted glass shadow is a piece of vague infiltrative shadow, and vascular texture can be seen in it, mainly distributed in the middle and lower lung fields and subpleura, which is found in about 80% of the patients, but seldom is the only shadow, and it is mostly symmetrical.
(2) Solid shadows often appear as small pieces of solid lesions, which may be symmetrically distributed, mostly in the two middle and lower lungs and the subpleura.
(3) Reticular and linear shadows with dilatation of fine bronchioles and thickening of the pleura.
(4) Honeycomb changes rarely occur, the incidence of which has been reported to range from 0% to 25.8%, and even if they do occur, they account for a small proportion of the overall lesions. At the same time, thickening of bronchial vascular bundles, traction bronchodilatation, and distortion of lung tissue structure are seen, all of which occur in the fibrosis stage.
3. Lung function
Lung function may be unchanged in the early stages of NSIP, but may change at different stages as the disease progresses. As a result, the lung elastic retraction force increases, lung compliance decreases and lung volume decreases. Airflow velocities are not impaired, resulting in normal or high FEV1/FVC. Gas exchange is impaired due to the destruction of capillaries resulting in a decrease in gas exchange area and thickening of the alveolar septum, resulting in an increase in the diffusion distance and consequently a decrease in diffusion function. In addition V/Q ratio imbalance is an important cause of hypoxemia.Arterial blood gases in patients with NSIP show characteristic hypoxemia with increased alveolar arterial oxygen partial pressure difference (A-a) DO2 and venous blood mixing (physiological shunting). Arterial oxygen partial pressure is decreased and arterial carbon dioxide partial pressure is normal or low. Changes in lung function correlate specifically with the severity of the relationship between pneumocyte infiltration and pulmonary fibrosis.
Diagnosis
It is difficult to make a correct diagnosis based only on clinical symptoms and radiographic imaging. Lung biopsy should be sought to obtain histologic evidence in younger patients with atypical IPF in terms of clinical symptoms and imaging. Fibrilloscopic lung biopsy does not yield enough material to provide a diagnosis. Limited open lung biopsy or transthoracoscopic lung biopsy should be pursued if available. Both types of lung biopsy should be selected for fresh lesions, i.e., biopsies taken from sites where inflammation is evident can maintain the characteristics of the original disease. Generally, 2 to 3 pieces are taken, and each piece is about 1 cm in diameter to observe the whole picture of the tissue. If the biopsy is taken from an area with dense lesions and obvious fibrosis, it is difficult to distinguish it from IPF histologically. Limited open lung biopsy (i.e., small incision lung biopsy) involves an incision of only 5 to 7 cm, with little damage, short operative time, and a high positive rate. Transthoracoscopic lung biopsy does not require chest opening, less injury but requires longer time.
Treatment
The main treatment is glucocorticoid therapy with prednisone, the duration of which is determined by the condition until the disease is cured. Only after further stabilization can the drug be gradually reduced and discontinued for at least 1 year. The majority of patients show significant improvement in clinical symptoms, imaging and pulmonary function after treatment, with some patients experiencing absorption of suprapulmonary shadows, some stabilizing their disease, and a few continuing to deteriorate. The efficacy of treatment is closely related to the stage of the disease. The cellular type is in the early stage of the disease and has an ideal efficacy. Mixed type is in the early stage of the disease and has an ideal efficacy, while mixed type has the second best efficacy. Fibrosis type has entered the advanced stage, because the collagen fibers are no longer responsive to the treatment, the efficacy is poor, to the fibrosis stage whether to add immunosuppressive drugs, such as cyclophosphamide azathioprine, etc., the efficacy of which is not yet conclusive.
Prognosis.
NSIP has a better prognosis than IPF, with an average mortality rate of 16% (0%-29%). 5-year survival rate of 76.2% and 10-year survival rate of 35%, compared with the corresponding 43.8% and 15% for IPF. In particular, treatment with glucocorticoids resulted in improvement or stabilization of the disease, except for the severe fibrotic type.
(I) Precautions for non-specific interstitial pneumonia
1. Ensure sufficient rest
Pay attention to keeping warm, avoiding cold, and preventing various infections. Pay attention to climate change, especially in winter and spring, when the temperature changes drastically, increase or decrease clothing in time to avoid aggravation of the disease by cold.
2. Have a comfortable living environment
The room should be quiet, keep clean and hygienic, the air should be fresh, moist and circulating, avoid smoke, perfume, air freshener and other stimulating factors with strong odor, also avoid inhaling air that is too cold, too dry and too wet.
3. Diet
Generally speaking, the diet must be diversified, reasonably matched, nutritious, appropriate ratio, and suitable for digestion and absorption.
4. Mentally, we should maintain a happy and optimistic mood.
Prevent mental stimulation and mental overstress. This requires you to have an open-minded and cheerful attitude towards life, that is to say, to maintain a happy spirit, we must cultivate the idea of “contentment”, but not the excessive pursuit of fame, fortune and enjoyment to realize the “more than the top is not enough, than the bottom of the reasoning, so that you can feel life and psychological satisfaction. This way, you can feel satisfied with your life and psychology. Maintain a happy spirit, but also to arrange the daily life colorful.
5. Keep away from exogenous allergens
Examples of exogenous allergens include: flowers and plants (especially for pollen allergy); bedding and pillows filled with allergy-inducing items such as feathers or old cotton wool; birds; animals (pets or experimental breeders); wood (red cedar dust, cork processing); sugar processing; mushroom farming; cheese; brewing; exposure to moldy straw; water (hot water pipelines, air conditioners, humidifiers, sanitary baths); and agricultural pesticides or herbicides.
(ii) Diet for non-specific interstitial pneumonia
1. Diet should be light, easily digestible, and mainly fluid or semi-fluid;
2. Eat more fruits and vegetables;
3. Drink more water.
(C) Dietary contraindications for non-specific interstitial pneumonia
1. Avoid spicy, acidic, numbing, spicy, deep-fried foods and foods that are easy to induce asthma such as eggs, fish and shrimp;
2. Do not eat stimulating foods;
3. avoid over-salted food, such as pickles and kimchi.