The dry winter is the season of high incidence of respiratory diseases. The most common symptom is cough. Many respiratory diseases can lead to cough, and most people know that excessive cough can easily lead to pneumonia and bronchitis. And there is a cough that is often misdiagnosed. Parents should pay attention!

　　A 5-year-old child had a persistent cough for more than half a year. His cough was dry, with little sputum, and was not accompanied by fever. It often broke out at night or early in the morning, affecting sleep at night, and also aggravated after exercise. He has visited 4 hospitals successively, and the chest and lung examinations were all normal. He was diagnosed as 'upper respiratory tract infection', 'tracheitis', etc. He took a lot of antibacterial and antitussive drugs, but they did not work. After the diagnosis, the child was able to：Cough variant asthma.

　　Cough variant asthma (CVA)，Also known as occult asthma, cough type asthma or atypical asthma, it is a special type of asthma with chronic irritating dry cough as the main or only clinical manifestation, which is common in children.

　　The clinical characteristics and diagnostic criteria of cough type asthma are：

　　◆May have a family history of allergy or a history of allergic diseases in other parts, such as allergic rhinitis, skin allergy, etc；

　　◆Cough occurs continuously or repeatedly for more than a month, some even for two or three years；

　　◆Paroxysmal cough is the main symptom. Most people cough before going to bed at night, when they wake up in the middle of the night, and when they wake up in the morning；

　　◆Mainly dry cough, mostly without sputum or a little foam sputum, without typical wheezing；

　　◆Coughing is often induced by upper respiratory tract infection, inhalation of allergens (such as smoke, dust mites, etc.), inhalation of cold air, strenuous exercise, etc., and worsens late at night or early in the morning。

　　Because there is no typical asthma symptoms such as wheezing and dyspnea, it is often missed or misdiagnosed. However, the condition cannot be improved, and most patients can develop typical asthma after a period of time, with wheezing symptoms. Therefore, children who cough for a long time after catching a cold may hide other problems that cannot be ignored! Medical research has found that cough variant asthma and typical bronchial asthma have similar immunological pathogenesis. The increase in the proportion and number of plasma cell like dendritic cells (pDCs) leads to an increase in the number of immune Th2 cells, resulting in a shift in Th1/Th2 balance.

　　Allergen is the main cause of variant asthma, and it should be avoided to contact children again. Pollen, various mites, fungi and the fur of various pets in daily life are common allergens. Some toys, quilts, pillow towels and carpets in the environment are often places where dust mites gather in large numbers. Keeping the environment clean is of great significance to prevent cough asthma.

　　The treatment principle of cough variant asthma (CVA) is the same as that of typical asthma (CA), which requires long-term inhalation of hormones or bronchodilators. However, it needs to be clear that neither CVA nor CA can be cured by current treatment methods.

　　The treatment principle for patients with asthma in remission stage and chronic asthma should be to prevent or reduce repeated attacks of asthma, protect lung function and improve quality of life. Therefore, on the basis of conventional drug treatment, patients also need to strengthen their own immunity and improve their tolerance to allergens.

　　Clinical studies show that, Salt aerosol therapy It is an effective non drug therapy with adjuvant effect on asthma。

　　The therapeutic principle is：

　　When salt aerosol particles enter the respiratory tract, they form a hyperosmotic state in the local airway, which can reduce and eliminate the edema of mucosal epithelial cells, change the rheology of airway secretions, and make sputum thinner and easier to discharge. Sodium ions in salt aerosols can enhance the permeability of mucosal epithelium, and chloride ions can increase β 2. The excitability of receptors can also accelerate the ciliary movement of respiratory epithelium, which is conducive to the elimination of airway secretions, so that the chronic inflammation of the airway can be reduced or eliminated, the spasm of bronchial smooth muscle can be alleviated, the airway hyperreactivity can be reduced, and the pulmonary function can be improved.

　　From the perspective of immunology, the clinical trial results of salt aerosol therapy show that salt therapy can reduce the level of IL-4 (interleukin 4) in serum and increase IFN- γ (gamma interferon) level, regulating IFN- γ /  The level of IL-4 can correct the deviation of Th1/Th2 cells in the body, inhibit the synthesis of IgE (immune globulin), and adjust the abnormal immune status of asthma patients, thus improving the clinical symptoms.