At present, most scholars believe that the pathogenesis of cough variant asthma in children is consistent with that of typical asthma, and it is an airway allergic inflammation. Only the progress of the disease is different or the severity of airway inflammation is different.
First, mild airway inflammation.
Both cough variant asthma and typical allergic asthma in children have airway allergic inflammation and airway hyperresponsiveness. The etiology and pathogenesis are very similar, but the severity is different or the progress stage of the disease is different. The quality and quantity of environmental allergic and non-allergic stimuli that induce airway inflammation are not consistent, and there are great individual differences in the body due to genetic constitution. If children have obvious airway inflammation, which can stimulate bronchial smooth muscle spasm, they will show wheezing; If only the surface of airway mucosa is stimulated, it can only be manifested as irritating dry cough clinically. Therefore, mild airway allergic inflammation may be the most important pathogenesis of cough variant asthma.
Second, the nerve-receptor mechanism.
Cough is a self-protection mechanism for airway mucosa to remove foreign bodies or mucus and secretions. Mc Fadden pointed out that cough variant asthma is mainly airway stenosis. Because there are abundant cough receptors in the airway, cough is the main manifestation, while typical bronchial asthma causes wheezing and dyspnea besides cough because inflammation acts on the airway and surrounding airway at the same time. Due to persistent allergic airway inflammation, the bronchial epithelial surface of asthmatic children is damaged, which exposes the vagus nerve terminal receptors under the tight connection between epithelial cells and is easy to be stimulated. Its excitation threshold is lower than that of normal people, and its sensitivity to various stimuli increases, so it can cause intractable cough.
Symptoms, signs and laboratory tests
Because cough is the only symptom of cough variant asthma, its clinical features are lack of specificity and the misdiagnosis rate is high. Therefore, the possibility of chronic recurrent cough should be considered. Because about 50%-80% of children with cough variant asthma can develop typical asthma, and about 10-33% of adults can also develop typical asthma, many doctors regard cough variant asthma as a precursor of asthma, so early diagnosis and early treatment of cough variant asthma are very important to prevent asthma.
Children with cough variant asthma mainly have the following clinical features:
First, the incidence population: the incidence rate of children is high, and it has been found that more than 60% of children's dry cough is related to cough variant asthma. In adults, the onset age of cough variant asthma is higher than that of typical asthma, and about 13% of children are over 50 years old, especially middle-aged women.
Second, clinical manifestations: Cough may be the only symptom of children, mainly long-term intractable dry cough, often induced by inhalation of irritating odor, cold air, contact with allergens, exercise or upper respiratory tract infection. Some children have no motivation. It often intensifies at night or in the early morning. Some children have seasonal attacks, mostly in spring and autumn, and some children are prone to cough variant asthma in winter when upper respiratory tract infections are frequent. The child has been treated with antitussive and expectorant drugs and antibiotics for a period of time, with little effect. However, the application of glucocorticoid, antiallergic drugs, receptor agonists and theophylline or bronchodilators can obviously relieve cough.
Third, allergic history: children with cough variant asthma can have a clear history of allergic diseases, such as allergic rhinitis, infantile eczema or food and drug allergy. Some children can be traced back to genetic allergies with a family history.
Fourth, clinical signs: Cough variant asthma can also have bronchospasm, but it mostly occurs in peripheral bronchioles or transient spasms, so there is often no wheezing during auscultation, so it will also make clinicians ignore allergic cough caused by allergic inflammation, which is also one of the important reasons for misdiagnosis.
Verb (abbreviation of verb) clinical examination
1. Airway reactivity increased, mostly mild to moderate. The experimental process can induce an irritating cough similar to an attack.
2. The damage of lung function is between normal people and typical asthma.
3. The skin allergen test may be positive.
4. The serum IgE level increased.
5. Some children may be positive in bronchiectasis test. When there is a positive reaction, it shows that there is a certain spasm and obstruction in the airway.
6. The number of eosinophils in peripheral blood increased, and the level of serum ECP increased.
Diagnosis of cough variant asthma in children
At present, there is no unified diagnostic standard. According to the clinical experience of most allergy specialists, the following items can be used as reference standards for the diagnosis of cough variant asthma:
(1) Recurrent cough lasts more than 1 month, mainly dry cough; It is often aggravated at night and/or early morning, after an attack or exercise, or after a child cries;
(2) Cough is mostly related to contact with pungent odor, cold air, allergens or excessive exercise;
(3) There may be a history or family history of allergic rhinitis or other allergic diseases, positive allergen test or elevated IgE level;
(4) Increased airway reactivity;
(five) antibiotics or symptomatic treatment is ineffective for more than 2 weeks, but antiallergic treatment or bronchodilator is effective;
(6) Eliminate chronic cough caused by other chronic respiratory diseases.
(7) The possibility of cough variant asthma should be considered in children who only complain of long-term cough (more than two weeks). On the basis of detailed medical history, careful physical examination and summary of clinical characteristics, combined with diagnostic treatment, bronchodilators can be tried for children suspected of cough variant asthma, including inhalation or oral administration of β2 receptor stimulants and theophylline. If cough is obviously relieved or disappeared, it supports the diagnosis of cough variant asthma; If the curative effect is not significant, inhaled corticosteroids can be used instead. Most cough variant asthma symptoms can be obviously relieved within one week, and a few children need treatment for two weeks to take effect.
differential diagnosis
Many diseases are accompanied by cough symptoms. Diseases that need to be differentiated from cough variant asthma include pneumonia, bronchiolitis, upper respiratory tract infection, recurrent respiratory tract infection (RRTI), childhood asthma, cough caused by gastroesophageal reflux, rhinorrhea syndrome (PNDS), endobronchial tuberculosis and so on. These diseases are the common causes of chronic cough, and they need to be carefully excluded when diagnosing cough variant asthma.
Treatment of allergic cough variant asthma in children
1. Cough variant asthma can develop into typical asthma, which seriously affects children's sleep, rest and study. It should be diagnosed early and treated actively. Once the cough variant asthma is diagnosed, antibiotics or antiviral drugs should be stopped and attention should be paid to avoiding contact with allergens. Immunoregulation routinely supplements Kangminyuan antiallergic probiotics. It has been proved that the strains contained in Kangminyuan's anti-allergic probiotics can activate the molecules of intestinal immune cells, and the patent proves that it can promote and strengthen the cellular reaction of Th 1 and reduce the serum IgE antibody of allergic cough children. It is a prospective anti-allergic immunomodulatory method, which is helpful to relieve allergic cough and reduce children's repeated cough. For children with allergic rhinitis and allergic cough variant asthma, the lung function and maximal expiratory flow rate of children with Kangminyuan antiallergic probiotics have been significantly improved, especially for the primary prevention of asthma in children with cough variant asthma, and have the effects of improving allergic symptoms and regulating immunity in children with allergic constitution.
Second, the severe cough attack of cough variant asthma is mainly to eliminate allergic inflammation of the lower respiratory tract, including anti-allergic drugs and inhaled corticosteroids for anti-inflammatory treatment. Specific treatment schemes, such as levocetirizine, desloratadine and mast cell stabilizers, such as nedoromide and cromoglycine, can also achieve good results, but they often need to be used continuously for more than two months. If the cough is severe, bronchodilators can be used in combination if necessary, such as inhaling or taking β2 receptor stimulants or/and taking theophylline drugs orally, so as to relieve the cough symptoms in time and avoid inducing asthma.
Three, for children with repeated allergic cough after drug withdrawal, we should cooperate with routine immune regulation, supplement Kangminyuan anti-allergic probiotics, regulate immune function and adjust allergic constitution. In the treatment of variant asthma in allergic cough, parents should also avoid the misunderstanding of stopping taking medicine as long as they don't cough, so as to systematically control the treatment of variant asthma in allergic cough.
Compared with healthy people, the composition of airway microorganisms in asthmatic patients has changed, and airway hyperresponsiveness is closely related to the instability of airway flora structure. Kangminyuan anti-allergic probiotics can be used to treat allergic asthma in allergic cough, and it is suggested to supplement it according to the course of treatment.