Allergic bronchitis in children
Introduction
Introduction to allergic bronchitis in children Allergic bronchitis in children is also called allergic cough. In 1972, Gluser first reported the disease and named it variant asthma. Cough variant asthma refers to a specific type of asthma with chronic cough as the primary or only clinical manifestation. In the early stage of asthma, about 5-6% are persistent cough as the main symptom, mostly at night or in the early morning, often irritating cough, which is often misdiagnosed as bronchitis. GINA clearly believes that cough variant asthma is a form of asthma. Its pathophysiological changes are the same as asthma, and it is also a persistent airway inflammatory response and airway hyperresponsiveness. basic knowledge The proportion of illness: 0.006% Susceptible people: good for children Mode of infection: non-infectious Complications: cough
Cause
Causes of allergic bronchitis in children
At present, the pathogenesis of allergic bronchitis in children, most scholars believe that it is consistent with the typical mechanism of asthma, is an airway allergic inflammation. It is only the degree of progression of the disease or the severity of airway inflammation is different.
First, mild airway inflammation
Both cough variant asthma and typical asthma have airway allergic inflammation and airway hyperresponsiveness. The pathogenesis and pathogenesis are very similar, but the severity is different or the stage of disease progression is different. The quality and quantity of environmental allergic and non-allergic stimuli that induce airway inflammation are not consistent, and there are large individual differences in the body due to genetic quality, which leads to different body stimuli for different environments. And produce a reaction that is not exactly the same. Due to the different degrees of pathological changes of different organisms, different body or same body will produce different clinical manifestations at different times and occasions. If the patient develops significant airway inflammation, it can stimulate bronchial smooth muscle spasm, which is characterized by wheezing; when the airway inflammation of asthma is mild or superficial, it may not cause bronchial smooth muscle spasm or mild bronchospasm. Mainly swelling, clinical manifestations of chest tightness, if only stimulate the airway mucosal surface, clinically can only be expressed as irritating dry cough. Therefore, mild airway inflammation may be the most important pathogenesis of cough variant asthma.
Second, the neuro-receptor mechanism
Cough is a self-protection mechanism for the airway mucosa to remove foreign substances or mucus and secretions. Cough receptors include two major categories: A fibers, which are fast-regulating extension receptors, mainly concentrated in carina, and are stimulated by slight touch or inhalation of dust; C fibers, whose distal ends are located in the pharynx, bronchial tree, and alveoli. It mainly reacts to chemical irritants such as captopril, certain inflammatory mediators (such as bradykinin), and is also stimulated by certain mechanical forces. C-fibers contain neuropeptides (such as substance P). The release of A) can in turn enhance the activation of A fibers. After the receptor is stimulated, it passes through the vagus nerve to the medulla cough center, and then through the efferent nerve, the diaphragm, intercostal muscle, and pharynx produce corresponding coughing action. Simosson et al found that there is a similar composition between the reflex arc causing cough and the reflex arc of bronchoconstriction, which consists of epithelial submucosal receptors, afferent nerves, medullary center, efferent nerves and muscles. Airway reactivity Both the increase and the increase in the number of coughs are caused by stimulation of the same receptor. During the onset of asthma, airway smooth muscle spasm or certain virulence factors can stimulate cough reflex receptors or cough receptors in the airway epithelium, cause cough directly through the vagus nerve pathway, or indirectly cause cough reflexes by causing local bronchoconstriction. Mc Fadden pointed out that cough variant asthma is mainly atmospheric stenosis. Because the cough receptors in the airway are extremely rich, cough is the main manifestation, and typical bronchial asthma acts on the airway and acts on the surrounding airway due to inflammation. In addition to coughing, there is still wheezing and difficulty breathing. In asthma patients, due to persistent airway inflammation, the surface of the bronchial epithelium is damaged, and the vagus nerve receptors under the tight junction sites between epithelial cells are exposed and easily irritated. The threshold of excitability is lower than that of normal people, and sensitivity to various stimuli. Increased sexuality can cause intractable cough. Koh et al. conducted different concentrations of acetylcholine bronchial provocation test in children with typical asthma, indicating that the wheezing threshold of children with cough variant asthma is higher than that of the typical asthma group, which may be one of the causes of cough and no asthma.
Prevention
Pediatric allergic bronchitis prevention
Allergens should be identified first for effective prevention. The basic content of prevention involves indoor environment, outdoor environment, working environment, smoking, full-term, birth weight, infection, nutrition and diet.
(1) Indoor environment
Infants and children are most closely related to the indoor environment. They have to stay indoors for a long time, the tightness of modern buildings (better door and window closure and lack of natural ventilation). New building materials and updates to interior furniture (including carpets, mattresses and upholstered furniture) will expose infants to long-term exposure to indoor environment allergens (especially house dust mites) and chemically irritating odors. Studies have shown that increased prevalence of childhood allergies is associated with exposure to allergens, which may equally apply to adults. We should further evaluate whether it is possible to improve the indoor environment as a primary prevention strategy for some babies with susceptible allergic bronchitis. For people with asthma susceptibility, especially for young babies, reducing exposure to house dust mites may be a very effective preventive measure, as house dust mites have been shown to be an important asthma-causing factor.
(2) Smoking
Smoking is a category of indoor environmental pollution. Smoking in pregnant women will increase the risk of chronic bronchitis in their future children. For children, if two or one of their parents smokes, the risk of children suffering from allergic bronchitis increases. Children with atopic qualities are more prominent. The study also showed a positive correlation between the degree of exposure to cigarettes and the development of asthma. Given the impact of smoking on asthma, it is possible to achieve a primary goal of reducing smoking among women, especially during pregnancy and perinatal periods, which will reduce the prevalence of asthma. Studies in adults have found that active smokers have higher total 1gE levels than passive smokers and non-smokers, suggesting that smoking also increases the prevalence of asthma in adults. In some cases, especially for occupational asthma, smoking is likely to make smokers more sensitive to environmental asthmatic factors. Preventing passive smoking and prohibiting smoking in pregnant women will also be an important part of primary prevention of asthma.
(3) Outdoor environment
The outdoor environment around the world is quite different. In some countries, visible pollution is still at a high level, while some visible pollution levels are falling. Invisible pollution (mostly from automobile exhaust) is rising. . The level of nitric oxide in the atmosphere has increased over the past 10 years. Although nitric oxide itself does not directly increase the prevalence of allergic bronchitis, its damage to the respiratory epithelium makes it easier for other antigens to enter the deeper layers of the respiratory tract. In the lungs. A study in different regions of Zimbabwe showed that although the prevalence of allergic bronchitis varies widely between regions, it is still more common in cities, and similar studies show that urbanization and urban centers along the jungle The shift in the prevalence of asthma has also increased, although this urbanization has not only caused air pollution, but also changes in indoor living environment have increased the prevalence of asthma.
(4) Working environment
It has been confirmed that occupational allergic bronchitis can be effectively prevented by primary prevention. The substances in the working environment of some occupations can induce airway sensitization or stimulate the airway to induce occupational allergic bronchitis. Taking timely and effective preventive measures to avoid it can prevent occupational asthma. Studies have shown that patients with atopic traits can significantly increase the risk of occupational asthma if they are exposed to certain high molecular weight allergens in the work environment for a prolonged period of time. As with smoking, some special occupations increase the chances of developing atopic ailments. It is therefore important to have primary prevention through appropriate occupational health measures.
(5) Full-term small sample
A small sample is an unbalanced growing newborn with a gestational age of 38-42 weeks but a birth weight of less than 2,500 grams (such as a small torso). Usually due to malnutrition, anemia or various infectious diseases during pregnancy, the fetus is malnourished, which hinders fetal development. The risk of developing asthma in childhood and adolescence will increase. Although we do not know what the mechanism is, it may involve viral-induced increased airway hyperresponsiveness, and nutritional imbalances may also impair the infant's underlying immune mechanisms. Since the small sample is caused by intrauterine malnutrition, the birth of a small sample caused by immature children and other reasons can be avoided by strengthening the nutrition of the mother and increasing the care of the mother. If circumstances permit, breastfeeding should be encouraged after the birth of the sample.
Complication
Pediatric allergic bronchitis complications Complications cough
Can cause sore throat and cough.
Symptom
Pediatric allergic bronchitis symptoms common symptoms cough, sore throat, itchy throat
Because allergic bronchitis in children with cough as the only symptom, the clinical features are lack of specificity, the rate of misdiagnosis is very high. Therefore, for a chronic recurrent cough should be thought of the possibility of the disease. Since about 50%-80% of children with cough variant asthma develop into typical asthma, about 10-33% of adults with cough variant asthma can develop into typical asthma, and many authors consider cough variant asthma as asthma. Pre-existing performance, therefore early diagnosis and early treatment of cough variant asthma is very important to prevent asthma. Mainly have the following clinical features:
First, the incidence of the population: the incidence of children is high, it has been found that more than 30% of children with dry cough and cough variant asthma. In adults, the age of onset of cough variant asthma is higher than that of typical asthma. About 13% of patients are older than 50 years old, and middle-aged women are more common.
Second, the clinical manifestations: cough may be the only symptom of asthma, mainly long-term intractable dry cough, often induced by inhalation of irritating odor, cold air, exposure to allergens, exercise or upper respiratory tract infection, some patients have no incentives. More intensified at night or in the early hours of the morning. Some patients have a certain seasonality, with more spring and autumn. Most patients have been treated with cough and expectorant drugs and antibiotics for a period of time, almost no effect, and the use of glucocorticoids, anti-allergic drugs, 2 receptor agonists and theophylline can be alleviated.
Third, the history of allergies: patients themselves may have a clear history of allergic diseases, such as allergic rhinitis, eczema and so on. Some patients can be traced back to a family history of allergies.
IV. Signs: Although it may also have bronchospasm, it often occurs in the tiny bronchi of the distal end or transient paralysis, so the wheezing sound is not heard or rarely heard during the physical examination.
Examine
Examination of allergic bronchitis in children
1, airway reactivity increased, mostly light-moderate increase. The test procedure can induce irritating coughs at similar onset.
2, lung function damage between normal people and typical asthma.
3, skin allergen test can be positive.
4. Serum IgE levels increase.
5, some patients may be positive for bronchiectasis test, when there is a positive reaction, it indicates that there is a certain state of paralysis and obstruction in the airway.
6, peripheral blood eosinophil count increased, serum ECP levels increased.
Diagnosis
Diagnosis and diagnosis of allergic bronchitis in children
First, diagnosis
At present, there is no unified diagnostic standard. According to the author's clinical experience, the following items can be considered as reference standards for the diagnosis of cough variant asthma:
(1) Repeated episodes of cough lasting more than 1 month, mainly with dry cough; often worsened at night and/or early morning or after exercise;
(b) Cough is associated with exposure to irritating odours, cold air, exposure to allergens or excessive exercise;
(3) may have a history or family history of allergic rhinitis or other allergic diseases, positive allergen test or increased IgE levels;
(iv) Increased airway reactivity;
(5) Antibiotics or symptomatic treatments are ineffective for more than 2 weeks, and are effective against allergy treatment or bronchodilators;
(vi) Excluding chronic cough caused by other chronic respiratory diseases.
Second, auxiliary diagnostic measures
In the case of patients who only complain of long-term cough (time greater than two weeks), the possibility of cough variant asthma should be considered. Based on detailed medical history, careful physical examination, and summary of clinical features, the following methods can be used to confirm the diagnosis:
(1) If the FEV1 or PEFR measured at the time of the patient's visit is less than 70% of the normal value, the bronchodilator can be inhaled, such as 2% salbutamol 200g. After 15 minutes, the above indicators, such as FEV1 and PEFR improvement rate, are retested. 15%, can diagnose the disease.
(B) If the patient's FEV1 and PEFR 70% of the normal expected value at the time of treatment, the bronchial provocation test can be cautiously carried out. See Chapter 1 for specific practices and diagnostic criteria.
(C) Determination of PEFR day and night changes within 24 hours for three consecutive days is a simple and effective screening method for the diagnosis of such bronchial asthma. If the PEFR mutation rate is 20%, the disease can be diagnosed.
Although the measurement of lung function indicators is an effective means of early detection of such asthma, it has been found that the frequency of day and night cough is not related to the degree of lung function damage.
(D) diagnostic treatment: for patients with clinically suspected cough variant asthma, you can try bronchodilators, including inhaled or oral 2 receptor stimulants, theophylline, such as cough significantly reduced or disappeared, then support cough variant asthma Diagnosis; if the effect is not significant, you can use inhaled corticosteroids or oral prednisone (30 ~ 40mg / day), most cough variant asthma can be significantly relieved within a week, a small number of patients need to be treated for two weeks to be effective.
Third, differential diagnosis
Because cough is a non-specific symptom of many diseases, it is necessary to ask for detailed medical history, comprehensive physical examination, chest X-ray or CT, airway responsiveness measurement, pulmonary function, electrocardiogram, fiberoptic bronchoscopy and some special cases. Check to rule out other diseases that can cause chronic, intractable cough.
Many diseases are associated with cough symptoms, and diseases that need to be differentiated from cough variant asthma include COPD, chronic bronchitis, cough caused by gastroesophageal reflux, recurrent respiratory tract infections (RRTI), typical asthma, and postnasal drip synthesis. Disease (PNDS), endobronchial tuberculosis, and angiotensin-converting enzyme inhibitor-induced cough, which are common causes of chronic cough, and need to be carefully excluded in the diagnosis of cough variant asthma. In addition, chronic heart failure, esophageal hiatal hernia, hypertension, airway inflammation, tumors, foreign bodies, and smoke stimuli, anxiety, etc. can lead to chronic cough.
