1.Genetic factors
Asthma is a polygenic genetic disease, with a tendency to gather in families. Studies have shown that children with one parent with asthma are 2-5 times more likely to develop asthma than normal children; children with both parents with asthma are 10 times more likely to develop asthma than normal children. Studies have also found that children with asthma have multiple susceptibility genes, gene polymorphisms and copy number mutations, etc. These studies may help to find a new direction for the prevention and treatment of childhood asthma.
2. Environmental triggers
Allergens associated with childhood asthma vary regionally and with climate, season, room and hygiene. Numerous studies have shown that persistent asthma is often associated with exposure to allergens in the indoor environment. Cockroaches are also one of the dominant allergens associated with asthma in urban homes. Pollen allergy is a trigger for acute asthma exacerbations. And in humid environmental conditions, the greatest risk factor is allergy to Streptomyces spp. fungi. National and international guidelines and studies also mention the effect of smoking on childhood asthma, especially maternal smoking during pregnancy has a significant impact on the development of childhood asthma. Some studies suggest that avoidance measures for adult asthmatics such as stopping smoking, removing from smoky environments and reducing exposure to indoor and outdoor pollutants and irritants can also be tried in children with asthma.
(3) Food allergens
Food allergens are mostly seen in allergy to milk and egg whites. The most important allergic factors in infant eczema are related to milk proteins, with allergic components including casein and beta-lactalbumin. In addition, attention should be paid to other food allergy factors, such as peanuts and other nuts, seafood allergies and other foods.
4.Infection
Asthma attacks in children are sometimes associated with infectious factors, which are mainly related to viral and mycoplasma infections. Some of these pathogenic factors are related to genetic mutations, especially asthma attacks after respiratory syncytial virus and rhinovirus infections, which may be related to genetic polymorphisms of inflammatory factors such as interleukin-13.
5.Exercise
The pathogenesis of exercise-induced asthma (EIA) is different from that of childhood asthma mediated by immunoglobulin IgE. The onset of EIA symptoms is related to the type of exercise. The most common types of sports with EIA are cycling, running, and figure skating. In contrast, sports performed in warm and humid environments, such as swimming, badminton and tennis, are less likely to have EIA.
6.Asthma prediction index
The Asthma Prediction Index (API) is effective in predicting the risk of developing persistent asthma in wheezing children aged <3 y. The API consists of children with ≥4 wheezing episodes in the past 1 year, with 1 major risk factor or 2 minor risk factors.
Among these, the major risk factors included.
① Parental history of asthma ;
(ii) diagnosis of atopic dermatitis by a physician;
(③) There is a basis for inhalation allergen sensitization.
Secondary risk factors included.
(i) evidence of food allergen sensitization;
(ii) peripheral blood eosinophils ≥ 4%;
③ wheezing not related to cold. If the asthma prediction index is positive, standardized treatment of asthma is recommended. Children with a positive index must be re-evaluated periodically (every 3-6 months) to determine the continued need for anti-asthma treatment. 2014 “The Global Initiative for Asthma Control” mentions in its approach to asthma management in children <5 years of age that young children with recurrent wheezing who are API positive are more likely than those who are API negative to develop asthma by 6-13 years of age. The likelihood of developing asthma at 6-13 years of age is 4-6 times higher in API-positive children than in API-negative children.
These high-risk factors have a significant impact on the development of childhood asthma, and they can act individually or, more often, in combination and in interaction. The interaction between genetic and environmental factors is a hot topic of research on the pathogenesis of asthma.
Prevention and treatment strategies for childhood asthma
At present, a series of international guidelines and strategies for the prevention and treatment of asthma have been issued, and different countries have also issued relevant guidelines for their own situations.
1.The goals of asthma treatment in children
①To achieve and maintain symptom control;
②Maintain normal activities, including exercise capacity;
③To bring lung function levels as close to normal as possible;
④Prevent acute asthma attacks;
⑤ Avoid adverse reactions due to asthma medication;
⑥Prevent death caused by asthma.
2.Control principles
Asthma control treatment should be as early as possible. The principles of long-term, continuous, standardized and individualized treatment should be adhered to. Treatment includes.
①Acute exacerbation: rapid symptom relief, such as wheezing and anti-inflammatory treatment;
② Chronic duration and clinical remission: prevent symptom exacerbation and relapse, such as avoiding triggers, anti-inflammatory, reducing airway hyperresponsiveness, preventing airway remodeling, and good self-management. Focus on the combination of pharmacological and non-pharmacological treatments, and the role of non-pharmacological treatments such as asthma prevention and control education, allergen avoidance, and management of psychological problems of children in the long-term management of asthma should not be neglected.
3.Long-term treatment plan
Long-term asthma treatment programs for children aged ≥5 years and <5 years are classified according to age. The long-term treatment program is divided into 5 levels. For children with initial asthma who have not been treated in the past, they should choose the level 2, level 3 or level 4 treatment plan according to the severity grading of the disease. At all levels of treatment, the treatment regimen should be reviewed every l or 3 months and adjusted appropriately according to the control of the disease at the appropriate time.
If asthma is controlled and maintained for at least 3 months, the treatment regimen may be considered for downgrading until the minimum dose to maintain asthma control is determined. If partial control is achieved, escalation of therapy may be considered to achieve control. However, the child’s aspiration technique, adherence to the dosing regimen, allergen avoidance, and other triggers should first be checked before escalating therapy. If not controlled, escalate or step up treatment until control is achieved. In the long-term treatment plan for childhood asthma, in addition to the regular daily use of control therapy medications, relieving medications should be used as needed according to the condition.
4.Acute attack treatment
The treatment should be individualized on the basis of the severity of the acute attack and the response to the initial treatment measures. Children with critical asthma should be placed in a good medical environment with oxygen supply to maintain oxygen saturation above 0.92 for cardiopulmonary monitoring, monitoring blood gas analysis and ventilation function, and sedation should be prohibited for those who are not extubated.
5.Patient education
Although asthma is not yet curable, clinical control of asthma can be achieved through effective prevention and control education and management and the establishment of a partnership between doctors and patients. Asthma prevention and control education is the most essential part to achieve the goal of good asthma control. 2012 International Consensus on Childhood Asthma was published, and the consensus suggests that both children and their parents or guardians should receive education on asthma treatment and work together with asthma health education messengers to optimize the management of asthma. The objective means of evaluation of asthma control is the measurement of pulmonary ventilation function and peak flow rate.
Pulmonary function measurements can be done every 3 months if available, and children aged ≥5 years can be adhered to and recorded daily for peak flow rate measurements. Clinically validated asthma control tools such as the Asthma Control Test for Children and the Asthma Control Questionnaire can be used to assess the level of asthma control and can be used as a supplement to pulmonary function.