Epidemiology
Asthma can occur at any age. 30% of patients have symptoms at 1 year of age and 80-90% of children with asthma have their first symptoms before the age of 4 to 5 years. Most affected children have only occasional episodes as mild to moderate and are relatively easy to manage, while a few have severe refractory asthma with more perennial than seasonal attacks. The relationship between early and late age of onset and prognosis is not well understood.
Most severely affected children with wheezing start in the first year of life, have a history of allergic disease (especially atopic dermatitis, allergic rhinitis), these children with relatives with a history of asthma may have growth retardation (not related to inhaled hormones, as their eventual height can be normal), and chest deformities secondary to chest hyperinflation and abnormal lung function. The prognosis for young children with asthma is generally good.
Long-term studies indicate that 50% of children with asthma disappear within 10 to 20 years of age, but attacks may still occur in adults. If there is asthma occurring between the age of 2 and adolescence, the remission rate is about 50%. About 95% of patients with severe asthma who are hormone-dependent and frequently hospitalized become adults with asthma.
Pathological basis
Asthma is a chronic metabolic inflammatory disease of the airways that involves complex interactions between inflammatory cells and mediators and airway tissues and cells. These interactions lead to edema of the airway wall, increased mucus secretion, acute bronchoconstriction, and also to airway hyperresponsiveness to different stimuli and highly reversible airway obstruction, which can be followed by airway remodeling and irreversible airflow limitation.
Definition of bronchial asthma
Bronchial asthma is a chronic inflammatory disorder of the airways involving a variety of cells (especially eosinophils, mast cells, T lymphocytes, neutrophils and airway epithelial cells) and cellular components. This chronic inflammation leads to airway hyperresponsiveness, causing recurrent episodes of wheezing, shortness of breath, chest tightness, and coughing, which often flare up or worsen at night and/or early in the morning, and are generally characterized by widespread and variable reversible airflow obstruction. Most children can be treated or resolve on their own.
Diagnostic criteria for asthma in infants and children
Wheezing symptoms in infancy are mainly cough, wheezing, shortness of breath, nocturnal awakening, speech discontinuity and feeding difficulties, triggered mostly by respiratory viral infections, exercise, crying, laughing and mood swings. Respiratory viral infections, exposure to environmental allergens, concomitant allergic rhinitis, and gastroesophageal reflux can also cause asthma.
In terms of allergen diagnosis, room dust mites are common in addition to viral infections, followed by inhalation allergens such as molds, cockroaches, and silk. Skin prick tests can also be performed in infants and children, and their positive intensity is weak, but the clinical diagnostic compliance rate is high, while the history of food allergens is important for diagnosis.
Skin atopy is low, and there are false positives, such as food allergy causing wheezing often accompanied by other allergies, such as urticaria, allergic rhinitis, allergic conjunctivitis, and also food allergy to a food allergy when there is a refusal to eat performance. If in vitro testing is available, an enzyme-linked immunosorbent assay can be used to determine allergen-specific IgE in the blood.
The diagnostic criteria for asthma in infants and children aged <3 years are
(1) ≥3 episodes of wheezing;
(2) A predominantly expiratory phase croup is heard in both lungs during the attack, with a prolonged expiratory phase;
(3) Atopic physiology, such as infantile eczema, allergic rhinitis, etc;
(4) History of allergy such as asthma in first-degree relatives;
(5) exclude other wheezing diseases in infancy and childhood.
Asthma can be diagnosed by having (1), (2) and (5) above. If there are only 2 wheezing episodes and (2) and (5) are present, the diagnosis of suspected asthma is made first. If both (3) or (4) are present, therapeutic diagnosis of asthma can be made and a positive diagnosis of asthma can be made.
In children with atypical symptoms who also have croup heard in the lungs, any 1 of the following bronchodilator tests may be used to assist in the diagnosis, as appropriate, and if positive, asthma may be diagnosed.
(1) Rapid-acting β2 agonist solution or aerosol inhalation;
(2) subcutaneous injection of 0.01 ml/kg of 0.1% epinephrine (maximum of 0.3 ml/dose). Within 15-30 minutes after performing any 1 of the above tests, the test is positive if wheezing is significantly relieved and croup is significantly reduced.
Differential diagnosis
In infants and children, wheezing due to extensive airway involvement is present in both asthma and acute respiratory infections, but respiratory symptoms can also be caused by localized airway obstruction, so it is important to think of a differential diagnosis.
(i) Capillary bronchitis
It is mainly caused by respiratory syncytial virus and parainfluenza virus infections, and is prevalent in infants from 2 to 6 months, often in winter and spring, with epidemics reported in Guangxi, Wenzhou, Zhejiang, and Shanxi. Wheezing is the most common symptom of acute respiratory infections, especially viral infections. The first wheezing in infants may be capillary bronchitis, while multiple wheezing at 1 year of age may be asthma, which may help to diagnose if the treatment is effective according to asthma.
(ii) Wheezing bronchitis
Occurring within 3 years of age, the clinical presentation is bronchitis with wheezing, often with fever and wheezing, which disappears with inflammation control, usually without respiratory distress, and lasts about a week. Most of the attacks stop by the age of 4~5 years, and now the general tendency is to diagnose asthma if there are typical expiratory phase wheezing with 3 attacks and except other wheezing causing diseases, such as 2 attacks of wheezing, atopic physique, family history of asthma, and elevated serum IgE, early anti-asthma treatment should be given. Many countries have abolished this name, and our childhood asthma routine includes it in suspected asthma.
(iii) Congenital laryngeal wheeze
Congenital laryngeal wheeze is caused by poor laryngeal development resulting in softening of the laryngeal cartilage, which causes wheezing and dyspnea when the laryngeal tissues sink into the voice box during inspiration. In severe cases, inspiration is difficult and there is a sternal fossa and intercostal depression. The wheezing sometimes disappears in the prone position or when the baby is picked up. The wheezing usually disappears between 6 months and 2 years of age.
(iv) Foreign body aspiration
Sometimes there is no abnormality on chest radiographs, but inspiratory and expiratory fluoroscopy or radiographs should be done. There may be mediastinal oscillation or inconsistency in the transmittance of both lungs due to gas retention on one side. If the X-ray examination is negative and still cannot exclude the foreign body, bronchoscopy can be performed. I have seen an airway foreign body toddler with episodic wheezing in the lungs, but no history of foreign body inhalation, and the wheezing disappeared after negative X-ray examination and bronchoscopy to remove watermelon rind from the bronchial wall. Occasionally, foreign bodies in the esophagus compressing the airway cause wheezing.
(v) Bronchial lymphatic tuberculosis
Bronchial lymphatic tuberculosis can be caused by enlarged lymph nodes compressing the bronchi or by partial or complete obstruction due to erosion and invasion of the bronchial wall by the tuberculous lesion, resulting in paroxysmal spasmodic cough with wheezing, often accompanied by fatigue, low-grade fever, night sweats, and weight loss. PPD, X-ray, sputum TB examination and determination of serum antibodies can be done. Bronchoscopy should be done for airway obstruction caused by suspected endobronchial tuberculosis.
(vi) Cricoid vascular compression
It is a congenital malformation, mostly occurring at the aortic arch, with double aortic arch or with annular vascular malformation. It consists of one anterior and one posterior vessel surrounding the airway and esophagus, which subsequently merge to form the descending aorta. In some cases, the right aortic arch and the left aortic ligament form a ring, and the former compresses the trachea and esophagus.
(vii) Gastroesophageal reflux
Reflux occurs in most infants after feeding, with inflammatory changes in the esophageal mucosa. Reflux can cause reflex tracheal spasm with coughing and wheezing; barium swallow X-ray is feasible, and in recent years, 24-hour PH monitoring of the esophagus has been used to aid in the diagnosis.
(viii) Congenital airway malformation
Such as laryngeal webbing, hemangioma, polyps, etc., congenital airway developmental abnormalities cause laryngeal narrowing, if the larynx is completely obstructed after birth can die due to asphyxia. If the larynx is partially obstructed, the cry is weakened, hoarseness or loss of voice, and there is difficulty in breathing and cyanosis during inspiration and expiration. Physical examination shows no local inflammation, and laryngoscopy shows laryngeal webbing; for polyps and hemangiomas, X-ray and bronchoscopy can be helpful for diagnosis.
Drug treatment
Asthma is a chronic inflammatory disease and anti-inflammatory therapy should be applied as early as possible. Inhaled hormone is the drug of choice to control asthma. The importance of early anti-inflammatory therapy in patients with moderate to severe asthma should be emphasized in treatment.
Although there may be overtreatment in young children with asthma, effective use of antiallergic medications and bronchodilators is more effective than antibiotics in shortening or reducing wheezing episodes, and health care professionals should be encouraged to use the term “asthma” rather than other terms when describing recurrent virus-related wheezing in infancy and early childhood. terminology.
It is important to rule out other wheezing disorders before and after treatment for asthma, and the development of recurrent wheezing despite regular treatment for asthma must be carefully examined in terms of medication use, compliance by relatives and the child, and further exclusion of other causes of wheezing.
(i) Glucocorticoids
Since inhaled hormones are the most effective drugs for suppressing submucosal inflammation in the airways and can increase the bronchodilator effect of β2 agonists without the side effects of systemic hormone application in appropriate doses, their status in asthma treatment is highly valued and the scope of application is significantly wider than before.
In recent years, Pedersen in Denmark has observed the inhalation of glucocorticoids in children with early asthma and concluded that early inhalation of corticosteroids can prevent asthma from developing into irreversible airway obstruction and has no effect on the development of children, and emphasized that the inhalation of larger doses at the beginning of treatment can achieve the best possible control of asthma, and oral hormones can be applied for a short period of time in severe cases. The side effects of under-treatment are more serious than those of glucagon.
Inhalation of peclosone propionate (BDP) at a dose of 200-400 μg/day is safe for young children, and up to 600-800 μg/day for children with severe disease. Adjust the dosage as appropriate when applying budesonide (BUD), and halve the dosage when applying fluticasone. Once the disease is controlled and stabilized, the dose should be reduced to the regular inhalation dose.
Younger children should inhale BDP or BUD in combination with a masked fog canister at a dose of 200 to 1000 μg/day when applying quantitative aerosol hormone inhalation. For young children with asthma who have difficulty inhaling quantitative aerosol or who are severely ill, budesonide suspension, 0.5 to 1 mg/dose can be used. It can be combined with β2 agonist and/or anticholinergic solution for nebulized inhalation once or twice a day.
Once the disease is controlled, then the asthma medication can be discontinued. Budesonide suspension inhalation may be given for several weeks to months or longer, or aerosol inhalation may be used instead as appropriate. The course of hormone inhalation is long, more than 1 year, but now there are also advocates of mild and moderate patients with a course of up to 3 to 5 years. After inhalation of hormones, the mouth should be rinsed to reduce the occurrence of oral thrush and hoarseness.
(II) Bronchodilators
1.β2 receptor agonist
Short-acting β2 agonists are the most effective bronchodilators (salbutamol, terbutaline), and are now advocated for on-demand inhalation when symptoms are present, but when symptoms are not fully controlled, they are used as supplemental therapy to hormone inhalation, but the dose used is <3 to 4 times a day, 2 seizures each time (100 μg/seizure), but when the conventional dose cannot be controlled, the dose is generally no longer increased, but emphasis is placed on finding out whether there is an allergen exposure, except for poor mastery of inhalation techniques, or insufficient amount of airway anti-inflammatory therapy, or inappropriate choice of drug dosage form, whether accompanied by allergic rhinitis or nocturnal asthma attack symptoms are ignored, etc., should be added to the above situation with antihistamines, long-acting controlled-release theophylline or long-acting β2 agonists orally or increased hormone inhalation.
2.Theophylline
Theophylline has a direct relaxing effect on smooth muscle, and can inhibit phosphodiesterase to prevent the breakdown of cAMP in airway smooth muscle, so that smooth muscle tone is reduced and the airway is dilated. Theophylline is now considered to have some anti-inflammatory effect and is favored for asthma patients with nocturnal attacks. Controlled-release theophylline is commonly used at a dose of 6-8 mg/kg.day, divided into 2 oral doses. In severe asthma attacks, a loading dose of theophylline can be given intravenously, 4-5mg/kg. times, input in about 20 minutes, and the first dose is halved for those <2 years old or who have used theophylline within 6 hours.
3.Anti-cholinergic drugs
ipratropium bromide has a strong relaxing effect on airway smooth muscle, but its effect on cardiovascular system is weak, and the peak time is about 30-60 minutes. It has a preventive effect on asthma, and its action site is mainly in the large and middle airways, while β2 receptor stimulant mainly acts in the small airways. Therefore, the two drugs have synergistic effects and are often used clinically as adjuvants of β2 agonists. Love asthma aerosol dose: 20μg / seize, 1 ~ 2 seize / time, 3 ~ 4 times / day.
4, magnesium sulfate
Magnesium is one of the most abundant ions in the human body, about the mechanism of magnesium ion expansion bronchus, so far not completely clear, it is generally believed that magnesium can regulate the activity of a variety of enzymes, can activate adenylyl cyclase, activate the function of low adrenergic beta receptors, and reduce the tension of bronchial smooth muscle, so that bronchial expansion and improve ventilation. Children’s dosage is 0.025g/kg.times (25% magnesium sulfate 0.1ml/kg.times) plus 10% glucose solution 20ml, intravenous drip in 20 minutes, 1 to 3 times a day, can be used continuously for 2 to 3 days, can obtain a certain bronchial antispasmodic and sedative effect.
(iii) Allergic mediator release inhibitors
1.Leukotriene receptor modulators
Such as montelukast sodium, zalust. Can selectively inhibit the activity of leukotriene polypeptide in airway smooth muscle, and effectively prevent and inhibit leukotrienes caused by increased vascular permeability, airway eosinophil infiltration and bronchospasm, can reduce the airway caused by allergen stimulation of cellular and non-cellular inflammatory substances, can inhibit airway hyperreactivity.
It inhibits both rapid- and late-phase inflammatory reactions caused by stimuli such as sulfur dioxide, exercise and cold air, and various allergens such as pollen and hair dander. It is mainly used for allergen (allergen)-induced mild asthma, exercise-induced airway spasm and aspirin-induced asthma. Combined with inhaled glucocorticosteroids in the treatment of children with moderate or severe persistent asthma, it can reduce the dose of glucocorticosteroids and improve the efficacy of inhaled glucocorticosteroids. Zalust is indicated for long-term prophylactic treatment of asthma in children over 12 years of age. Montelukast can be used in children aged 2 to 5 years, 4 mg orally once a day.
2.Antihistamines
(1) Sodium cromoglycate (SCG): It is an anti-allergic drug that inhibits the release of mediators such as mast cells, blocks late reactions and suppresses non-specific bronchial hyperresponsiveness. It can prevent type I allergic reactions and exercise-induced asthma with few side effects when given before an asthma attack, and can be used in children with mild to moderate asthma as sodium cromoglycate. 2mg, 5mg/grip aerosol (2 grips each time) is inhaled 3-4 times a day.
(2) Loratadine, cetirizine, etc.: with anti-allergic effect, the effect of asthma is weaker, but can be used in children with asthma with allergic rhinitis, and some studies have found that the application in infants and children with recurrent respiratory infections or allergy to mites and Artemisia pollen can reduce the occurrence of asthma.
(iv) Other drugs
1. Immunomodulators
Immunomodulators, such as thymidine, BCG ribonucleic acid, Astragalus, Sophora, etc., can be added as appropriate for those with wheezing induced by recurrent respiratory tract infections.
2.Chinese medicine
Treat with evidence during acute attack. Preventive treatment during the remission period by strengthening the spleen and tonifying the kidney to support the righteousness.
(v) Antibiotic application
Antibiotics are not necessary for asthma attacks caused by general allergic factors; if there is bacterial infection, appropriate antibiotics can be used according to the infection.
Long-term treatment plan for asthma in infants and children
Asthma is a chronic disease that requires long-term management and a stepwise treatment regimen is used in its treatment. Infants and children should be treated with a dose of aerosol inhalation assisted by a storage canister with a face mask.
Management education for infants and children with asthma
Asthma is a chronic inflammatory condition of the airways, often with acute exacerbations, and treatment is aimed at standardizing medication and controlling or reducing exacerbations, which is also fundamental to asthma treatment. This requires not only the proper guidance of healthcare professionals, but also the active cooperation of patients. However, it is common in clinical practice that many patients do not have attacks after remission or for a period of time, and parents mistakenly believe that they are cured, or worry about the side effects of medication and stop the medication on their own, resulting in recurrent asthma attacks. Therefore, it is very important to educate children with asthma and their parents on how to self-manage, adhere to the medication and use it correctly for effective asthma control.
To this end, the following aspects should be noted.
(i) Strengthening publicity and education
Through various means such as lectures on asthma, videos, knowledge competitions, television, distribution of promotional materials or books on science, etc., children and their parents should be educated about asthma and have their questions answered so that they can have a more comprehensive and correct understanding of asthma as a chronic disease, such as the causes, severity of the disease, hazards, prognosis and the benefits of adhering to treatment.
To eliminate the parents’ misconceptions about asthma, to eliminate the worries about the side effects of inhaled glucocorticoids, to enhance the confidence in treatment, to improve their conscientiousness to attend medical appointments frequently and to adhere to long-term treatment, so as to reduce the occurrence of severe asthma, to ensure a normal life, to reduce the burden on society and families, to reduce deaths caused by asthma, and to enable the majority of asthma patients to have a colorful life.
(ii) Develop individualized treatment plans
Provide the best treatment plan to the parents of the children so that they can understand the various medications and teach them to control their own asthma, so that the children can receive appropriate emergency treatment in case of asthma attacks and can prevent severe asthma attacks.
(3) Instruct children to master the correct technique of inhalation
Inhalation therapy is a new drug delivery measure, and many children are not used to using it and have poor mastery of the inhalation technique, which affects the therapeutic effect. Therefore, at the first visit of the child, we should patiently instruct the child and parents how to use and correct them at future visits. Many patients with poor efficacy after inhalation of drugs are caused by incorrect inhalation methods.
(4) Instruct parents to do a good job of home management and monitoring
Asthma attacks are often recurrent, and even if inhalation therapy is adhered to, attacks may still occur in some cases. Therefore, parents should be informed of the causes and aura of asthma attacks, so that they can seek timely medical consultation or strengthen treatment with medication to control the disease, reduce severe asthma attacks and avoid hospitalization. Also pay attention to improving the living and working environment to avoid exposure to allergens or triggers.
(5) Establish a good doctor-patient relationship with parents of children with asthma
Respecting and understanding the child and maintaining frequent contact with the parents are conducive to effective management of the child and monitoring of the condition, as well as improving his or her adherence to long-term treatment.
Care of infants and children with asthma
Care during acute exacerbations should be noted that infants and young children have narrow airways and very small changes such as minor obstruction, sputum mucus plug and bronchospasm can easily cause an increase in airway resistance, so the condition should be closely observed. The onset of wheezing in infants and young children is often associated with viral infections, which increase airway inflammation, damage airway epithelium, impaired β2-adrenergic receptor function, and increase airway inflammation and reactivity, so attention should be paid to isolation from patients with respiratory viral infections in the environment at regular intervals, while outdoor activities should be strengthened to enhance physical fitness, and attention should be paid to nutrition and vitamin supplementation.