Bronchial asthma in children

Bronchial asthma is a chronic allergic inflammatory disease of the airways involving many cells and cellular elements. Chronic inflammation causes bronchial hyperreactivity, which leads to repeated episodes of wheezing, shortness of breath, chest tightness, and cough, especially at night or in the early morning. These episodes are usually accompanied by diffuse, variable airflow obstruction, which is reversible spontaneously or with treatment.

ICD-10 codes

• J45.0 Asthma with predominantly allergic component.
• J45.1 Non-allergic asthma.
• J45.9 Asthma, unspecified.
• J46 Asthmatic status [status asthmaticus].

Episodes of severe exacerbation of bronchial asthma lasting more than 24 hours, traditionally defined as asthmatic status (status asthmaticus), are designated in modern respiratory medicine guidelines by the terms: acute severe asthma, life threatening asthma, and near-fatal asthma. All definitions have a single meaning - unusual severity and resistance to conventional bronchodilator treatment, and not just the duration of the attack.

Epidemiology of bronchial asthma

The prevalence of bronchial asthma in children varies in different countries and populations, but it occupies a leading place among chronic respiratory diseases. The results of large epidemiological studies indicate that timely diagnosis of bronchial asthma is delayed, for example, the duration of the period between the first symptoms of the disease and the diagnosis exceeds 4 years on average. This situation may be due primarily to the lack of knowledge of the clear criteria for diagnosing bronchial asthma by practicing doctors, the reluctance to register the disease due to fear of worsening the reporting indicators, the negative attitude of the child's parents to this diagnosis, etc.

According to DB Coultas and JM Saniet (1993), the prevalence of asthma varies in the population depending on age and gender characteristics. It has been established that at an early age, boys are more likely to get sick than girls (6% compared to 3.7%), but during puberty the frequency of the disease is the same in both sexes.

A higher prevalence of bronchial asthma in children is typical for ecologically unfavorable industrial areas of cities. Bronchial asthma is registered more often among city dwellers than among villagers (7.1 and 5.7%, respectively). Studies conducted in different countries have shown a higher prevalence of bronchial asthma in regions with a humid and warm climate and a lower prevalence in high-mountain areas, which is associated with different levels of air saturation with aeroallergens. Despite the many existing hypotheses, none of them fully explains the increase in the frequency of bronchial asthma and other allergic diseases.

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Causes of bronchial asthma in children

Bronchial asthma can be of infectious-allergic and allergic origin. In children, the infectious-allergic form is more common. Among the antigenic factors, the main role is played by food allergens, animal hair, house dust, plant pollen, medications, and serums. Allergens implement a broncho-obstructive effect by immune mechanisms. An allergen, combining with antibodies fixed on the mast cell membrane (mainly IgE), forms an immune complex. Immune complexes activate membrane enzymes of mast cells, their permeability increases, anaphylaxis mediators (histamine, serotonin, etc.) are released, which implement the triad of bronchial obstruction syndrome: edema, hypercapnia, and bronchospasm.

Causes of bronchial asthma

Symptoms of bronchial asthma in children

Bronchial asthma is characterized by irritability, loss of appetite, sweating, hyperemia of the sclera, thirst and polyuria, and shallow sleep. The main symptoms are coughing, asthma attacks (usually at night), and difficulty exhaling. All accessory muscles participate in the act of breathing, chest excursion is sharply reduced, and wheezing can be heard from a distance. The face turns blue, the lips swell, the eyelids swell, and the child sits up, leaning on his elbows. As the attack progresses, hypercapnia increases. The development of asthmatic status is most dangerous.

Status asthmaticus is a prolonged attack of bronchial asthma that is not relieved by a single administration of bronchodilators. AS is based on the refractoriness of beta2-adrenoreceptors.

Symptoms of bronchial asthma

Classification of bronchial asthma

By origin:

• infectious-allergic,
• allergic.

By type:

• typical,
• atypical.

By severity:

• light,
• medium-heavy,
• heavy.

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Diagnosis of bronchial asthma

During an attack, blood tests reveal leukopenia, thrombocytopenia, and increased ESR. Most often, the diagnosis is based on the clinical picture. Sometimes the presence of moist rales on inhalation and exhalation allows one to mistakenly suspect small-focal pneumonia. Differential diagnostics are carried out with the following diseases:

• vocal cord dysfunction,
• bronchiolitis,
• aspiration of foreign bodies,
• cystic fibrosis,
• tracheo- or bronchomalacia,
• bronchopulmonary dysplasia,
• bronchiolitis obliterans,
• stenosis of the airways due to hemangiomas or other tumors.

Diagnosis of bronchial asthma

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Treatment of bronchial asthma

Indications for hospitalization in the intensive care unit:

• Difficulty breathing at rest, forced position, agitation, drowsiness or confusion, bradycardia and dyspnea.
• The presence of loud wheezing sounds.
• Heart rate more than 120-160 beats per minute.
• Lack of rapid and obvious response to bronchodilator.
• No improvement after initiation of glucocorticoid treatment for 2-6 hours.
• Further deterioration of the condition.

Drug treatment of bronchial asthma in children

Drugs for the treatment of bronchial asthma are administered orally, parenterally and by inhalation.

Membrane stabilizing drugs

Cromones

• cromoglycic acid,
• undercromiled

Cromoglycic acid and nedocromil are used to treat mild, intermittent and persistent bronchial asthma. Nedocromil helps reduce the severity and duration of bronchoconstriction.

The therapeutic effect of cromoglycic acid is associated with the ability to prevent the development of the early phase of an allergic response by blocking the release of allergy mediators from mast cells and basophils. Cromoglycic acid reduces the permeability of mucous membranes and reduces bronchial hyperreactivity. The drug is prescribed for mild and moderate forms of bronchial asthma, 1-2 inhalations per day for at least 1.5-2 months. Long-term use of cromoglycic acid provides stable remission.

Nedocromil suppresses both the early and late phases of allergic inflammation by inhibiting the release of histamine, leukotriene C4, prostaglandin B, and chemotactic factors from the cells of the respiratory tract mucosa. It has 6-8 times more pronounced anti-inflammatory activity than cromoglycic acid. Prescribed 2 inhalations 2 times a day, the course of treatment is at least 2 months.

Among the drugs capable of suppressing the release of allergic inflammation mediators and causing blockade of H1 histamine receptors, ketotifen should be noted, which is used mainly in young children. Currently, a new class of anti-asthmatic drugs is being studied - the antileukotriene drugs montelukost and zafirlukast.

Inhaled glucocorticoids

The most effective drugs for asthma control at present. In school-age children, maintenance therapy with inhaled glucocorticoids reduces the frequency of exacerbations and the number of hospitalizations, improves the quality of life, improves the function of external respiration, reduces bronchial hyperreactivity and reduces bronchoconstriction during physical exertion. Inhaled glucocorticoids also have a good effect in preschool children. Inhaled glucocorticoids are the only drugs of basic therapy for children under 3 years of age. In pediatric practice, the following inhaled glucocorticoids are used: beclomethasone, fluticasone, budesonide. The use of inhaled glucocorticoids in a dose of 100-200 mcg / day does not have clinically significant side effects, but the use of high doses (800 mcg / day) leads to inhibition of bone formation and degradation processes. Treatment with inhaled glucocorticoids at doses less than 400 mcg/day is usually not associated with significant suppression of the hypothalamic-pituitary-adrenal system and does not increase the incidence of cataracts.

Preference is given to the inhalation method of administration. Its main advantages are:

• direct entry of drugs into the respiratory tract,
• rapid onset of action,
• reduced systemic bioavailability, which minimizes side effects.

In case of insufficient effectiveness of inhaled glucocorticoids, glucocorticoids are prescribed orally or parenterally. According to the duration of action, glucocorticoids are divided into short-acting (hydrocortisone, prednisolone, methylprednisolone), medium-acting (triamcinolone) and long-acting (betamethasone, dexamethasone) drugs. The effect of short-acting drugs lasts 24-36 hours, medium-acting - 36-48 hours, long-acting - over 48 hours. Bronchodilators.

Beta2-Adrenergic agonists

According to the duration of action, sympathomimetics are divided into short-acting and prolonged-acting drugs. Short-acting beta2-adrenergic agonists (salbutamol, terbutaline, fenoterol, clenbuterol) are used to provide emergency care. Among prolonged-acting beta2-adrenergic agonists, there are two types of drugs:

1. 12-hour forms based on salmeterol hydroxynaphthoic acid salt (seretide),
2. controlled release drugs based on salbutamol sulfate (saltos).

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Methylxanthines

Theophylline improves lung function even in doses below the usually recommended therapeutic range. The pharmacological action of theophyllines is based on inhibition of phosphodiesterase and an increase in the content of cyclic adenosine monophosphate, which has the ability to reduce the contractile activity of the smooth muscles of the bronchi, brain vessels, skin and kidneys. There are short-acting and prolonged-action drugs. Short-acting theophylline (aminophylline) is used to relieve acute attacks of bronchospasm. In severe attacks, aminophylline is used intravenously in a daily dose of 5-10 mg / kg in children under 3 years old and 10-15 mg / kg in children from 3 to 15 years old.

Aminophylline is a prolonged-release drug, administered at a rate of 5-6 mg/kg over 20 minutes (if necessary, the administration can be repeated after 6 hours). The maximum daily dose is 20 mg/kg.

Emergency therapy for bronchial asthma

The drugs of choice for the treatment of acute bronchospasm are fast-acting beta2-adrenergic agonists (salbutamol, fenoterol), aminophylline.

An important place in the treatment of an attack of broncho-obstruction is occupied by intravenous administration of glucocorticoids (1-2 mg/kg of prednisolone), which restore the sensitivity of beta2-adrenergic receptors to adrenergic agents.

If there is no effect, a 0.1% solution of epinephrine is administered (no more than 0.015 mg/kg). The use of small doses of epinephrine is justified by the selective sensitivity of beta2-adrenoreceptors of the bronchi to it and allows one to expect a therapeutic effect with a minimal risk of complications from the cardiovascular system. After stopping the attack, intravenous drip administration of epinephrine is continued at a rate of 0.5-1 mcg/(kg h).

Patients are admitted to the intensive care unit with pronounced signs of respiratory failure. Clinical experience shows that patients tolerate hypercapnia better than hypoxemia.

In recent years, the attitude towards early transfer of patients to artificial ventilation has changed. This is due to the use of strict ventilation conditions, which lead to severe complications. Improved oxygenation is achieved by non-invasive ventilation with pressure support. Inhalation anesthetics have a good effect in relieving asthmatic status; there are reports of successful use of ketamine at a dose of 1-2 mg/kg.

Treatment of bronchial asthma

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Prognosis for bronchial asthma in children

In children with recurrent episodes of wheezing due to acute viral infection, who have no signs of atopy or atopic diseases in the family history, the symptoms usually disappear in preschool age, and bronchial asthma does not develop later, although minimal changes in lung function and bronchial hyperreactivity may persist. If wheezing occurs at an early age (before 2 years) in the absence of other symptoms of familial atopy, the likelihood that it will persist into later life is small.