Bronchial asthma in children

Introduction to bronchial asthma in children Bronchial asthma (bronchialasthma), referred to as asthma, is one of the common respiratory diseases in pediatrics. It is currently believed that bronchial asthma is a chronic airway inflammatory disease, and many cells play important roles in it, such as lymphocytes, eosinophils, mast cells, etc., accompanied by a significant increase in non-specific airway response. Airway hyperresponsiveness (BHR) is a multifactorial disease with major clinical features. Clinically, it mainly manifests as reversible wheezing and coughing episodes, chest tightness, and difficulty in breathing. These symptoms are often reversible, but they can also cause death. Therefore, the prevention and treatment of asthma should be taken seriously. basic knowledge Sickness ratio: 0.05% Susceptible people: children Mode of infection: non-infectious Complications: pulmonary heart disease, respiratory failure, bronchiectasis, chronic bronchitis

Causes of bronchial asthma in children

Respiratory infections (25%):

(1) Respiratory virus infection: In infants and young children, there are mainly respiratory syncytial virus (RSV), parainfluenza virus, influenza virus and adenovirus, others such as measles virus, mumps virus, enterovirus, poliovirus are occasionally visible. .

(2) Mycoplasma infection: Because the immune system of infants and young children is immature, mycoplasma can cause chronic infection of infants and young children. If not treated properly, it can lead to repeated cough and wheezing.

(3) focal infection of the respiratory tract: chronic sinusitis, rhinitis, otitis media, chronic tonsillitis, is a common chronic focal lesion of the upper respiratory tract in children, which can cause repeated infection on the one hand and nerve reflex on the other hand. Repeated cough and asthma, these lesions need to be treated in a timely manner.

Inhalation of allergens (18%):

In children over 1 year old, respiratory allergies gradually form, such as indoor dust mites, cockroaches, pet fur and outdoor allergens and other allergens, long-term continuous low-intensity allergen inhalation, can induce chronic airway allergic inflammation It causes sensitization of the body and produces chronic atopic inflammation of the airway, promotes the formation of BHR, and increases the time of exposure to allergens, airway inflammation and BHR gradually increase, often develop into childhood asthma, short-term inhalation of high-concentration allergies It can induce acute asthma; such asthma attacks are more abrupt, and most occur in the environment with high concentrations of allergens.

Gastroesophageal reflux (15%):

Due to anatomical structure, there are also iatrogenic factors (such as the application of aminophylline, beta receptor stimulant, etc.) can cause gastroesophageal reflux, especially in infants and young children, it is an important cause of repeated wheezing. First, the clinical manifestations are severe coughing and wheezing during sleep, and there is usually milk or vomiting.

Genetic factors (12%):

Many survey data show that the prevalence of relatives of asthma patients is higher than the prevalence of the population, and the closer the relationship is, the higher the prevalence rate; the more serious the patient's condition, the higher the prevalence of relatives. Currently, the correlation with asthma The genes are not yet fully defined, but studies have shown that multiple loci are associated with allergic diseases, and these genes play an important role in the pathogenesis of asthma.

Other factors (10%):

Inhalation of irritating gases or strenuous exercise, crying, paint, soot, cold air inhalation can be used as non-specific irritants to induce asthma attacks, in which the gas emitted by the paint can trigger a serious and persistent cough and asthma attack, should be avoided, severe Exercise, crying makes the breathing movement faster, the temperature of the respiratory tract is lowered or the osmotic pressure of the fluid in the respiratory tract changes, and an asthma attack is induced.

Pathogenesis

The pathogenesis of asthma is not completely clear. Most people believe that allergic reactions, chronic airway inflammation, increased airway responsiveness, and autonomic dysfunction interact to participate in the pathogenesis of asthma.

Allergic reaction

When the allergen enters the body with allergies, it can stimulate the body's B lymphocytes to synthesize specific IgE through the transmission of macrophages and T lymphocytes, and bind to the high progenitor cells and the high progenitor on the surface of basophils. And the IgE receptor (FcR1), if the allergen re-enters the body, cross-links with IgE on the surface of mast cells and basophils, thereby triggering a series of reactions in the cell, allowing the cell to synthesize and release A variety of active mediators cause smooth muscle contraction, increased mucus secretion, increased vascular permeability and inflammatory cell infiltration. Inflammatory cells can secrete a variety of mediators under the action of mediators, aggravating airway lesions, increasing inflammatory infiltration, and producing asthma. Clinical symptoms, according to the time of asthma after allergen inhalation, can be divided into immediate asthma response (IAR), delayed asthma response (LAR) and bipolar asthma response (OAR), IAR almost inhaled allergens At the same time, the reaction occurs immediately, reaching a peak at 15 to 30 minutes, gradually returning to normal after 2 hours, LA R is about 6 hours, lasting for several days, and the clinical symptoms are heavy, often showing persistent asthma. Now, lung function damage is serious and long-lasting, and the pathogenesis of LAR is more complicated, which is not only related to IgE-mediated mast cell degranulation, but mainly caused by airway inflammation. It is now considered that asthma is a kind of inflammatory cell interaction. Many mediators and cytokines are involved in chronic airway inflammatory diseases.

2. Airway inflammation

Chronic airway inflammation is considered to be the basic pathological change of asthma and the main pathophysiological mechanism of recurrent episodes, regardless of which type of asthma, which stage of asthma, manifested as mast cells, eosinophils and T lymphocytes Cell-based inflammatory cells infiltrate and aggregate in the airways. These cell interactions can secrete dozens of inflammatory mediators and cytokines. These mediators interact with inflammatory cells to form complex networks and interact. And effects, airway inflammation persists, when the body encounters predisposing factors, these inflammatory cells can release a variety of inflammatory mediators and cytokines, causing airway smooth muscle contraction, increased mucus secretion, plasma exudation and mucosal edema, more known Germ cells, including mast cells, eosinophils, neutrophils, epithelial cells, macrophages and endothelial cells, can produce inflammatory mediators. The main mediators are: histamine, prostaglandin (PG), leukotrienes. (LT), platelet activating factor (PAF), eosinophil chemotactic factor (ECF-A), neutrophil chemotactic factor (NCF-A), Major base protein (MBP), eosinophil cationic protein (ECP), endothelin-1 (ET-1), adhesion molecules (AMs), etc. In short, asthmatic airway chronic inflammation is caused by a variety of Inflammatory cells, inflammatory mediators and cytokines are involved, and interactions form a vicious circle, which causes airway inflammation to persist. The relationship is complex and needs further study.

3. Airway hyperresponsiveness (AHR)

It is manifested that the airway has excessive or premature contraction response to various stimulating factors, and it is another important factor in the development of asthma patients. It is generally believed that airway inflammation is one of the important mechanisms leading to airway hyperresponsiveness. Factors such as epithelial damage and regulation of intraepithelial nerve are also involved in the pathogenesis of AHR. When the airway is affected by allergens or other stimuli, the axonal reflex causes parasympathetic nerves due to the release of inflammatory mediators and cytokines by various inflammatory cells. Increased excitability, release of neuropeptides, etc., are related to the pathogenesis of AHR. AHR is a common pathophysiological feature of bronchial asthma patients. However, AHR patients are not all bronchial asthma, such as long-term smoking, exposure to ozone, viral upper respiratory tract. Infection, chronic obstructive pulmonary disease (COPD), etc. can also occur AHR. From a clinical point of view, very mild AHR needs to be diagnosed in combination with clinical manifestations, but moderate to above AHR is almost certainly asthma.

4. Neural mechanisms

Neurological factors are also considered to be an important part of the pathogenesis of asthma. The bronchus is subject to complex autonomic innervation, in addition to cholinergic nerves, adrenergic nerves, and non-adrenergic non-cholinergic (NANC) nervous system, bronchial asthma and The hypofunction of -adrenergic receptors is associated with hyperkinetic vagal tone, and there may be an increase in the reactivity of -adrenergic nerves. NANC can release the neurotransmitters of bronchial smooth muscle, such as vasokinin (VIP). Nitric oxide (NO), as well as mediators that contract bronchial smooth muscle, such as substance P, neurokinin, etc., imbalance between the two, can cause bronchial smooth muscle contraction.

Pediatric bronchial asthma prevention

As long as it can be reasonably standardized for long-term treatment, the vast majority of patients can achieve optimal control of asthma symptoms, reduce recurrence and even no seizures, live, work and learn like normal people, inhalation therapy is to achieve better efficacy and reduce adverse reactions. Important measures, education and management of asthma patients are important measures to improve curative effect, reduce recurrence, and improve patients' quality of life. According to different subjects and specific situations, adopt appropriate, flexible and diverse methods for patients and their families to be willing to accept. They carry out systematic education, improve the initiative of active treatment, improve medication compliance, in order to ensure efficacy, and long-term systematic management of asthma patients, including the following:

1. Avoid and control asthma induced (inducing) factors and reduce recurrence.

2. Develop a medication plan for long-term management of asthma.

3. Develop a treatment plan for the attack period.

4. Regular follow-up care.

5. Enhance physical fitness and enhance disease resistance.

Bronchial complications in children Complications pulmonary heart disease respiratory failure bronchiectasis chronic bronchitis

If a severe acute attack occurs in an asthma patient, it may be fatal if the treatment is not timely. Poorly controlled asthma patients have an impact on daily work and daily life, which can lead to lost work, misunderstanding, resulting in limited activity and exercise, resulting in a decline in quality of life, economic burden and negative impact on family life. . May have pneumothorax, mediastinal emphysema, atelectasis at the onset; long-term recurrent attacks and infections or complicated with chronic bronchitis, emphysema, bronchiectasis, interstitial pneumonia, pulmonary fibrosis and pulmonary heart disease can lead to chronic Complications such as obstructive pulmonary disease, pulmonary heart disease, heart failure, and respiratory failure.

Symptoms of bronchial asthma in children Common symptoms Chest tightness, sitting, breathing, pale, wheezing, dry cough, wheezing, dyspnea, vocal, emotional asthma

The onset of asthma in children may vary from age to age and from different causes. Most asthma in infants and young children is induced by upper respiratory tract infection, and the onset is slower. Children with asthma are mostly induced by inhaled allergens, and the onset is more acute. At the beginning, the main manifestation was irritating dry cough, followed by wheezing symptoms, wheezing and tingling, lighter and no urgency, both lungs only heard wheezing and exhalation time prolonged; severe exhaled dyspnea, irritability Sitting and breathing, and even appear pale, lips, nails and blemishes, and mentally ill, such as the three-concave sign, the intercostal ribs are full, the snoring sounds both drums, the upper liver moves down The heart is narrowed, and there is obvious emphysema. The whole lung can smell and wheezing. If there is more bronchial exudation, wet voice can occur. In severe cases, lung ventilation is very rare. Can disappear, and even can not hear the sound of breathing, asthma is generally relieved by itself or after the drug is given, the disease is recurrent, some patients have a clear seasonality, more nighttime onset, seizure interval, most suffering The symptoms of the child can be completely disappeared. A few children have a nighttime cough and feel uncomfortable with chest tightness.

Pediatric bronchial asthma examination

Blood routine examination

There may be an increase in eosinophils at the time of onset, but most are not obvious; if it is related to viral infection, the white blood cell count is normal or reduced; if the infection is concurrent, the number of white blood cells may increase, and the proportion of classified neutrophils is increased.

2. Sputum examination

Smear showed more eosinophils under the microscope, showing sharp-edged crystals (Charcort-Leyden crystals) formed by eosinophils degeneration, mucus plugs (Curschmann spiral) and transparent asthma beads (laënnec beads), such as combined respiratory tract Bacterial infection, smear gram staining, cell culture and drug sensitivity tests are helpful for the diagnosis and guidance of pathogenic bacteria.

3. Blood gas analysis

There may be hypoxia in severe asthma attacks, PaO2 and SaO2 decrease, PaCO2 may decrease due to hyperventilation, pH value increases, and respiratory alkalosis, such as severe asthma, develops further, airway obstruction is serious, and hypoxia may occur. CO2 retention, PaCO2 rise, showing respiratory acidosis, such as hypoxia, can be combined with metabolic acidosis.

4. Detection of specific allergens

The specific IgE can be determined by radioactive allergen adsorption test (RAST). The serum IgE of patients with allergic asthma can be 2-6 times higher than that of normal people. In the remission period, allergens related to skin allergy test can be judged, but should be prevented. Allergic reaction.

5. Chest X-ray examination

In the early stage of asthma attack, the brightness of both lungs increased and it was over-inflated. There were no obvious abnormalities during the remission period. For example, complicated respiratory infection showed increased lung texture and inflammatory infiltrates, and attention should be paid to atelectasis, pneumothorax or mediastinum. The presence of complications such as emphysema.

6. Pulmonary function test

Most of the lung ventilation function in the remission period is in the normal range. In the asthma attack, due to the limited expiratory flow rate, the first second forced expiratory volume (FEV1), one second rate (FEV1/FVC%), and the maximum expiratory mid-flow rate (MMER), the maximum expiratory flow (MEF50% and MEF75%) and peak expiratory flow (PEFR) were reduced when exhaled 50% and 75% of vital capacity, and the useful capacity was reduced, the residual volume increased, functional residual capacity and lung The total amount increases, and the residual gas accounts for a percentage of the total lung volume, which can be gradually restored after treatment.

7. Other

CT or MRI or fiberoptic bronchoscopy can be performed as necessary to confirm the diagnosis.

Diagnosis and diagnosis of bronchial asthma in children

diagnosis

1. Characteristics of infant asthma:

(1) Coughing is obvious during the day or at night, and it is aggravated after exercise. (2) Pathologically, the mucosa is swollen, the secretion is hyperactive, and the wheezing tone is low. (3) The response to corticosteroids is relatively poor. (4) susceptible to respiratory infections.

2. Characteristics of childhood asthma:

(1) Respiratory allergies gradually appear after 2 years of age. (2) The onset season is related to the type of allergen. (3) There is obvious smooth muscle spasm, and the wheezing sound is high. (4) Better response to glucocorticoids.

3. Characteristics of cough variant asthma:

(1) Long-term cough, no wheezing symptoms. (2) Cough is aggravated at night or in the morning and after strenuous exercise. (3) Antibiotic treatment is ineffective. (4) bronchodilators and glucocorticoids have special effects. (5) Some children have respiratory allergies. (6) Some children eventually develop bronchial asthma. Children's bronchial asthma is divided into three types according to age and clinical manifestations: infant asthma, childhood asthma and cough variant asthma.

3. Diagnostic criteria for infant asthma:

(1) Age <3 years old, wheezing 3 times. (2) There is a wheezing sound in the lungs during the attack, and the exhalation is prolonged. (3) There is atopic constitution (eczema, allergic rhinitis). (4) Family history of asthma. (5) Except for other wheezing diseases, the above-mentioned (1), (2), (5) can diagnose asthma in infants and young children; wheezing episodes 2 times, with articles (2) and (5), diagnosed as Suspected asthma or wheezing bronchus, if both (3) and/or (4) are present, a therapeutic diagnosis may be considered.

4. Diagnostic criteria for childhood asthma:

(1) Age > 3 years old, wheezing recurrent. (2) There are wheezing sounds in both lungs during the attack, and exhalation is prolonged. (3) bronchodilator has obvious curative effect. (4) Wheezing, chest tightness and coughing, among other reasons. (5) For patients with suspected asthma in all ages and wheezing in the lungs, any of the following bronchodilation tests may be performed: aerosol inhalation with an aerosol or solution of a 2 receptor agonist; 1 subcutaneous injection of adrenaline 0.01ml / kg, the maximum amount is not more than 0.3ml / time, after 15min, observe whether there is obvious effect.

5. Cough variant asthma diagnostic criteria:

(1) Cough persists or recurrent (night, morning, exercise, spasm, no infection). (2) The treatment of tracheal dilator is effective (must be standard). (3) The skin allergen test is positive, with a history of allergies or family history. (4) The airway is highly reactive and the bronchial provocation test is positive. (5) Excluding other causes of chronic cough.

Differential diagnosis

Because the clinical manifestations of asthma are not specific to asthma, it is necessary to eliminate wheezing, chest tightness and cough caused by other diseases while establishing a diagnosis.

Cardiogenic asthma

Cardiac asthma is common in left heart failure, and the symptoms at the time of onset are similar to those of asthma, but heart disease asthma has hypertension, acute nephritis complicated with severe circulatory congestion, coronary atherosclerotic heart disease, rheumatic heart disease and biceps History and signs of stenosis, often coughing out pink foam sputum, both lungs can smell a wide range of blisters and wheezing sounds, the left heart is enlarged, the heart rate is increased, the apex can be heard, the chest X-ray examination It can be seen that the heart enlarges, the pulmonary congestion sign, the heart B-ultrasound and the cardiac function test are helpful for identification. If it is difficult to identify the nebulizable selective 2 agonist or the small dose of aminophylline to relieve the symptoms, further examination is prohibited. Adrenaline or morphine to avoid danger.

2. Endotracheal lesions

Tracheal tumors, endometrial tuberculosis and foreign body lesions, causing obstruction of the trachea, can cause symptoms and signs similar to asthma, by raising awareness, timely lung volume volume curve, tracheal tomography or fiberoptic bronchoscopy, usually Can confirm the diagnosis.

3. Tracheal foreign body

See tracheobronchial foreign body.

4. Wheezing chronic bronchitis

In fact, chronic bronchitis with asthma, more common in the elderly, with a history of chronic cough, wheezing for many years, there is a period of aggravation, signs of emphysema, both lungs can be heard and blisters.

5. Bronchial lung cancer

Central lung cancer causes bronchoconstriction or infection or carcinoid syndrome, wheezing or asthma-like dyspnea may occur, the lungs may smell and wheezing, but the dyspnea and wheezing symptoms of lung cancer are progressively worse, often There is no incentive, cough can have blood stasis, cancer cells can be found in the sputum, chest X-ray, CT or MRI or fiberoptic bronchoscopy can often confirm the diagnosis.

6. Allergic lung infiltration

Found in tropical eosinophilia, pulmonary eosinophilic infiltration, multi-source allergic alveolitis, etc., the cause of the disease is parasites, protozoa, pollen, chemicals, occupational dust, etc., more contact history The symptoms are mild, and there may be systemic symptoms such as fever. Chest X-ray examination can be seen in multiple cases. The light and thin patches infiltrating the shadows can disappear or reappear on their own. The lung biopsy also helps to identify.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.