Asthma

Introduction to asthma Bronchial asthma (bronchialasthma, asthma) is a chronic airway inflammation involving a variety of cells, especially mast cells, eosinophils, and T lymphocytes. In susceptible individuals, this inflammation can cause recurrent wheezing, shortness of breath, Symptoms such as chest tightness and/or cough occur mostly at night and/or in the early hours of the morning, and the airway is more reactive toward multiple stimuli. However, the symptoms can be relieved by themselves or by treatment. In the past ten years, the prevalence and mortality of asthma in the United States, Britain, Australia, New Zealand and other countries have increased. About 100 million asthma patients in the world have become a major chronic disease that seriously threatens public health. The prevalence rate is about 1%, and children can reach 3%. It is estimated that there are more than 10 million asthma patients in the country. basic knowledge Sickness ratio: 0.30% Susceptible people: no specific population Mode of infection: non-infectious Complications: sudden death, arrhythmia, pneumothorax

Cause of asthma

Asthma is a disease that occurs through the interaction of environmental factors based on genetic susceptibility. Genetic susceptibility involves multiple genes and their interactions, and the environmental factors that cause disease are also diverse.

Genetic factors (20%):

Genetics is the main host factor. The absence of a known gene in two or more study populations suggests that intergenic interactions may be more important and reaffirm the polygenic genetics of asthma. In addition, the targets of drug action, such as 2 receptors, glucocorticoid receptors and other related genes are also research hotspots. The abnormalities of these genes may not only be related to the pathogenesis, but also related to the therapeutic effect.

Obesity (15%):

Obesity is an independent risk factor for asthma, especially in women. Obese asthma patients are more difficult to treat. Possible mechanisms: 1. Change the mechanical properties of the respiratory system. 2, adipose tissue release IL-6, TNF-, eotaxin, estrogen and other inflammatory factors, so that the immune function as a whole promotes a pro-inflammatory tendency. 3. The occurrence of obesity is also a concentrated reflection of some defects in the body in genetics, development, endocrine, and neuromodulation. These defects may also be the cause of asthma.

Allergens (10%):

1. Inhalation of allergens is the cause of asthma, and this view has been widely accepted. Dermatophagoides sp. is the most common inhaled allergen that induces asthma attacks. Pollen, ragweed, and fungal spore-induced asthma are often seasonal. When a storm occurs, a large amount of pollen is often raised, which may cause many asthma patients to attack at the same time, called "thunderstorm asthma". Allergens that are present in the environment all the year round can cause chronic persistent symptoms in patients. Most of these allergens are derived from household pet dander, mites, dust, and the like.

2. The relationship between allergens and asthma is complicated, and may be affected by various factors such as the type of allergen, the dose of exposure, the time of exposure, the age of the host at the time of exposure, and the genetic characteristics of the host. Sometimes, early exposure to allergies It can induce immune tolerance and has a protective effect. In addition, strict avoidance of exposure to allergens does not reduce the risk of developing asthma.

Smoking (15%):

1. Exposure to smoking smoke in the uterus and after birth can increase the risk of asthma-like symptoms in children.

2, smoking has a serious negative impact on asthma patients: can lead to frequent attacks of asthma, accelerated decline in lung function, more serious illness, increased hospitalization rate, weaken the role of corticosteroids, higher mortality. There is a neutrophil-predominant inflammatory response in the airways of smoking asthma patients, which is different from general asthma.

Air pollution (10%):

1, air pollutants, such as sulfur dioxide, ozone, can induce asthma attacks.

2. The impact of air pollutants on the prevalence of asthma remains undetermined. Cities with serious traffic pollution have not found an increase in the prevalence of asthma.

Asthma prevention

1. Avoid clear contact with allergens. For example, if indoor dust or sputum induces asthma, keep indoors clean, dry and bedding, and always open windows to keep the indoor air fresh.

2, it is not appropriate to keep cats, dogs and other small animals indoors.

3, usually should pay attention to the child's physical exercise, such as the usual cold water bath, dry towel body and other skin exercises, so that the nervous state of the lungs, trachea, bronchial vagus nerves are alleviated.

4, strengthen nutrition, avoid mental stimulation, avoid colds and excessive fatigue also play an important role in the prevention of asthma attacks.

Asthma complications Complications sudden death arrhythmia pneumothorax

1, dying

Sudden death is the most serious complication of bronchial asthma, because it often has no obvious aura symptoms. Once it happens suddenly, it is often too late to save and die. The important reasons for sudden death of asthma can be summarized as:

(1) Specific hypersensitivity reaction: Due to the high sensitivity state of the airway, specific or non-specific stimulation, especially when performing airway reactivity measurement, can cause severe laryngeal, tracheal edema and extensive bronchospasm, causing obstruction of the trachea Or induce severe arrhythmia or even sudden cardiac arrest and death.

(2) Locked lung: The side effects of bronchial or isoproterenol can be blocked by extensive sputum plugs, which are not only unable to excite beta receptors but also because of the metabolite 3-methoxyisoproterenol, which is metabolized by the drug. It acts as a beta blocker, causing bronchial smooth muscle spasm and ventilating block.

(3) fatal arrhythmia: can be caused by severe hypoxia, water, electrolyte and acid-base imbalance, or by improper use of drugs, such as digitalis in the treatment of heart failure, beta-agonist stimulant, anaerobic tea Alkali, etc., if intravenous aminophylline, blood concentration > 30mg / L, can induce tachyarrhythmia.

(4) Outbreak of bronchial asthma: It is often too late to die with medication, and the mechanism is unknown.

(5) Improper application of anesthetics or sedatives: anesthetics can cause respiratory depression or even sudden arrest. Some sedatives also have significant inhibitory effects on the respiratory center, such as barbiturates, chlorpromazines, and sudden death. Artificial airways should be established immediately, artificial ventilation should be carried out, and important organs such as the heart and brain should be effectively treated accordingly.

2, lower respiratory tract and lung infection

According to statistics, about half of asthma is induced by upper respiratory tract infection, and thus the immune function of the respiratory tract is disturbed, and it is easy to secondary to lower respiratory tract and lung infection. Therefore, efforts should be made to improve the immune function of asthma patients and maintain airway patency. Clear airway endocrine, keep the room clean, prevent colds, and reduce infection; once there is a sign of infection, appropriate antibiotics should be used according to the bacteria and drug sensitivity.

3, water and electrolyte and acid-base imbalance

Due to asthma attacks, hypoxia, inadequate feeding, dehydration, heart, liver, especially respiratory and renal insufficiency, often accompanied by water, electrolytes and acid-base imbalance, these are important factors affecting the efficacy and prognosis of asthma, we must strive to maintain water, Electrolyte and acid-base balance, daily monitoring of electrolytes and arterial blood gas analysis every day, timely detection of abnormalities, timely treatment.

4, pneumothorax and mediastinal emphysema

As the gas is trapped in the alveoli during the asthma attack, the alveolar gas is excessive, and the intrapulmonary pressure is significantly increased. The emphysema that has been complicated by chronic asthma can cause the pulmonary bullae to rupture, form a spontaneous pneumothorax, apply mechanical ventilation, airway and alveoli. The peak pressure is too high, it is also easy to cause alveolar rupture and form a barotrauma, causing pneumothorax and even with mediastinal emphysema.

5, respiratory failure

Severe asthma attacks, inadequate ventilation, infection, treatment and medication, pneumothorax, atelectasis and pulmonary edema are common causes of respiratory failure in asthma. In the event of respiratory failure, severe hypoxia, carbon dioxide retention and acidosis, Asthma treatment is more difficult, to eliminate and reduce the incentives, prevention occurs; after the occurrence of respiratory failure.

6, multiple organ dysfunction and multiple organ failure

Due to severe hypoxia, severe infection, acid-base imbalance, gastrointestinal bleeding and toxic side effects of drugs, severe asthma often complicated by multiple organ dysfunction or even functional failure, to prevent and correct the above incentives, and actively improve the function of various important organs.

7, long-term complications

(1) dysplasia and thoracic deformity, childhood asthma, often cause dysplasia and thoracic deformity, the factors are multi-faceted, such as nutritional deficiencies, hypoxemia, endocrine disorders, etc., have reported long-term systemic use of corticosteroids Children, 30% are stunted.

(2) Chronic obstructive pulmonary disease, pulmonary hypertension and chronic pulmonary heart disease are associated with long-term or repeated airway obstruction caused by asthma, infection, hypoxia, hypercapnia, acidosis and increased blood viscosity.

Asthma Symptoms Common Symptoms Bronchial secretions increase wheezing Both lungs are diffuse or scattered... Breathing difficulty wheezing cough with wheezing sputum tracheal obstruction chest tightness purpura

Typical bronchial asthma, there are aura symptoms such as sneezing, runny nose, cough, chest tightness, etc. before the attack, if not treated in time, asthma may occur due to aggravation of bronchial obstruction, severe cases may be forced to take a seat or sit in the breath, dry cough Or a large amount of white foam sputum, or even purpura, etc., but generally can be relieved by themselves or with self-administered or anti-asthmatic drugs. Some patients may relapse after a few hours of remission, and even lead to persistent asthma.

In addition, clinically there are atypical manifestations of asthma, such as cough variant asthma, patients with no obvious cause of cough for more than 2 months, night and early morning attacks, exercise, cold air and other induced aggravation, airway reactivity determination exists Highly reactive, antibiotics or antitussive, antispasmodic treatment is ineffective, effective with bronchial spasmolytic agents or corticosteroids, but other diseases that cause coughing need to be ruled out.

According to the presence or absence of allergens and age of onset, it is clinically divided into exogenous asthma and endogenous asthma. Exogenous asthma is often present in childhood, adolescents have a history of family allergies, and is a type I allergic reaction. Source asthma has many known allergens. In adults, there is no obvious seasonality, and there is little history of allergies, which may be caused by infection in the body.

Regardless of the type of asthma, mild symptoms can gradually resolve spontaneously, without any symptoms or abnormal signs during the remission period.

Asthma check

1, blood routine examination.

There may be an increase in eosinophils, such as concurrent infection, the total number of white blood cells may increase, and the proportion of classified neutrophils increases.

2, sputum check.

Such as combined respiratory bacterial infection, sputum smear, bacterial culture and drug sensitivity test to help pathogen diagnosis and guidance treatment.

3. Respiratory function check.

4, blood gas analysis.

5, chest X-ray examination.

6. Complement test of specific allergens.

7, skin sensitivity test.

Suspected allergens for skin scratches or intradermal tests during asthma remission, conditional inhalation challenge test, allergen diagnosis can be made, but it should be noted that highly sensitive patients may sometimes induce asthma and systemic reactions, and even allergies Shock, must be closely observed and deal with it in a timely manner.

Asthma diagnosis

diagnosis

First, the diagnostic criteria

1, repeated episodes of wheezing, difficulty breathing, chest tightness or cough, more related to contact with allergens, viral infections, exercise or certain irritants.

2, the two lungs can be heard and scattered or diffuse at the time of attack, with a wheezing sound mainly due to exhalation.

3. The above symptoms can be relieved by treatment or relieved by themselves.

4. Eliminate other diseases that can cause wheezing or difficulty breathing.

5. For those with atypical symptoms (such as no obvious wheezing or signs), at least one of the following tests should be positive:

(1) If the base FEV1 (or PEF) is <80% normal, FEV1 (or PEF) is increased by more than 15% after inhalation of the 2 agonist.

(2) PEF mutation rate (measured by expiratory peak flow meter, measured once in the morning and at night) 20%.

(3) The bronchial provocation test (or exercise challenge test) is positive.

Second, classification According to the history, symptoms, signs and laboratory findings, clinically divided asthma into two types of exogenous asthma and endogenous asthma.

Third, the severity of the disease is graded.

Asthma severity: Pre-treatment clinical manifestations: pulmonary function, treatment required to control symptoms, mild: intermittent episodes, 1 or 2 times per week. 80% of the predicted value of EFV1 (or PEF) requires only intermittent inhalation (or oral). 20 nights or less per night, PEF mutation rate 20% agonist or theophylline, asymptomatic between two episodes, EFV1 (or PEF) in the normal range after application of bronchodilator; moderate: weekly asthma attack >2 times, EFV1 (or PEF) is 60% to 80% of the predicted value, often need to use bronchodilator, monthly nighttime asthma attack>2 times, PEF mutation rate is between 20% and 30%, daily need Inhaled corticosteroids, inhaled 2 agonists in almost every episode, and EFV1 (or PEF) can be recovered after treatment. Severe: Frequent asthma, EFV1 (or PEF) < 60% of the estimated value, need to give daily bronchodilator, limited activity, PEF mutation rate > 30%, daily inhalation of large doses of corticosteroids.

Differential diagnosis

Bronchial asthma should be noted with asthmatic bronchitis, cardiogenic asthma caused by left heart failure, dyspnea due to airway obstruction caused by airway tumors, pulmonary eosinophilic infiltration and asthmatic differentiation caused by bronchiolitis in children .

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