Bronchial asthma is a chronic inflammatory disease of the airways involving a variety of cells and cellular components. This chronic inflammation is associated with airway hyperresponsiveness and usually presents with widespread and variable reversible airflow limitation, resulting in recurrent episodes of wheezing, shortness of breath, chest tightness and/or coughing, mostly at night and/or early in the morning, and intensifying, with most patients relieving themselves or with treatment. 1.Genetic factors Asthma is related to polygenic inheritance. The prevalence of asthma in relatives is higher than that in the group, and the closer the relatives are, the higher the prevalence; the more severe the patient’s disease is, the higher the prevalence in his relatives. 2. Allergens (1) Indoor and outdoor allergens Dust mites are the most common and harmful indoor allergens, and are an important cause of asthma worldwide. Fungi are also present in indoor air, especially in dark, humid and poorly ventilated areas. Common outdoor allergens: Pollen and grass pollen are the most common outdoor allergens that cause asthma attacks. (2) Occupational allergens Common allergens include grain flour, flour, wood, feed, tea, coffee beans, silkworm, pigeons, mushrooms, antibiotics (penicillin, cephalosporin), rosin, reactive dyes, persulfates, ethylenediamine, etc. (3) Drugs and food additives Aspirin, Prenalol and some non-corticosteroid anti-inflammatory drugs are the main allergens of drug-induced asthma. 3.Promotional factors Common air pollution, smoking, respiratory virus infection, pregnancy and strenuous exercise, climate change; a variety of non-specific stimuli such as: inhalation of cold air, distilled water droplets, etc. can trigger asthma attacks. In addition, asthma can be triggered by psychological factors. Clinical manifestations Episodes of expiratory dyspnea with croup or episodes of cough and chest tightness. In severe cases, the patient is forced to sit or breathe in a sedentary position, coughing dryly or coughing up large amounts of white foamy sputum, or even cyanosis, etc. Sometimes coughing may be the only symptom (cough variant asthma). In some adolescent patients, chest tightness, cough and dyspnea during exercise are the only clinical manifestations (exercise asthma). Asthma symptoms may come on within minutes and resolve over hours to days with bronchodilators or on their own. Some patients may have a relapse after a few hours of remission. Nocturnal and early morning attacks and exacerbations are often a feature of asthma. Examination 1. Physical examination The chest is hyperinflated during an attack, the thorax is inflated, percussion is hyperclear, and most have extensive expiratory-phase predominant croup with prolonged expiration. Severe asthma attacks often have signs such as labored breathing, profuse sweating, cyanosis, paradoxical chest and abdominal movements, increased heart rate, and odd pulse. In remission, there may be no abnormal signs. 2. Laboratory and other tests (1) Routine blood tests Some patients may have increased eosinophils during the attack, but most of them are not obvious, and there may be increased white blood cell count and increased proportion of classified neutrophils if the infection is complicated. (2) Sputum examination smear More eosinophils can be seen. If combined with respiratory bacterial infection, sputum smear Gram stain, cell culture and drug sensitivity test can help to diagnose the pathogenic bacteria and guide the treatment. (3) Pulmonary function test Most of the pulmonary ventilation function is in normal range during the remission period. During asthma exacerbation, due to restricted expiratory flow rate, it is manifested by reduced first second forceful expiratory volume (FEV1), one second rate (FEV1/FVC%), maximum mid-expiratory flow rate (MMER), maximum expiratory flow rate at 50% and 75% of exhaled lung volume (MEF50% and MEF75%), and peak expiratory flow rate (PEFR). There may be a decrease in exertional lung volume, an increase in residual air volume, an increase in functional residual air volume and total lung volume, and an increase in residual air as a percentage of total lung volume. It may gradually recover after treatment. (4) Blood gas analysis In severe asthma attacks, there may be hypoxia, PaO2 and SaO2 decrease, and PaCO2 may fall and pH rise due to hyperventilation, showing respiratory alkalosis. If severe asthma, the condition further develops, airway obstruction is serious, there may be hypoxia and CO2 retention, PaCO2 rises, and manifest respiratory acidosis. If hypoxia is obvious, metabolic acidosis may be combined. (5) Chest X-ray examination In the early stage of asthma attack, increased translucency and hyperinflation of both lungs can be seen; in the remission period, there are mostly no obvious abnormalities. If there is concurrent respiratory tract infection, increased lung texture and inflammatory infiltrative shadows are seen. The presence of complications such as pulmonary atelectasis, pneumothorax or mediastinal emphysema should also be noted. (6) Detection of specific allergens Most patients with asthma have allergies and are sensitive to numerous allergens and irritants. Measurement of allergenic indicators combined with medical history can help in the etiologic diagnosis of the patient and in the removal of exposure to allergenic factors. However, allergic reactions should be prevented. Diagnosis The clinical diagnosis can be made in patients with typical symptoms and signs, except wheezing, shortness of breath, chest tightness and cough caused by other diseases; in atypical cases, a bronchodilator or excitation test should be performed, and a positive one can confirm the diagnosis. Differential diagnosis 1, wheezing-like dyspnea caused by left heart failure Most often seen in the elderly. The causes are: hypertension, coronary arteriosclerosis, mitral stenosis or chronic nephritis, etc. Episodes are more common with nighttime paroxysms. The symptoms are chest tightness, shortness of breath and difficulty, cough and croup, cyanosis, gray face, cold sweat, nervousness and fear in severe cases, similar to acute asthma attacks. In addition to croup, patients often have a large amount of thin watery or foamy sputum or possibly pink foamy sputum, and have a typical pulmonary base of a wet stall brain mirage. There are signs of pulmonary edema in the lungs and vascular shadowing is blurred. Due to pulmonary edema, the lobe septum becomes broad and the lobe septal line may move down to the basal lobe, which is helpful for differentiation. 2, chronic obstructive pulmonary disease Most commonly seen in middle-aged and elderly people with a history of chronic cough, wheezing perennially, with exacerbation periods. Asthmatic eosinophilic pneumonia, tropical pulmonary eosinophilia and pulmonary necrotizing vasculitis can be included in this group of diseases, they may have asthmatic symptoms, especially asthmatic eosinophilic pneumonia is particularly obvious. The disease is seen at any age and is mostly associated with bacterial infections of the lower respiratory tract. Patients are allergic to Aspergillus, hence the name allergic bronchopulmonary aspergillosis. Patients often have fever, and chest X-rays reveal multiple, intermittent, faint patchy infiltrative shadows that may disappear on their own or recur repeatedly. Lung tissue biopsy helps to identify. 4.Tracheal and main bronchial lung cancer Due to the compression or invasion of trachea or main bronchus by cancer, the lumen of upper airway is narrowed or incompletely obstructed, and coughing or wheezing, even with croup, occurs. However, patients usually have no history of asthma attack, sputum may be bloody, wheezing symptoms are mostly inspiratory dyspnea, or croup is limited, and treatment with wheezing drugs is ineffective. As long as the disease is considered, further chest X-ray, CT, sputum cytology and fiberoptic bronchoscopy will not be difficult to identify. Treatment There is no special treatment yet, but adherence to long-term standardized treatment can result in good control of asthma symptoms and reduce recurrence or even no more attacks. 1.Treatment goals (1) complete control of symptoms; (2) prevention of disease attacks or exacerbation; (3) lung function close to the individual best value; (4) normal mobility; (5) improve self-awareness and ability to deal with acute exacerbations, reduce the chance of emergency or hospitalization; (6) avoid adverse drug reactions; (7) prevent irreversible airway obstruction; (8) prevent death caused by asthma. (2) Basic clinical strategies for asthma prevention and treatment (1) Long-term anti-inflammatory therapy is the basic treatment, and inhaled hormones are preferred. (2) The drug of choice for emergency symptom relief is inhaled beta2 agonist. (3) If the condition is not satisfactorily controlled after regular inhaled hormone, it is appropriate to add inhaled long-acting β2 agonist, or slow-release theophylline, or leukotriene modulator (combined medication); it is also considered to increase the amount of inhaled hormone. (4) In patients with severe asthma, if they still have recurrent attacks for a long time after the above treatment, intensive treatment can be considered. In other words, the patient should be treated according to the treatment of severe asthma attack (high-dose hormone and other treatment), and the hormone dosage should be gradually reduced 2 to 4 days after the symptoms are completely controlled, the lung function is back to the optimal level and the fluctuation rate of PEF is normal. Some patients have ideal disease control after intensive treatment phase. 3.Therapeutic measures of comprehensive treatment (1)Eliminate the cause and precipitating cause. (2) Prevention and control of coexisting diseases, such as: allergic rhinitis, reflux esophagitis, etc. (3) Immunomodulatory therapy. (4) Frequent checking of the correct use of inhaled medication and compliance with medical advice. Education and management of asthma Education and management of asthma patients is an important measure to improve the efficacy, reduce recurrence and improve the quality of life of patients. Doctors should formulate a prevention and treatment plan for each initial asthma patient so that patients understand or master the following: 1. believe that through long-term, appropriate and adequate treatment, asthma attacks can be completely and effectively controlled; 2. understand the triggering factors of asthma, and combine each individual’s specific situation to Learn to monitor and evaluate changes at home, with emphasis on the use of peak flow rate meters, and to keep an asthma diary if possible; 6. 7.Know the role, correct dosage, usage and adverse effects of commonly used asthma medications; 8.Master the correct usage of different inhalation devices; 9.Know when to go to the hospital for medical treatment.