Bronchial Asthma Prevention and Control Guidelines (2008) Bronchial Asthma Prevention and Control Guidelines (Definition, Diagnosis, Treatment and Management Plan of Bronchial Asthma) The Asthma Group of the Chinese Society of Respiratory Diseases Bronchial Asthma Prevention and Control Guidelines (asthma) is one of the common chronic respiratory diseases, and its prevalence has been increasing year by year in recent years worldwide. Many studies have shown that standardized diagnosis and treatment, especially long-term management, play an important role in improving the control of asthma and improving the quality of life of patients. This “guideline” is based on the “Bronchial Asthma Prevention and Control Guidelines” revised in 2003 in China, with reference to the 2006 edition of the Global Initiative for Asthma Prevention and Control (GINA), and revised with the results of evidence-based medical research at home and abroad in recent years, to provide a guiding document for the prevention and treatment of asthma in China. It provides a guiding document for the prevention and treatment of asthma in China. Zhou Haoquan, Department of Pediatrics, Anhui Provincial Hospital I. Definition Asthma is a chronic inflammatory disease of the airways involving a variety of cells, including inflammatory and structural cells of the airways (such as eosinophils, mast cells, T lymphocytes, neutrophils, smooth muscle cells, airway epithelial cells, etc.) and cellular elements. This chronic inflammation leads to airway hyperresponsiveness, usually with widespread and variable reversible airflow limitation, and causes recurrent episodes of wheezing, shortness of breath, chest tightness, or cough, which often flare up and worsen at night and/or early in the morning, with most patients relieving on their own or with treatment. The risk factors for the development of asthma include both host factors (genetic factors) and environmental factors. Diagnosis (a) Diagnostic criteria Recurrent episodes of wheezing, shortness of breath, chest tightness or cough are mostly associated with exposure to allergens, cold air, physical and chemical stimuli, as well as viral upper respiratory tract infections and exercise. During the attacks, a scattered or diffuse, expiratory phase dominated croup with prolonged expiratory phase can be heard in both lungs. These signs and symptoms may resolve with treatment or may resolve on their own. In addition to wheezing, shortness of breath, chest tightness and cough caused by other diseases. Those with atypical clinical manifestations (e.g., no obvious wheezing or signs) should have at least 1 of the following positive tests: (1) positive bronchial excitation test or exercise excitation test; (2) positive bronchial diastolic test with ≥12% increase in FEV1 and absolute FEV1 increase ≥200 ml; (3) intra-day (or 2-week) variability of peak expiratory flow (PEF) ≥20 %. Those who meet 1 to 4 or 4 or 5 can be diagnosed as asthma. (B) Staging According to clinical manifestations asthma can be divided into acute exacerbation, chronic persistent and clinical remission. The chronic persistent phase refers to the symptoms (wheezing, shortness of breath, chest tightness, cough, etc.) occurring at different frequencies and/or to different degrees every week; the clinical remission phase refers to the disappearance of symptoms and signs with or without treatment, and the return of lung function to the level before the acute exacerbation, which is maintained for more than 3 months. (iii) Grading of grading severity of disease: mainly used to judge the severity before treatment or at the time of initial treatment, and has its application value more in clinical research. See Table 1. grading of control level: see Table 2. this grading method is more easily grasped by clinicians and helps to guide clinical treatment to achieve better asthma control. Grading of acute asthma attack: An acute asthma attack is the sudden onset of wheezing, shortness of breath, cough and chest tightness, or a sharp aggravation of existing symptoms, often with dyspnea, characterized by reduced expiratory flow, and often triggered by exposure to allergens, irritants or respiratory infections. The degree of severity varies, and the exacerbation can occur within hours or days, or occasionally within minutes, so the condition should be properly evaluated in order to provide timely and effective emergency treatment. The grading of the severity of an acute asthma attack is shown in Table 3. Note: As long as certain indicators of a certain severity level are met, but not all indicators need to be met, an acute attack of that level can be indicated. (iv) Related diagnostic tests Pulmonary function measurement helps to confirm the diagnosis of asthma and is one of the important bases for assessing the degree of asthma control. In patients with asthma symptoms but normal lung function, measurement of airway responsiveness and PEF intra-day variability can help to confirm the diagnosis of asthma. Eosinophil or neutrophil counts in sputum can assess airway inflammation associated with asthma. Exhaled breath components such as NO partial pressure (FeNO) can also be used as a noninvasive marker of airway inflammation in the setting of asthma. Sputum eosinophil and FeNo tests are useful in selecting the optimal asthma treatment regimen. Allergen skin test or serum specific IgE assay can be used to confirm the allergic status of asthma patients to help understand the risk factors that contribute to the development and exacerbation of individual asthma, and also to help determine the specific immunotherapy regimen. Commonly used drugs for asthma can be divided into controlling drugs and relieving drugs. (1) Control medications: These are medications that require long-term daily use. These drugs are mainly used to maintain clinical control of asthma through anti-inflammatory effects, including inhaled glucocorticoids (hormones), systemic hormones, leukotriene modulators, long-acting β2-agonists (LABA, which must be used in combination with inhaled hormones), extended-release theophylline, sodium cromoglycate, anti-IgE antibodies and other drugs that help to reduce the dose of systemic hormones, etc.; (2) relief drugs: they are used on an as-needed basis. drugs. These drugs relieve asthma symptoms by rapidly relieving bronchospasm, and include fast-acting inhaled β2-agonists, systemic hormones, inhaled anticholinergics, short-acting theophylline and short-acting oral β2-agonists. (i) Hormones Hormones are the most effective drugs for controlling airway inflammation. The routes of administration include inhalation, oral and intravenous application. Inhalation is the preferred route. Inhalation administration: Inhalation hormone has strong local anti-inflammatory effect; through the inhalation process, the drug acts directly on the respiratory tract and requires a smaller dose. Most of the drugs entering the bloodstream through the gastrointestinal and respiratory tracts are inactivated by the liver, and therefore systemic adverse effects are less frequent. The results of the study prove that inhaled hormones can effectively reduce asthma symptoms, improve quality of life, improve lung function, reduce airway hyperresponsiveness, control airway inflammation, reduce the frequency and severity of asthma attacks, and reduce the morbidity and mortality rate. When different inhalation devices are used, they may produce different therapeutic effects. Most adults with asthma have good control of their asthma with small doses of inhaled hormones. Excessive increases in inhaled hormone doses have less benefit and more adverse effects on asthma control. Because smoking can reduce the effectiveness of hormones, patients who smoke must quit smoking and be given higher doses of inhaled hormones. There is a very clear relationship between the dose of inhaled hormone and the prevention of severe acute asthma attacks, so high doses of inhaled hormone over a long period of time are beneficial in patients with severe asthma. Local adverse effects of inhaled hormones in the oropharynx include hoarseness, pharyngeal discomfort, and Candida infection. The above-mentioned adverse effects can be reduced by rinsing the oropharynx with water promptly after inhalation, choosing dry powder inhalers or adding a nebulizer. The magnitude of systemic adverse reactions to inhaled hormones is related to the drug dose, bioavailability of the drug, absorption in the intestinal tract, hepatic first-pass metabolism rate and half-life of systemically absorbed drugs. Among the marketed inhaled hormones, fluticasone propionate and budesonide have fewer systemic adverse reactions. There is evidence that adult asthmatics who inhale low to moderate doses of hormones daily do not experience significant systemic adverse effects. Possible systemic adverse effects following long-term high doses of inhaled hormones include skin petechiae, suppression of adrenal function, and decreased bone mineral density. There has been research evidence that inhaled hormones may be associated with the development of cataracts and glaucoma, but there is no evidence from prospective studies of a clear association with the development of posterior subcapsular cataracts. There is no evidence that inhaled hormones can increase the incidence of pulmonary infections (including tuberculosis), so patients with asthma with active tuberculosis can be given inhaled hormone therapy in conjunction with anti-tuberculosis treatment. (1) Aerosol: There are four types of ICS commonly used in clinical practice (see Table 4). (2) Dry powder inhalers: including beclomethasone dipropionate discs, budesonide duplex, fluticasone propionate discs, etc. Generally speaking, the use of dry powder inhalation device is more convenient than ordinary quantitative aerosol, and the amount of drugs inhaled into the lower respiratory tract is higher. (3) Solution: Budesonide solution is nebulized and inhaled by a jet device powered by compressed air, which does not require high inspiratory cooperation from patients and has a faster onset of action, and is suitable for the treatment of acute asthma attacks. It is the drug of choice for long-term treatment of asthma. The internationally recommended daily dose of ICS is shown in Table 4, and the dose of ICS required for asthma patients in China is smaller than the recommended dose in Table 4. Oral administration: For patients with moderate asthma exacerbations, chronic persistent asthma where inhalation of high-dose inhaled hormone combination therapy is ineffective and as sequential therapy after intravenous application of hormone therapy. Hormones with a short half-life (e.g., prednisone, prednisolone, or methylprednisolone) are generally used. For hormone-dependent asthma, daily or alternate morning dosing can be used to reduce the suppressive effect of exogenous hormones on the hypothalamic-pituitary-adrenal axis. Long-term oral hormone administration can cause osteoporosis, hypertension, diabetes mellitus, hypothalamic-pituitary-adrenal axis suppression, obesity, cataracts, glaucoma, skin thinning leading to skin tags and ecchymosis, and muscle weakness. Systemic hormone therapy for asthma with tuberculosis, parasitic infections, osteoporosis, glaucoma, diabetes, severe depression or peptic ulcer should be administered with caution and closely followed. Patients with asthma on long-term or even short-term systemic hormone therapy can be infected with the deadly herpes virus and it is necessary to avoid exposure to the herpes virus in these patients. Although systemic hormones are not a frequently used method of relieving asthma symptoms, they are needed for severe acute asthma because they can prevent worsening of asthma, reduce the chance of emergency room visits or hospitalization for asthma, prevent early relapses, and reduce morbidity and mortality. Recommended dose: Prednisolone 30-50 mg/d for 5-10 d. Specific use depends on the severity of the disease, and discontinuation or dose reduction may be considered when symptoms have resolved or their lung function has reached a personal best. Dexamethasone is not recommended for long-term use due to its high pituitary-adrenal suppressive effect. Intravenous administration: In severe acute asthma attacks, hydrocortisone succinate (400-1,000 mg/d) or methylprednisolone (80-160 mg/d) should be given intravenously in a timely manner. For those without hormone dependence, the drug can be stopped within a short period of time (3-5 d); for those with hormone dependence, the duration of administration should be prolonged, and after controlling asthma symptoms, the drug should be given orally, and the amount of hormone should be gradually reduced. (B) β2-receptor agonists can relieve asthma symptoms through the action of β2-receptors on the surface of airway smooth muscle and mast cells, which can relax airway smooth muscle, reduce the release of mast cell and basophil degranulation and mediators, reduce the permeability of microvessels and increase the oscillation of airway epithelial cilia. There are many such drugs, which can be divided into short-acting (action maintained for 4-6 h) and long-acting (maintained for 12 h) β2-agonists. The latter can be divided into two types of fast-acting (onset of action in minutes) and slow-acting (onset of action in 30 min), see Table 5. Short-acting β2-agonists (SABA): commonly used drugs such as salbutamol and terbutalin. Inhalation administration: Short-acting β2-agonists available for inhalation include aerosols, dry powders and solutions. These drugs have a strong effect of relaxing airway smooth muscle, usually within a few minutes, the effect can be maintained for several hours, is the first choice of drugs to relieve mild to moderate acute asthma symptoms, can also be used for exercise asthma. If the effect is not satisfactory after 1 h, consult a doctor or go to the emergency room. These drugs should be used intermittently as needed and should not be used for a long period of time or in excessive amounts, as they may cause skeletal muscle tremor, hypokalemia, cardiac rhythm disorders and other adverse effects. Pressure-type quantitative hand-controlled aerosol (pMDI) and dry powder inhalation device inhalation short-acting β2-agonist is not suitable for severe asthma attacks; its solution (such as salbutamol, terbutaline, fenoterol and its compound) by nebulizer pump inhalation is suitable for mild to severe asthma attacks. Oral administration: such as salbutamol, terbutaline, and procarterol tablets, usually take effect 15-30 min after taking the drug, and the effect is maintained for 4-6 h. For example, salbutamol 2-4 mg, terbutaline 1.25-2.5 mg, 3 times a day; procarterol 25-50 μg, 2 times a day. Although the use of more convenient, but palpitations, skeletal muscle tremor and other adverse reactions than the inhalation administration is obvious. The duration of the asthma-suppressing effect of the extended-release and controlled-release formulations can be maintained for 8-12 h. The effect of bambuterol, the precursor of terbutaline, can be maintained for 24 h, which can reduce the number of doses and is suitable for the prevention and treatment of nocturnal asthma patients. Long-term, single application of β2-agonists can cause downward regulation of cell membrane β2-receptors, manifesting as clinical drug resistance, and should be avoided. Injection administration: Although the effect of asthma is more rapid, but because of the high incidence of systemic adverse reactions, it is less used in China. Patch administration: transdermal absorption dosage form. Existing products are tulobuterol, divided into 0.5 mg, 1 mg, 2 mg 3 kinds of doses. Because the crystalline storage system is used to control the release of the drug, the drug is absorbed through the skin, so it can reduce systemic adverse reactions, only need to be applied once a day, the effect can be maintained for 24 h. Effective for the prevention of morning descent, the use of simple methods. The LABA: This kind of β2-agonist has a long side chain in the molecular structure, and the effect of diastolic bronchial smooth muscle can be maintained for more than 12 hours. At present, there are two types of inhaled LABA in clinical use in China. Salmeterol: It is administered by aerosol or disc device, and it takes effect 30 min after administration, and the effect of asthma can be maintained for more than 12 hours. The recommended dose is 50 μg, twice daily by inhalation. Formoterol: It is administered by inhalation device, with an onset of action 3-5 min after administration, and the asthmatic effect is maintained for more than 8-12 hours. The effect of asthma has a certain dose-dependence, the recommended dose is 4.5-9μg, 2 inhalations per day. Inhalation of LABA is suitable for the prevention and treatment of asthma (especially nocturnal asthma and exercise-induced asthma). Formoterol can be used on an as-needed basis for the treatment of acute asthma attacks because of its rapid onset of action. In recent years, the combination of inhaled hormones and LABA has been recommended for the treatment of asthma. They have synergistic anti-inflammatory and antiasthmatic effects and can achieve efficacy equivalent to (or better than) that achieved with doubled doses of inhaled hormone, and can increase patient compliance and reduce adverse effects associated with higher doses of inhaled hormone. Long-term use of LABA alone is not recommended and should be used in combination with inhaled hormones under medical supervision. (iii) Leukotriene modulators include cysteinyl leukotriene receptor antagonists and 5-lipoxygenase inhibitors. Apart from inhaled hormones, they are the only long-acting control agents that can be applied alone, and can be used as alternative treatment drugs for mild asthma and combined treatment drugs for moderate to severe asthma. Currently, cysteinyl leukotriene receptor antagonists are mainly used in China to inhibit the wheezing and inflammatory effects of cysteinyl leukotrienes released from mast cells and eosinophils by antagonizing leukotriene receptors on the surface of airway smooth muscle and other cells, producing mild bronchodilation and reducing allergens, exercise and sulfur dioxide (SO2)-induced bronchospasm, as well as having a certain degree of anti-inflammatory effect. It also has a degree of anti-inflammatory effect. This product can reduce asthma symptoms, improve lung function and reduce the deterioration of asthma. However, it is not as effective as inhaled hormones and cannot replace them. As one of the drugs in combination therapy, it can reduce the daily dose of inhaled hormone in patients with moderate to severe asthma and improve the clinical efficacy of inhaled hormone therapy, but the efficacy of combining this product with inhaled hormone is slightly worse than that of combining inhaled LABA with inhaled hormone. However, this product is convenient to take. It is especially suitable for the treatment of patients with aspirin asthma, exercising asthma and asthma with allergic rhinitis. This product is relatively safe to use. Although Churg-Strauss syndrome has been reported in patients treated with these drugs, the causal relationship with leukotriene modulators has not been established and may be related to a reduction in the dose of systemic hormones. 5-Lipoxygenase inhibitor zileuton may cause liver damage, and liver function should be monitored. It is usually administered orally. The leukotriene receptor antagonist zallust 20 mg twice daily, montelukast 10 mg once daily, and isatinost 10 mg twice daily. (D) theophylline has the effect of diastolic bronchial smooth muscle, and has cardiac, diuretic, coronary artery dilation, respiratory center and respiratory muscle excitation and other effects. Some research data show that low concentration of theophylline has anti-inflammatory and immunomodulatory effects. As a symptom reliever, although theophylline is still used intravenously in the treatment of severe asthma in clinical practice, short-acting theophylline for asthma exacerbation or worsening is controversial because it has no advantage in diastaging the bronchi, compared with rapid beta2-agonists used in adequate doses, but it may improve respiratory drive. Short-acting theophylline is not recommended for patients already on long-term extended-release theophylline, except when that patient has a low serum theophylline concentration or when serum theophylline concentration monitoring is available. Oral administration: Includes aminophylline and controlled (extended) release theophylline. For mild to moderate asthma attacks and maintenance therapy. The general dose is 6-10 mg/kg/day, and the oral controlled (extended) release theophylline has a stable blood concentration around the clock and can maintain the asthma control effect for 12-24 h. It is especially suitable for the control of asthma symptoms at night. The combination of theophylline, hormone and anticholinergic drugs has synergistic effect. However, when combined with β2-agonists, it may cause increased heart rate and arrhythmia, so it should be used with caution and the dose should be reduced. Intravenous administration: Aminophylline should be added to glucose solution and injected slowly intravenously (the injection rate should not exceed 0.25 mg kg-1 min-1) or intravenously by drip, for patients with acute asthma attacks who have not used theophylline drugs in the last 24 hours. Because of the narrow “therapeutic window” of theophylline and the large individual differences in theophylline metabolism, it can cause cardiac arrhythmia, blood pressure drop, and even death. The concentration and titration rate should be adjusted in time. The effective and safe blood concentration of theophylline should be in the range of 6-15 mg/L. There are many factors affecting theophylline metabolism, such as febrile diseases, pregnancy, anti-tuberculosis treatment can reduce the blood concentration of theophylline; while liver disorders, congestive heart failure and the combination of metformin or quinolones, macrolides and other drugs can affect the metabolism of theophylline and slow down its excretion, increasing the toxic effects of theophylline, which should attract the attention of clinicians and adjust the dose as appropriate. The effect of doxorubicin is the same as aminophylline, but the adverse effects are lighter. The effect of dihydroxypropyl theophylline is weaker, and less adverse reactions. (v) Anticholinergic drugs, such as ipratropium bromide, oxytropium bromide and tiotropium bromide, can block the postganglionic vagal efferent branch, which can relax the bronchi by decreasing the vagal tone. Its bronchodilator effect is weaker than that of β2-agonists, and the onset of action is slower, but long-term application is less likely to produce drug resistance, and its efficacy in the elderly is no less than that of the young. The product is available in aerosol and nebulized solution forms. The common dose of ipratropium bromide aerosol by pMDI inhalation is 20-40μg, 3-4 times a day; the common dose of ipratropium bromide solution by nebulizer pump inhalation is 50-125μg, 3-4 times a day. It is a new long-acting anticholinergic drug with selective inhibitory effect on M1 and M3 receptors, and only needs to be administered by inhalation once a day. It has a synergistic and complementary effect with β2-agonists in combination. It is suitable for elderly asthmatic patients with a history of smoking, but should be used with caution in women in early pregnancy and in patients with glaucoma or prostatic hypertrophy. Although ipratropium bromide has been used in some patients with asthma due to intolerance of beta2-agonists, there is no evidence to date that it has a significant effect on the long-term management of asthma. (vi) Anti-IgE therapy Anti-IgE monoclonal antibody (omalizumab) can be used in asthma patients with increased serum IgE levels. Currently it is mainly used in patients with severe asthma whose symptoms are not controlled after combined treatment with inhaled glucocorticoids and LABA. No significant adverse effects of anti-IgE therapy have been found in treatment studies of asthma patients aged 11 to 50 years, but because the clinical use of this drug is still short, its long-term efficacy and safety need further observation. The high price also limits its clinical application. (vii) Allergen-specific immunotherapy can reduce asthma symptoms and airway hyperresponsiveness through subcutaneous administration of common inhaled allergen extracts (e.g. dust mite, cat hair, ragweed, etc.), which is suitable for asthma patients with clear allergens but difficult to avoid. Its long-term efficacy and safety are yet to be further studied and evaluated. The standardization of allergen preparation also needs to be enhanced. The application of this therapy in asthma patients should be strictly under the guidance of a physician. Sublingual administration of allergen immunotherapy has been tried, and SIT should be considered in cases where strict environmental isolation and pharmacological interventions (including inhaled hormones) are not effective. There are no studies comparing the difference in efficacy between it and pharmacological interventions. There is no evidence to support the value of immunotherapy with compound allergens. (viii) Other drugs for asthma. Antihistamines: Oral second-generation antihistamines (H1 receptor antagonists) such as ketotifen, loratadine, astemizole, azelastine, terfenadine, etc. have anti-allergic effects, but their role in asthma treatment is weak. They can be used in the treatment of asthma patients with allergic rhinitis. The main adverse effect of these drugs is drowsiness. Astemizole and terfenadine can cause serious cardiovascular adverse reactions and should be used with caution. The Other oral anti-allergic drugs such as tranilast and repirinast can be used in the treatment of mild to moderate asthma. Its main adverse effect is drowsiness. The Drugs that may reduce the dose of oral glucocorticoid hormone: including oral immunomodulators (methotrexate, cyclosporine, gold preparations, etc.), certain macrolide antibiotics and intravenous application of immunoglobulin. Their efficacy is yet to be further studied. The Chinese herbal medicine: the use of evidence-based treatment can help the treatment of asthma in chronic remission. It is necessary to carry out a multicenter randomized double-blind clinical study on Chinese medicines or formulas with more definite clinical efficacy. Asthma is a chronic disease that has a significant impact on patients, their families and society. Airway inflammation is a common feature of almost all types of asthma and underlies the clinical symptoms and airway hyperresponsiveness. Airway inflammation is present in all periods of asthma. Although there is no cure for asthma, standardized treatment focused on suppressing inflammation can control the clinical symptoms of asthma. An international study has shown asthma control rates approaching 80% with fixed-dose escalation and maintenance treatment with fluticasone/salmeterol. Although the cost of controlling asthma may seem high from the patient’s and society’s point of view, the cost of incorrectly treating asthma can be even higher. (i) Determination of long-term treatment regimen Asthma treatment should be based on the severity of the patient’s condition and the appropriate treatment regimen should be selected according to his or her level of control category. The choice of asthma medication should take into account both the efficacy of the medication and its safety, as well as the actual situation of the patient, such as economic income and local medical resources. An asthma control plan should be developed for each initial patient, with regular follow-up and monitoring to improve patient compliance and timely revision of the treatment plan according to changes in the patient’s condition. Long-term treatment regimens for asthma patients are divided into 5 levels, as shown in Table 6. Level 2 treatment regimens can be selected for patients with primary asthma who have not been previously treated in a standardized manner, and patients with asthma who have significant symptoms should be directly selected for level 3 treatment regimens. Different asthma control medications are available in the treatment regimens from level 2 to level 5. And in each level, relief medications should be used as needed to provide rapid relief of asthma symptoms. When combined therapy with a single inhalation device containing formoterol and budesonide is used, it can be applied as a control and relief medication. If asthma control is not achieved with this tiered regimen, the regimen should be escalated until asthma control is achieved. When asthma is controlled and maintained for at least 3 months, the regimen may be considered for downgrading. Suggested reduction regimen: (1) reduce inhaled hormone dose by 50% for patients on moderate to high dose inhaled hormone alone; (2) switch to once daily dosing for patients on low dose hormone alone; 3. reduce inhaled hormone dose by approximately 50% for patients on combination inhaled hormone and LABA and still continue with combination LABA therapy. When a low dose of combination therapy is reached, there is an option to change to a once daily combination or to discontinue the LABA and treat with inhaled hormone alone. If the patient achieves asthma control with the lowest dose of control medication for 1 year and no more asthma symptoms occur, discontinuation of medication may be considered. The above dose reduction regimen is subject to further validation. Usually, patients return 2 to 4 weeks after the initial diagnosis and are followed up every 1 to 3 months thereafter. Asthma attacks should be seen promptly when they occur, and return visits should be made within 2 weeks to 1 month after the asthma attack. For asthma patients in poor areas or low economic income in China, depending on the severity of their disease, the recommended medications for long-term asthma control are: (1) inhaled low-dose hormones; (2) oral extended-release theophylline; (3) inhaled hormones combined with oral extended-release theophylline; and (4) oral hormones and extended-release theophylline. The efficacy and safety of these treatment options need further clinical studies, especially to monitor the possible systemic adverse effects caused by long-term oral hormone administration. (B) Treatment of acute asthma attacks depends on the severity of the attack and the response to treatment. The aim of treatment is to relieve symptoms, airflow limitation and hypoxemia as soon as possible, and also to develop a long-term treatment plan to prevent further acute attacks. Patients with high risk factors for asthma-related mortality need to be given high priority and these patients should be seen at the earliest possible time by a health care provider. Patients at high risk include: (1) a history of near-fatal asthma with tracheal intubation and mechanical ventilation; (2) hospitalization or emergency room visits for asthma in the past 1 year; (3) current or recently discontinued oral hormone use; (4) not currently using inhaled hormones; (5) over-reliance on rapid-acting β2-agonists, especially if using more than 1 salbutamol (or equivalent) per month patients; (6) psychological disorders or psychosocial problems, including sedation use; (6) history of noncompliance with asthma treatment plans. Mild and some moderate acute exacerbations can be treated in the home or in the community. Treatment at home or in the community consists primarily of repeated inhalation of a rapid-acting β2-agonist, with two to four sprays inhaled every 20 min during the first hour. Subsequently, depending on the response to treatment, mild acute attacks can be adjusted to 2-4 sprays every 3-4 h, and moderate acute attacks to 6-10 sprays every 1 to 2 h. If the response to inhaled β2-agonists is good (significant relief of dyspnea, PEF >80% of expected value or personal best, and efficacy maintained for 3 to 4 h), no other medication is usually required. If the response to therapy is incomplete, especially in acute attacks occurring on the basis of controlled therapy, oral hormones (prednisolone 0.5-1 mg/kg or equivalent doses of other hormones) should be administered as early as possible, and hospital visits should be made if necessary. Some moderate and all severe acute attacks should be treated in the emergency room or hospital. In addition to oxygen therapy, a rapid-acting β2-agonist should be repeated, either administered through a pressure-dosing aerosol reservoir or through a jet nebulization device. Continuous nebulized dosing is recommended for initial treatment, followed by intermittent dosing as needed (1 dose every 4 h). There is no evidence to support the routine intravenous use of β2 agonists. Better bronchodilatory effects are achieved with the combination of β2-agonists and anticholinergic agents (e.g. ipratropium bromide). The bronchodilatory effect of theophylline is weaker than that of SABA and should be used with caution due to greater adverse effects. Theophylline blood levels should be monitored as much as possible in patients taking theophylline extended-release preparations intravenously. Systemic hormones should be used as early as possible in acute attacks of moderate to severe asthma, especially in patients with incomplete response to initial treatment with rapid-acting β2-agonists or whose efficacy cannot be maintained, and in patients who still have acute attacks on the basis of oral hormones. Oral hormones are comparable in efficacy to intravenous administration and have fewer side effects. Recommended Use: Prednisolone 30 to 50 mg or equivalent other hormone given as a single daily dose. In severe acute attacks or when oral hormones are not tolerated, intravenous injections or drips, such as methylprednisolone 80-160 mg or hydrocortisone 400-1000 mg in divided doses, may be used. Dexamethasone is generally not recommended because of its long half-life and strong suppressive effect on adrenocortical function. Sequential therapy with intravenous and oral administration has the potential to reduce hormone dosage and adverse effects, such as 2-3 d of intravenous hormones followed by 3-5 d of oral hormones. magnesium preparations are not recommended for routine use in severe acute exacerbations (FEV1 25%-30%) or in those who do not respond well to initial therapy. The process of in-hospital treatment of acute asthma attacks is shown in Figure 1. Severe and critical acute asthma attacks without improvement of clinical symptoms and pulmonary function or even continued deterioration after the above-mentioned pharmacological treatment should be promptly treated with mechanical ventilation, the indications of which include: altered consciousness, respiratory muscle fatigue, PaCO2 ≥ 45 mm Hg (1 mm Hg = 0.133 kPa), etc. Non-invasive mechanical ventilation via nasal (face) mask can be used first, and if there is no effect, early mechanical ventilation by tracheal intubation can be performed. Mechanical ventilation for acute asthma attacks requires high inspiratory pressure and can be treated with appropriate levels of positive end-expiratory pressure (PEEP). If excessive peak and plateau airway pressures are required to maintain normal ventilation volume, a permissive hypercapnic ventilation strategy may be tried to reduce ventilator-associated lung injury. Those with significant symptomatic improvement on initial therapy and PEF or FEV1 % of predicted return to or above 60% of personal best may return home for continued treatment, those with PEF or FEV1 of 40% to 60% should return to home or community under supervision for continued treatment, and those with pre-treatment PEF or FEV1