Bronchial asthma is a common clinical disease, and its common complications mainly include lower respiratory tract and lung infections, imbalance of water, electrolyte and acid-base balance, respiratory failure, pneumothorax and mediastinal emphysema, mucus plug formation and pulmonary atelectasis, and cardiac arrhythmias. Once complications occur in the course of treatment, they affect the efficacy and prognosis of asthma, so they should be taken seriously. 1. Lower respiratory tract and lung infections According to statistics, about half of the asthma patients are induced by viral infections in the upper respiratory tract, which are easily followed by lower respiratory tract and lung infections due to the disturbance of the immune function of the respiratory tract. Therefore, during the remission period, patients with asthma should improve their immune function, keep the airway clear, remove airway secretions, keep the room clean, and prevent colds to reduce the chance of infection; once there is an aura of infection, antibiotic treatment should be applied empirically as early as possible, and furthermore, allergic antibiotics should be selected according to drug sensitivity tests. In acute asthma attack, bronchial and pulmonary infections are induced by spasm of airway smooth muscle, inflammatory edema and exudation of mucous membrane, poor airway drainage due to obstruction of sputum and reduced immune function of respiratory tract. The presence of pulmonary infection can be clinically established based on the patient’s physical signs, blood picture and chest X-ray. Treatment should be based on the empirical selection of broad-spectrum antibiotics, sputum culture, and the selection of sensitive antibiotics according to the results of drug sensitivity tests, as well as the combination of asthma and phlegm medications, and the strengthening of care work such as turning and back-buttoning to facilitate sputum drainage. 2. Water-electrolyte and acid-base imbalance During acute asthma attack, patients often have imbalance of water, electrolyte and acid-base balance due to hypoxia, insufficient food intake and sweating, which are important factors affecting the efficacy and prognosis of asthma. Therefore, blood electrolytes and arterial blood gas analysis should be checked to detect abnormalities and deal with them in a timely manner. In addition, for patients with good cardiac function, attention should be paid to active rehydration to maintain water and electrolyte balance and to facilitate the drainage of sputum. 3.Pneumothorax and mediastinal emphysema Because gas is retained in the alveoli during acute asthma attack, the alveoli contain excessive air and the intrapulmonary pressure increases significantly, the emphysema already complicated by asthma will lead to the rupture of alveoli and the formation of spontaneous pneumothorax. When severe asthma requires mechanical ventilation treatment, the peak pressure in the airways and alveoli is too high, which also easily causes alveolar rupture and the formation of pneumatic injuries, resulting in pneumothorax or even with mediastinal emphysema. Patients with asthma should be alerted to the possibility of pneumothorax when: (1) the exacerbation occurs after a violent cough or other actions that increase intrapulmonary pressure; (2) severe dyspnea with irritating dry cough that cannot be explained by the primary disease; (3) asthma exacerbation with cyanosis, sudden coma, or shock; (4) symptoms do not resolve after regular asthma treatment; (5) reduced or absent croup on one side, or (5) Those with reduced or absent croup on one side and displaced trachea. In acute asthma attacks, the lungs are already hyperinflated and the diagnosis of pneumothorax is difficult to confirm by physical examination alone. Once the patient develops the above symptoms, chest X-ray should be performed as soon as possible. For hidden pneumothorax which is highly suspected but no change in chest X-ray, further chest CT examination can be performed to determine the location and scope of pneumothorax. In case of emergency, diagnostic puncture can be performed to clarify the diagnosis early and save the patient’s life. The key to the treatment of asthma combined with pneumothorax is to perform pleural puncture or drainage as early as possible to accelerate lung reopening, together with anti-infection, bronchodilator and glucocorticoid treatment. For tension pneumothorax, closed chest drainage should be performed as early as possible, especially in patients with asthma combined with emphysema. For tension pneumothorax and recurrent pneumothorax, surgical treatment can be considered. Mediastinal emphysema complicated by asthma is one of the important causes of acute exacerbation of asthma and life-threatening. An acute asthma attack can cause alveolar rupture and gas can enter the interstitium and migrate along the trachea and vascular endings to the hilum and into the mediastinum, causing mediastinal emphysema. Chest X-ray is the most reliable diagnostic tool, with 100% accuracy. When a mediastinal emphysema presents with respiratory distress and circulatory dysfunction, a needle can be inserted subcutaneously in the chest to vent the air by compression or a rubber tube can be placed near the superior sternal recess to drain the skin. In severe bronchial asthma and poor discharge of respiratory secretions, a low tracheotomy should be made, with a blunt separation of about 2 cm along the tracheal fascia to the posterior sternum, so that the air in the mediastinum can be discharged through the incision to reduce the resistance of the upper airway, thus reducing interstitial emphysema and adding effective measures to calm asthma, reduce the alveolar pressure and give oxygen, which can be cured in a short time if treated properly and in time. 4.Respiratory failure Severe asthma attacks resulting in inadequate pulmonary ventilation, infection, improper treatment and medication, complications such as pneumothorax, pulmonary atelectasis and pulmonary edema are common causes of respiratory failure complicated by asthma. Once respiratory failure occurs, asthma treatment is more difficult due to severe hypoxia, carbon dioxide retention and acidosis. It is important to eliminate and reduce the triggers as much as possible to prevent the occurrence of respiratory failure. When receiving a patient with an acute asthma attack, arterial blood gas analysis should be performed as early as possible. If the blood gas analysis is type II respiratory failure, the patient’s condition is serious and systemic glucocorticoids and β2 agonists should be applied as soon as possible. If the symptoms are not relieved and the pH and PaCO2 values increase progressively, early mechanical ventilation should be considered. 5. Fatal arrhythmias Fatal arrhythmias can occur during acute attacks of asthma, which may be due to severe hypoxia, imbalance of water, electrolyte and acid-base balance, or improper use of drugs. For example, if heart failure is complicated by the use of digitalis preparations, frequent use of beta agonists and theophylline preparations for bronchodilatation. Tachyarrhythmias can be induced if aminophylline is injected by sedation and the blood concentration is >30 mg/L. In the early stage of treatment, ion disorders should be actively corrected and acid-base balance should be maintained. At present, doxorubicin is commonly used clinically instead of common aminophylline treatment, which effectively avoids the adverse effects caused by aminophylline. Nebulized inhalation of β2 agonist can also effectively reduce the occurrence of tachycardia. Mucus plug obstruction and pulmonary atelectasis is a common complication of acute asthma attacks, with an incidence of about 11%. After an acute asthma attack has resolved, bronchial dendritic sputum, consisting of mucus and eosinophils, may be produced. The bronchial tubes contain mucus, and special thick and sticky mucus plugs are often found in the smaller bronchi or fine bronchi, which is one of the most important factors in the formation of the clinical syndrome of asthma. The reasons for the formation of mucus plug include: during severe asthma attack, the patient breathes with open mouth and sweats too much, which causes excessive loss of body fluids; or the use of aminophylline diuretic water loss, which makes the sputum sticky and difficult to emit; the application of sedatives and cough suppressants inhibit the cough reflex, which makes it difficult to discharge mucus; sudden discontinuation of adrenocorticotropic hormone, which causes increased bronchospasm and increased secretion. All these factors can contribute to the formation of mucus plugs in the airways, which obstruct the fine bronchi and cause pulmonary atelectasis due to the thickening of the bronchial wall, mucosal congestion, and the formation of folds by edema. The main points of treatment include: active and effective control of bronchial asthma, pay attention to the balance of water in and out, prevent the occurrence of dehydration, and take care measures such as airway drainage and active postural drainage and back tapping as soon as possible. With the above treatment, about 75% of patients can recover within 4 weeks. If the result is poor, fiberoptic bronchoscopic bronchial flushing should be applied as soon as possible to aspirate the mucus plug. 7. Atretic lung syndrome During acute asthma attacks, the bronchi are extensively blocked by sputum plugs or the β receptor function is down-regulated on airway smooth muscle due to frequent use of β agonists, such as isoproterenol, the intermediate product of metabolism of this drug, 3-methoxyisoproterenol, not only cannot excite β receptors, but also can play the role of β receptor blocking, which causes ventilation blockage due to spasm of bronchial smooth muscle. The occurrence of atopic pulmonary syndrome indicates a poor prognosis and is often life-threatening if not rescued in time. Therefore, in the treatment of patients with severe asthma, glucocorticoids and wheezing drugs should be applied early to maintain the balance of water intake and output to avoid its occurrence as much as possible. 8. Chronic obstructive pulmonary disease (COPD), pulmonary hypertension and chronic pulmonary heart disease The occurrence of COPD, pulmonary hypertension and pulmonary heart disease is related to long-term or repeated airway obstruction, infection, hypoxia, hypercapnia, acidosis and increased blood viscosity due to poor asthma control. Therefore, education of asthma patients should be enhanced to guide early and regular use of medication to avoid irreversible airway obstruction. 9, pulmonary hypertension pulmonary hypertension is a response to long-term hypoxia, the incidence of which accounts for about 3-9% of the general population in China. Pulmonary hypertension suitable treatment drugs are mainly nifedipine, captopril, dibazol, etc. Diuretics, diuretics, diuretics, hypotensive agents and corticosteroids should not be used, and beta-blockers such as insulin are prohibited. 10, tuberculosis long-term use of corticosteroids lead to the body’s immune function, can trigger tuberculosis, tuberculosis symptoms. At present, we advocate the application of fat-soluble glucocorticoids with high local activity and strong penetration, such as dipropylbemisone and fortikasone propionate, which have small doses, good antispasmodic effect and little side effects. If combined with pulmonary tuberculosis, anti-TB treatment should be strengthened at the same time with hormones, mostly using a short course of therapy for 6-8 months. 11, dysplasia and thoracic deformity Childhood asthma often causes dysplasia and thoracic deformity, the reasons for which are many, such as nutritional deficiency, hypoxemia, endocrine disorders, etc. It has been reported that 30% of children with long-term systemic use of corticosteroids have dysplasia. Other complications of bronchial asthma include allergic rhinitis, sinusitis, constipation or diarrhea and other manifestations of gastrointestinal disorders, all of which should be given sufficient attention and treated promptly once detected.