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 interference with the immune function of the respiratory tract. 2. Water-electrolyte and acid-base imbalance: During acute asthma attacks, patients often suffer from water, electrolyte and acid-base imbalance due to lack of oxygen, insufficient food intake and sweating, which are important factors affecting the outcome and prognosis of asthma. 3. Pneumothorax and mediastinal emphysema: As gas is retained in the alveoli during acute asthma attacks, the alveoli contain excessive air and the intrapulmonary pressure increases significantly, and the emphysema already complicated by asthma can lead to rupture of the alveoli and the formation of spontaneous pneumothorax. When severe asthma requires mechanical ventilation treatment, the peak pressure in the airway and alveoli is too high, which also easily causes alveolar rupture and the formation of pneumatic injury, resulting in pneumothorax or even accompanied by mediastinal emphysema. 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 all common triggers of asthma complicating respiratory failure. 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. 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, digitalis preparations are applied when heart failure is complicated, and beta agonists and theophylline preparations are frequently applied to make bronchial diastole. Tachyarrhythmia can be induced if aminophylline is injected by sedation and the blood concentration is >30mg/L. In the early stage of treatment, electrolyte disturbance should be actively maintained 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. 6, mucus plug obstruction and pulmonary atelectasis: mucus plug obstruction and pulmonary atelectasis are the more common complications of acute asthma attacks, the incidence is about 11%, more common in pediatric patients, the impact on the condition depends on the site and extent of obstruction. 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 causes of mucus plug formation include: during severe asthma attacks, the patient breathes with open mouth and sweats excessively, causing excessive loss of body fluids; or the use of aminophylline for diuretic water loss, which makes the sputum sticky and difficult to be expelled; the application of sedatives and cough suppressants inhibits the coughing reflex, making it difficult to expel mucus; the sudden discontinuation of adrenocorticotropic hormones, causing 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 and mucosal congestion and edema formation of folds. 7, atresia pulmonary syndrome: during acute asthma attacks, the bronchi are widely blocked by sputum plugs, or β receptor function is down-regulated on airway smooth muscle due to frequent use of β agonists, such as isopropyl epinephrine, the intermediate product of metabolism of this drug, 3-methoxyisopropyl epinephrine, not only cannot excite β receptors, but also can play a β receptor blocking effect, causing ventilation blocked by bronchial smooth muscle spasm. Once the atretic lung syndrome occurs, it suggests a poor prognosis, and untimely resuscitation is often life-threatening. Therefore, in the treatment of patients with severe asthma, glucocorticoids and wheezing drugs should be applied early to maintain the balance of in and out water and try to avoid its occurrence. 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, hypercarbia, 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 in the body, and its incidence accounts for about 3-9% in the general population in China. 10, pulmonary tuberculosis: irregular long-term use of corticosteroids lead to the body’s immune function is reduced, can induce pulmonary tuberculosis. 11, dysplasia and thoracic deformity: asthma in children 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 dysfunction, all of which should be given sufficient attention and treated promptly once detected.