Hypoxemia is defined as partial pressure of arterial oxygen below 60mmHg, which needs to be treated first, such as chronic obstructive pulmonary disease (COPD), bronchodilator, oxygen therapy, etc.; bronchial asthma needs to relieve bronchospasm; pneumothorax needs to be extracted by thoracentesis. 1. Chronic Obstructive Pulmonary Disease (COPD): In COPD, hypoxemia occurs due to persistent airflow limitation, ventilation dysfunction, and ventilation/blood flow imbalance. Treatment requires bronchodilators such as salbutamol, ipratropium bromide, hormonal medications such as salmeterol plus fluticasone, as well as long-term home oxygen therapy. 2. Bronchial asthma: bronchial asthma is caused by airway spasm leading to obstructive ventilation dysfunction, resulting in hypoxemia, airway spasm needs to be relieved and airway inflammatory response needs to be controlled. Commonly used medications include: glucocorticosteroids (e.g. budesonide, fluticasone inhalation, etc.), β2 agonists (e.g. salbutamol, salmeterol, etc.) and so on. 3. Pneumothorax: In pneumothorax, the negative pressure in the chest cavity becomes positive pressure, causing restrictive ventilation dysfunction and hypoxemia, which needs to be treated with oxygen intake, chest puncture and aspiration, closed chest drainage and other exhaust treatment. There are many causes of hypoxemia, it is recommended to consult the doctor in time for clarification and correct treatment to avoid delaying the condition.