SPO2 stands for arterial oxygen saturation, and a low SPO2 is a low arterial oxygen saturation. It is generally recognized that a normal person’s oxygen saturation should be above 94%, and below 94% is considered insufficient oxygen supply. There are pathologic, hypoxic and other causes of low oxygen saturation. 1. Pathologic causes: Inadequate pulmonary ventilation or pulmonary diffusion dysfunction, pulmonary embolism, pneumonia, obstructive pulmonary disease, heart failure, bronchospasm, airway obstruction, massive pleural effusion and other diseases may cause oxygen desaturation. 2. Physiological hypoxia: hypoxia caused by plateau reaction and excessive exercise can also lead to oxygen desaturation. 3. Other causes: for example, snake venom, drug intoxication, ketoacidosis, lactic acidosis, etc., can also cause oxygen desaturation. Before treatment, we must first find the cause of the disease, according to the condition to determine the treatment method, generally there are oxygen therapy, drug therapy, surgical treatment of these treatment means.