Oxygen saturation below 80% indicates that the body is in a severe hypoxic state, and if acute hypoxia cannot be corrected, it usually can only survive for about 100 hours. Oxygen saturation below 90% means hypoxia, and oxygen saturation below 80% indicates severe hypoxia, which may show respiratory distress, lip cyanosis, palpitation, shortness of breath, and need to sit and breathe, and may cause metabolic disorders and even acidosis. In this case, it is necessary to closely observe the changes in vital signs and actively treat the cause of the disease. If the treatment is effective and the care is proper, and the hypoxia is corrected, the patient will not die in the short term; if the treatment is not effective and the hypoxia persists, with the further decrease of blood oxygen saturation, the patient will have respiratory and circulatory failure and can die in about 100 hours. Patients with hypoxia should be kept in a semi-recumbent position with continuous high-flow oxygen, and treated according to the cause, such as diuretic treatment for patients with cardiac insufficiency, wheezing treatment for patients with bronchial asthma, and anti-infection treatment for patients with pneumonia.