Human blood oxygen includes arterial oxygen partial pressure and arterial oxygen saturation. The normal range of human arterial oxygen partial pressure is 80-100 mmHg, and arterial oxygen saturation is 95%~99%. 1. Arterial oxygen partial pressure: that is, partial pressure of oxygen, refers to the pressure generated when oxygen molecules in arterial blood are dissolved, and its value is related to age and body position, with a normal value of 80-100 mmHg. When the partial pressure of oxygen is less than 40 millimeters of mercury for severe hypoxemia, in 40 ~ 60 millimeters of mercury for moderate hypoxemia, in 60 ~ 80 for mild hypoxemia. 2. Arterial oxygen saturation: refers to the percentage of hemoglobin saturated by oxygen, with a normal range between 95% and 99%. Reduced oxygen saturation can be caused by a variety of diseases, such as pneumonia, emphysema, heart failure and other diseases. If the patient’s blood oxygen value is too low, it is recommended that the patient go to the hospital for timely consultation and treatment.