Blood oxygen is the percentage of oxygen bound to hemoglobin in the blood as a percentage of all oxygen in the blood, and the normal range for blood oxygen is 95%-100%. If it is lower than 95%, it means that the body has a lack of oxygen, and the lower the blood oxygen indicates the more serious the lack of oxygen in the body. There is a clear relationship between blood oxygen and the amount of oxygen pressure in the blood. When the partial pressure of oxygen is greater than 60mmH2O, the body generally does not experience significant hypoxia. If the partial pressure of oxygen is lower than 60mmH2O, the human body will experience obvious symptoms of hypoxia, manifested as chest tightness, palpitations, breathlessness and blue lips. At this time, even if high-flow oxygen input is given, the patient often does not get significant improvement. Therefore, if the blood sample saturation is lower than 95%, it indicates that the organism is hypoxic, and it is necessary to find out whether it is a problem of respiratory system, circulatory system, or other systems, and give symptomatic treatment after clarification.