Blood oxygen, or oxygen saturation, is an important indicator of the oxygen status in the body. The normal range of oxygen saturation is 95%-100%, so 97% and 100% are both within the normal range and it is not possible to compare which is better. If the oxygen saturation is persistently low, it needs to be noticed. If the oxygen saturation is below 94%, it is important to be aware that there is a lack of oxygen. The lack of oxygen is very damaging to the human body and may result in poor breathing, redness of the face and cyanosis of the lips. If there is insufficient oxygen supply to the organs of the body, it will affect the functioning of the organs and may result in emphysema and hypoxic lung disease. At this time, it is necessary to administer oxygen under the guidance of a doctor, and also actively treat the primary disease to solve the problem of oxygen deficiency at the root, and while treating, it is also necessary to monitor the blood oxygen saturation. Usually there are two ways to test oxygen saturation, one is by collecting arterial blood, which is traumatic but more accurate; the other is transdermal oxygen saturation, which only requires patients to hold their fingers for measurement, but it may be affected by pulse and skin cleanliness, and the results may have some errors, so several measurements can be taken to obtain accurate results.