The normal value of oxygen saturation is divided into arterial blood and venous blood, which are different. The normal value of oxygen saturation of arterial blood is 95%-100%, and the normal value of oxygen saturation of venous blood is 75% or more. Oxygen saturation refers to the amount of oxidized hemoglobin in the blood, as a percentage of the hemoglobin that can be oxidized. Oxygen saturation is an indication of the concentration of blood oxygen in the blood, to understand the blood oxygen situation in the human body. It is generally monitored through finger pulse oxygen connected to cardiac monitoring and is commonly used in critical illnesses such as respiratory failure, major surgery, cranial trauma, heart failure, pulmonary embolism, and infectious shock. If low oxygen saturation indicates hypoxia in the body, oxygen treatment can be given, and the cause can be clarified as soon as possible by perfecting frontal and lateral chest films, arterial blood gas analysis, cranial CT scan or blood bacterial culture plus drug sensitivity test.