Oxygen saturation usually includes arterial oxygen saturation and venous oxygen saturation, with arterial oxygen saturation as low as about 90% being more dangerous and venous oxygen saturation as low as about 70% being more dangerous. Oxygen saturation mainly refers to the percentage of hemoglobin in the blood that is saturated with oxygen, and in normal people, arterial oxygen saturation is about 95% to 100% and venous oxygen saturation is about 75%. When the body’s arterial oxygen saturation drops to less than 90%, venous oxygen saturation drops to less than 70% generally suggests that the patient has hypoxia manifestations, may show chest tightness, dizziness, irritability, arrhythmia, etc., at this time you need to actively inhale oxygen, and search for the cause of the disease, treatment of the original disease. And when the arterial oxygen saturation drops below 70% may be life-threatening, if necessary, need to use ventilator-assisted respiratory therapy. If the patient’s oxygen saturation level has decreased, take immediate measures for treatment.