An oxygen saturation levels chart details the oxygen saturation level of a patient and compares it to healthy levels, according to Weil Lifestyle. The oxygen saturation level is calculated based on the equation of SO2 = (23,400 * (pO23 + 150 * pO2)-1 + 1)-1, according to Cornell University.
The normal blood oxygen saturation level should be between 95 and 100 percent, notes the Weil Lifestyle. If a person has a blood oxygen level that is below 90 percent, a trip to the doctor is necessary. When a person's blood oxygen level is that low, he is diagnosed with hypoxemia, which is a persistent low blood oxygen level.
To measure the blood oxygen level, doctors perform an arterial blood gas test that involves drawing blood, reports Weil Lifestyle. Some of the most common causes of hypoxemia are COPD, emphysema, pneumonia, sleep apnea and shock. Low blood oxygen levels can also occur when a person is in an area that has a high altitude, such as climbing up in the mountains. Another cause of low blood oxygen levels is a condition known as obesity hyperventilation. Obesity hyperventilation is different, however, because the condition is caused by either a defect in the brain or from too much fatty tissue around the chest. Hypoxemia is almost always caused by a condition in the lungs, states Weil Lifestyle and Cornell University.