SpO2, also known as oxygen saturation, is a measure of the amount of oxygen-carrying hemoglobin in the blood relative to the amount of hemoglobin not carrying oxygen. It is a noninvasive, pain-free way of measuring the oxygen in a persons blood. Oxygen saturation is an essential element of patient care, as hypoxemia can lead to many acute adverse effects on individual organ systems, including the brain, heart, and kidneys. A pulse oximeter can measure oxygen saturation, and it is a noninvasive device placed over a persons finger. The normal SpO2 range for a healthy individual is between 96% to 99%, but high altitudes and other factors may affect what is considered normal for a given individual. A normal SpO2 level is vital to maintaining the health of all tissue in the body, and very low levels of SpO2 can result in very serious symptoms. Pulse oximetry is also used to check the health of a person with any condition that affects blood oxygen levels, such as sleep apnea, and to see if a ventilator is needed to help with breathing or to see how well it’s working.