If you've ever had to be rushed to an emergency room, been admitted to a hospital for any type of treatment or procedure, or even watched television shows about emergency medicine, you've seen SPO2 monitors in action.

SPO2 stands for Oxygen Saturation Level.

These levels are monitored by a device that is attached, usually to the right index finger, to measure blood oxygen levels in the body.  This device - called an SPO2 monitor - gives results measured by percentages. On one side of the monitor has an infrared light and the other side houses a sensor.

The monitor is then attached to a computer which receives, records and projects this percentage data. A normal SPO2 is usually 95 to 99 percent. SPO2 percentages go up or down depending on how well a patient is breathing and how well blood is being pumped throughout the body.

This measurement is vital to patients being treated for heart-related or breathing conditions or disorders to establish if additional oxygen is needed - and how much is needed - during treatment.  It is also very useful in recording a patient's pulse rate.


Well oxygenated blood leaves the lungs, which is then circulated by the heart through the arteries (arterial blood). As the organs use the oxygen, the deoxygenated blood then travels back through the veins and returns to the lungs to become oxygenated once again (venous blood).

The oxygenated blood absorbs infrared light and allows red light to pass through, while deoxygenated blood absorbs the red light and allows infrared light to pass through. Since saturation levels must be taken from the arterial blood as opposed to the venous blood, the SPO2 monitor calculates the ratio of red to infrared light to provide the oxygen levels.

SPO2 monitors are a vital way to monitor a patient's blood levels to ensure they are receiving and circulating enough oxygenated blood to sustain life and help in the treatment process.