How does a pulse oximeter work?

Pulse oximetry is a non-invasive and painless test that measures the oxygen level (or oxygen saturation level) in the blood. It can quickly detect how effectively oxygen is delivered to the limbs (including legs and arms) furthest from the heart.


A pulse oximeter is a small device that can be clipped to body parts such as fingers, toes, earlobes and forehead. It is usually used in emergency rooms or intensive care units such as hospitals, and some doctors may use it as part of routine examinations in the office.

After the pulse oximeter is installed on the body part, a small beam of light passes through the blood to measure the oxygen content. It does this by measuring changes in light absorption in oxygenated or deoxygenated blood. The pulse oximeter will tell you your blood oxygen saturation level and heart rate.

When breathing is disturbed during sleep (called an apnea event or SBE) (as can happen in obstructive sleep apnea), the oxygen level in the blood may drop repeatedly. As we all know, the long-term decline in oxygen content during sleep can cause various health complications, such as depression, heart disease, high blood pressure, diabetes, etc.

In many cases, your doctor will want to measure your blood oxygen level with a pulse oximeter,

1. During or after surgery or procedure using sedatives

2. Check a person’s ability to handle increased activity levels

3. Check whether a person stops breathing during sleep (sleep apnea)

Pulse oximetry is also used to check the health of people with any disease that affects blood oxygen levels, such as heart attack, heart failure, chronic obstructive pulmonary disease (COPD), anemia, lung cancer and asthma.

If you are undergoing a sleep apnea test, your sleep doctor will use pulse oximetry to assess how often you stop breathing during the sleep study. The pulse oximeter contains a red light sensor that emits light across the surface of the skin to measure your pulse (or heart rate) and the amount of oxygen in your blood. The level of oxygen in the blood is measured by color. Highly oxidized blood is redder, while blood with low oxygen content is bluer. This will change the frequency of the wavelength of light reflected back to the sensor. These data are recorded throughout the entire night of the sleep test and recorded on the chart. Your sleep doctor will check the chart at the end of your sleep test to determine if your oxygen levels have dropped abnormally during your sleep test.

An oxygen saturation of more than 95% is considered normal. A blood oxygen level of less than 92% may indicate that you are having trouble breathing during sleep, which may mean that you have sleep apnea or other diseases, such as severe snoring, COPD or asthma. However, it is important for your doctor to understand the time it takes for your oxygen saturation to fall below 92%. The oxygen level may not fall for long enough or not enough to make your body abnormal or unhealthy.

If you want to find out the oxygen content in your blood during sleep, you can go to a sleep laboratory for an overnight sleep study, or you can use a pulse oximeter to monitor your sleep at home.

Pulse oximeter can be a very useful medical device for patients with sleep apnea. It is much cheaper than sleep research and can reveal important information about your sleep quality or the effectiveness of sleep apnea treatment.

Post time: Jan-09-2021