SpO2 – blood oxygen levels: what is it, how is it measured with oximeters?

SpO2 is the abbreviation for “peripheral capillary oxygen saturation,” a measure of the amount of oxygen in the blood

It is often measured using a pulse oximeter, a device that clips onto a person’s finger or earlobe and uses light to determine the oxygen level in the blood. Normal SpO2 values range from 95% to 100%. A low SpO2 value may indicate a problem with the respiratory system or circulatory system, and may require medical attention.

Also, some newer smartwatches and fitness watches have an SpO2 oximeter integrated.

How SpO2 pulse oximeters work

A pulse oximeter works by shining a light through the skin and measuring the amount of oxygen in the blood using a process called spectrophotometry. The device consists of two parts: a sensor that is placed on the finger or earlobe, and a display unit that shows the SpO2 reading.

The sensor has two light-emitting diodes (LEDs) that emit light of different wavelengths, typically red and infrared. When the light passes through the blood vessels in the finger or earlobe, some of it is absorbed by the oxygen-rich hemoglobin in the blood. The amount of light absorbed depends on the amount of oxygen in the blood.

The sensor also has a photodetector that measures the amount of light that passes through the blood vessels. By comparing the amount of light absorbed at different wavelengths, the device can calculate the SpO2 value, which is the percentage of oxygen-saturated hemoglobin in the blood. The display unit then shows the SpO2 value in real-time.

Pulse oximeters are non-invasive and painless, and they can be used to continuously monitor oxygen levels in the blood. They are commonly used in hospitals, clinics, and at home to check for signs of respiratory or circulatory problems.

Are smartwatches and fitness watches with SpO2 oximeter accurate?

The accuracy of SpO2 measurements from smartwatches varies and may be affected by a number of factors. In general, the accuracy of pulse oximeters, including those in smartwatches, can be affected by the quality of the device, the placement of the sensor, and the characteristics of the person being measured.

Some studies have found that the accuracy of SpO2 measurements from smartwatches can vary depending on the specific device and the measurement conditions. In general, the accuracy of pulse oximeters is higher when the device is used under stable and controlled conditions, such as in a clinical setting.

It is important to note that smartwatches with SpO2 sensors should not be used as a replacement for medical equipment and should not be relied upon for diagnostic or treatment purposes. If you have concerns about your oxygen levels or are experiencing signs of respiratory or circulatory problems, you should consult a healthcare professional.

Related video: MiBand 7 oximeter accuracy (detailed test, compared to a finger pulse oximeter) / MiBand 7 SpO2 meteter accuracy