Wearables have come a long way in the past decade. The days of simple step tracking are gone, replaced by a slew of new and sophisticated health sensors. One of the latest sensors that is growing in popularity is the pulse oximeter. It’s making its way onto more and more fitness trackers and smartwatches by Garmin, Fitbit and others. But what is the pulse oximeter and why is it important? Allow us to explain.
What is a pulse oximeter?
Pulse oximeters, often called SpO2 sensors on wearables, are used to measure blood oxygen levels or the saturation of oxygen in your blood. In the medical field, pulse oximeters are usually small devices that resemble a clip. They can be attached to a finger, toe, and sometimes an earlobe to painlessly measure blood oxygen levels. Both medical and wearable oximeters use light to do so.
Typically, a pulse oximeter features two LEDs with different light wavelengths — one red and one infrared. This is because absorption of light differs between blood that has normal levels of oxygen and blood that is lacking oxygen. Oxygenated blood absorbs more infrared light, while deoxygenated blood allows more of it to pass through. This allows pulse oximeters to quickly and non-invasively detect oxygen levels and measure how well oxygen is carried to the extremities.
However, not all wearable pulse oximeters are made equal. Pioneering devices equipped with the sensor like the Withings Pulse Ox required you to place your finger on the back of the device for measurement. Most others can be used while the device is still on your wrist, but they require you to hold still for a number of seconds for a single on-the-spot check. However, recent watches and fitness trackers usually have sensors that provide pulse ox sleep tracking too.
Nevertheless, wearable sensor data shouldn’t be used for self-diagnosis, especially if the tracker or smartwatch does not have an FDA clearance. It can still be a great tool for potential detection of health issues, but it needs to be followed up by an examination and diagnosis from a medical professional.
What is it used for?
Like any other wearable health sensor, the primary function of a pulse oximeter is to gather health data and notify you if you something is out of the ordinary. The first thing to know is the normal blood oxygen saturation rate. It sits at around 95% for healthy individuals, although lower rates are both possible and normal. However, if you consistently get readings below 90%, it might be time for a visit to the doctor. They can double check the accuracy of the readings and recommend next steps.
A pulse oximeter is an essential sensor for alpine enthusiasts.
A fitness tracker equipped with a pulse oximeter can also come in handy if you are upping your exercise game. This is because blood oxygen saturation readings can be used to interpret how well you handle increased activity. If you are overdoing it your levels might drop low, signaling you to take things a bit easier. It is also an essential sensor for alpine enthusiasts who climb to high elevations where the air is thinner.
Finally, since many new trackers now feature pulse oximeters that provide tracking throughout the night, the sensor can be used to detect early signs of sleep apnea. Sleep apnea is a serious sleep disorder which causes those affected to stop breathing for short intervals during the night. Sufferers often snore and don’t feel rested even after a full night’s sleep. More importantly, leaving the disorder untreated can result in other more serious health issues. This is why a smartwatch with a pulse oximeter can be beneficial for early detection.
Trackers with pulse oximeters
If you are convinced that you need a wearable with a pulse oximeter, we have good news! There are a number of fitness trackers and smartwatches that already sport the SpO2 sensor. Garmin is one of the manufacturers that has incorporated a pulse oximeter in many of its recent wearables, including the Garmin Vivosmart 4, the Garmin Venu, Fenix 5X and 6X, as well as most of the Forerunner running watches.
Withings is another brand that has been favoring the pulse oximeter. Its first device to feature it was the Withings Pulse Ox, but the brand has made big steps with its latest ScanWatch, which it showed off at CES 2020. It will be able to track oxygen saturation levels throughout the night and is focused on sleep apnea detection. Just like many others, however, the device still hasn’t been cleared by the FDA yet (though it’s slated to be cleared in 2020).
Fitbit, on the other hand, has had the light-based SpO2 sensors on some of its devices for quite some time. The Ionic, Versa, and Versa 2 watches sport the sensor, as does the Charge 3 fitness tracker.
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