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it can measure everything from heart rate to sleep quality, but one health indicator has become particularly relevant in the last two years: blood oxygen saturation. The world’s two largest manufacturers of smart watches, i they added blood oxygen monitoring to their wearable devices 2020. The COVID-19 pandemic has also made measuring vital values from home more desirable.
But the advent of blood oxygen measurements in smartwatches has also raised the question of how useful this information is without the context of a medical professional. In CNET, Vanessa Hand Orellana said she would like the Apple Watch to be able to provide more guidance that tracks blood oxygen readings. (When her level dropped to 92% overnight, she didn’t know if she should be worried.) Most smartwatches are also not approved by the US Food and Drug Administration to measure blood oxygen and cannot be used for medical purposes. is to understand how these metrics should be interpreted.
About two years later, are blood oxygen readings more useful than they were in 2020? The answer is not so simple. Medical experts say measuring blood oxygen during the day and under different conditions could reveal insights you won’t get with a traditional pulse oximeter. In addition, greater access to health data from home is also usually a good thing.
But these sensors still have drawbacks that can limit their usefulness. Smart watch manufacturers are still finding the best ways to incorporate blood oxygen measurements into broader features that give users a complete picture of their overall health.
“We know that the science behind them is still not as precise as the hospital rank in terms of the way oxygen is determined,” said Dr. Albert Rizzo, chief medical officer of the American Lung Association. “But by saying that, they have become useful from the point of view of patients, and even people who are medically ill, even healthy people, so that they can follow another vital sign.”
Breakthrough monitoring of oxygen in the blood
To understand whether measuring blood oxygen levels with your smartwatch is useful, it is crucial to first know what this metric means and how it is implemented in today’s wearables. Yours, also known as SpO2, refers to how much oxygen your red blood cells carry. It is considered an important indicator of airway health because it signals how well your body can absorb oxygen.
Oxygen saturation of the blood is usually measured throughwhich hangs on your finger. Smart watches like the Apple Watch measure this by shining light through your wrist and measuring the reflected light.
If your current smartwatch or fitness tracker can’t measure your blood oxygen level, chances are high that the next one you buy. Technology has become a staple in today’s wearables and can be found in Apple, Samsung,Garmin and Withings, among others.
Thei both measure blood oxygen levels, as does the Samsung Galaxy Watch 3 and . Fitbit devices such as Sense, Ionic and Versa smartwatches and Charge 4, Charge 5 and Luxe fitness bracelets can also measure blood oxygen levels during the night during sleep.
But most companies have not received FDA approval for their blood oxygen measurement technology. Withings is an exception; monitor blood oxygen in your ScanWatch andare both . Maxime Dumont, Withings ’smartwatch product manager, says FDA approval should make his data more credible to doctors.
“We will never replace the doctor and we have no intention of making any diagnosis by the hour,” he said. “But the results of the classes are reliable for the doctor.”
Read more: Fitbit and Apple know that their smart watches are not medical devices. But do you?
Although it was possible to take blood oxygen readings from a smartwatch before 2020, the technology experienced a breakthrough two years ago. As the pandemic floods hospitals and the health care system, there is growing interest in researching how wearable devices can track physical changes at home.
Devices from Apple, Fitbit, Garmin and Oura have been used in research examining whether wearable devices can predict disease early by measuring changes in body signals such as heart rate and temperature. A 2021 study published in Scientific Reports by researchers from the University of Sao Paulo and Centro Universitário FMABC also found that the Apple Watch Series 6 is reliable in collecting SpO2 and heart rate data in patients with lung disease in a controlled environment.
“The sheer number of people the health care system has had to deal with has made healthcare systems a little easier to experiment with these non-clinical oxygen sensors,” said Dr. Nauman Mushtaq, Medical Director of Cardiology at Northwestern Medicine Central DuPage and Delnor Hospital.
How useful are these sensors in smart watches?
While health sensors in smartwatches promise in research, some experts are not sure how often these sensors are used in everyday circumstances. “I have had several patients who have used Apple watches or similar devices to monitor blood oxygen levels,” said Dr. Ashraf Fawzy, pulmonologist and intensive care physician and assistant professor of medicine at Johns Hopkins University. “But it wasn’t as common as I thought.”
As for regular use, etc. Mushtaq sees oxygen sensors in the blood in devices likeas most useful for adding more context to overall wellness. In most cases, the average healthy person will feel physical warning signs before experiencing hypoxemia or low oxygen levels in the blood, he said.
“I don’t think that, to be honest, does anything that is clinically significant for the average person,” he said.
This does not mean that medical professionals do not see the potential. Smart watches have a big advantage over traditional pulse oximeters: their position on your wrist all day. Many smartwatches can perform background measurements of blood oxygen in addition to providing on-site checks, which means they can collect data at different times of the day.
Fitbit, Samsung,and Apple devices can passively monitor blood oxygen levels during sleep, unlike the traditional pulse oximeter used to measure on demand. Both Apple and Garmin can also measure blood oxygen levels periodically throughout the day.
But smart watches are only good at checking SpO2 levels at rest, even when scanning in the background. (Apple says its background measurements happen when the user doesn’t move, and Garmin says it reads less often if it detects large movements).
Measuring blood oxygen levels during strenuous activities would make these devices more useful because it could help doctors know whether to adjust the amount of oxygen prescribed to a patient, says Dr. Fawzy. Dr. Mushtaq also said that patients with heart failure or pulmonary hypertension can benefit from seeing if their blood oxygen levels drop during exercise.
“It can certainly help,” said Dr. Fawzy. “Because in some people, oxygen levels drop only when they are active and will be normal when they sit still.”
Health indicators are most useful when put in context, whether it’s your blood oxygen level or how many steps you’ve taken. Numbers and charts are only important when you know how to use them well.
“Finally, consumers don’t buy sensors,” said Julie Ask, vice president and chief analyst at research firm Forrester, in a previous interview with CNET. “They don’t buy data. Consumers buy what they hope will help achieve results.”
So what context do smartwatches have to provide to make blood oxygen readings more useful? Some companies are trying to answer this question by incorporating SpO2 results into other features and wellness reports in the app to better understand your overall health. Samsung, for example, includes SpO2 measurements in its owna feature on the Galaxy Watch 4 that will help you understand your sleep patterns, according to a Samsung representative. Withings uses blood oxygen levels as one of the metrics he analyzes when determining respiratory disorders, along with heart rate and movement.
Phil McClendon, manager of Garmin’s wellness product management team, could not comment on future plans when asked if SpO2 measurements would be included in other health insights. But he pointed to Garmin’s health footage as an example of the company’s approach to making health data more meaningful.
The Health Snapshot compiles a variety of metrics (including heart rate, blood oxygen, heart rate variability, respiration, and stress) to provide a high-level insight into your cardiovascular status. McClendon said that this function helps people to quantify the changes that can happen in their bodies during abnormal events.
“So maybe they have a panic attack, and they’re like‘ I want to record this thing and export a PDF to take to my doctor, ’” he said as an example.
Currently, the biggest advantage of measuring blood oxygen levels with your smartwatch is learning what is considered normal for your body. Although smartwatches are not intended for medical diagnosis, this is another signal you can send to your doctor if you are not feeling well or notice a physical change.
“Whatever device you use, compare it to your baseline, use it as a trend monitor to know that you have deviated from your baseline,” said Dr. Rizzo of the American Lung Association. “It can allow you to change what you do or seek help before you would otherwise.”