The new Apple Watch can be summed up in two words: blood oxygen.
The ability to measure your blood oxygen saturation – a general indicator of wellbeing – is the main innovation in the Apple Watch Series 6, which was unveiled this week and available on Friday. (The watch is otherwise not that different from the Apple watch from last year.) The function is particularly relevant for the coronavirus, as some patients in a critical condition with Covid-19 had low blood oxygen levels.
But how useful is this feature really for all of us?
I had a day to try out the new $ 399 Apple Watch and measure my blood oxygen levels. The process was simple: you open the Blood Oxygen app on the device, keep your wrist still, and press the start button. After 15 seconds of a sensor on the back of the watch measuring your blood oxygen levels by throwing light on your wrist, it will display your reading. In three tests, my blood oxygen levels were between 99 and 100 percent.
I wasn't entirely sure what to do with this information. So I asked two medical experts about the new role. Both were cautiously optimistic about the potential benefits, particularly for research. The ability to constantly monitor blood oxygen levels with some degree of accuracy could help people discover symptoms of health conditions such as sleep apnea.
"Continuous recording of data can be very useful for identifying trends," said Cathy A. Goldstein, a sleep doctor at the University of Michigan Medical Sleep Clinic who researched the data collected by Apple Watches.
For most people who are relatively healthy, measuring blood oxygen on a daily basis could be a lot more information than we need. Ethan Weiss, a cardiologist at the University of California at San Francisco, said he was concerned that blood oxygen levels could upset people and lead them to do unnecessary tests.
"It can be positive and negative," he warned. "It could keep people out of the doctor's office and at home and keep them safe, but it could also create a lot of fear."
This is important to note as smartwatches are getting new health monitoring features that give us information about ourselves that we need to figure out how to use. When the Apple Watch Series 4 introduced an electrical heart sensor for performing electrocardiograms in 2018, it was useful for people with known heart conditions to monitor their health. However, doctors cautioned that this was also a novelty that should not be skipped to conclusions or for people to self-diagnose heart attacks or other medical conditions.
And so we are back.
What you should know about blood oxygen levels
A healthy person usually has blood oxygen levels in their mid to mid 90s. When people have health problems like lung disease, sleep disorders, or respiratory infections, levels can plummet into their 60s to low 90s, said Dr. Goldstein.
When you buy the Apple Watch and have constant access to information about your blood oxygen levels, it is important to have a framework in which to think about the data. Most importantly, you have a family doctor to share the measurements with so you can relate them to your overall health such as your age and the conditions you already have, said Dr. Goldstein.
But when it comes to medical advice and diagnosis, always consult a doctor. If you notice a sharp drop in your blood oxygen levels, it is not necessarily a cause to panic and you should speak to your doctor to decide whether to have a test done. And if you're having symptoms of illness like a fever or cough, normal blood oxygen levels shouldn't be a reason to skip talking to a doctor, said Dr. Goldstein.
Have a medical professional – not your watch – create the action plan.
Monitoring blood oxygen could be more useful for people who are already known to have health problems, said Dr. White. For example, if someone with a history of heart failure has experienced lower levels of saturation in blood oxygen while exercising, that information can be passed on to a doctor who can then change their treatment plan.
The information could also be used to determine whether a sick person should go to the hospital. "If a patient calls me and says," I have Covid and my oxygen level is 80 percent, "I would say," Go to the hospital, "said Dr. Weiss.
Why should I care?
Ultimately, health data alone is not immediately useful and we need to decide how to get the most out of the information. Apple doesn't recommend what to do or how to feel about the information, any more than a bathroom scale will tell you you are overweight and give you a diet plan.
If you find the data is making you more anxious, you can just turn the feature off, said Dr. Goldstein.
But even if blood oxygen measurement sounds unconventional today, it is important to be open about how new health monitoring technologies could benefit us in the future. Both Dr. Goldstein and Dr. Weiss pointed to sleep apnea as an area where portable computers could benefit people. The disease that causes breathing problems while sleeping affects millions of Americans, but most people never know they have it.
It's a bit of a catch-22. If you've had symptoms of sleep apnea, which include lower blood oxygen levels, your doctor would order a test. But you probably wouldn't notice the symptoms while you slept, so a study would never be ordered.
The Apple Watch regularly measures your blood oxygen levels in the background, even when you are sleeping. So when we collect data about ourselves while we sleep, we may or may not discover something unknown about ourselves.
"Until we start, we don't know whether this information can be valuable or not," said Dr. Goldstein.