Like thermometers, toilet paper, and face masks before them, pulse oximeters — your doctor likely clipped one on your finger during your last annual physical and you haven’t thought of it since — have become the latest product propelled to sold-out status during the coronavirus outbreak. We spoke with Wayne Tsuang, a pulmonologist at the Cleveland Clinic, and Tufia Haddad, an oncologist and member of the remote patient monitoring team at the Mayo Clinic, about what a pulse oximeter does and whether or not you should keep one in your medicine cabinet.
“A pulse oximeter is a medical device that measures the oxygen content in the blood,” says Tsuang. “It’s an indicator of how much oxygen from the air we’re breathing into our lungs gets into the blood.” Clipped onto a fingertip, the device displays both oxygen saturation, as a percentage of red blood cells carrying oxygen, and your pulse rate. The normal range for oxygen saturation is 95–100 percent. Tsuang typically prescribes them for home use in patients with preexisting lung conditions or those who require supplemental oxygen. Because COVID-19 and pneumonia related to the infection can cause low oxygen, it’s not surprising that it’s nearly impossible to find an in-stock pulse oximeter online or at your local pharmacy.
While Haddad stresses that pulse oximetry cannot be used to diagnose COVID-19 (only a laboratory test can do so), it can be helpful in monitoring a patient who’s already been diagnosed. As part of the Mayo Clinic’s remote monitoring team, she prescribes pulse oximeters, along with other devices like thermometers and blood pressure cuffs, for patients to take measurements at home that are transmitted to doctors and nurses at the hospital. In one recent situation, nurses noticed a COVID-19 patient’s oxygen saturation dipping below normal and asked her to come into the hospital, where she received supplemental oxygen. “It’s always hard to know what the outcome would have been if we had not detected that drop in oxygen level even before she started having symptoms,” says Haddad, “but I’ve got to believe that was a small success.”
As for buying your own pulse oximeter, Tsuang recommends first asking your doctor if that makes sense for you. If so, your doctor may be able to prescribe a medical-grade pulse oximeter that’s more accurate than the typical options. Haddad explains that the devices sold in drugstores and online are not labeled for medical use, and are instead meant for athletic training (like climbers at high-altitude) or relaxation and meditation practices. “The home devices are pretty good at distinguishing when the blood oxygen oxygen levels are in the normal range,” she says. “Where they lose their accuracy is when the oxygen saturation levels fall below the normal range.” So while an at-home device can confirm normal oxygen levels in healthy people, they’re less useful in helping doctors make treatment decisions for those with low oxygen.
If you’d still like to buy one for extra assurance, the following devices have been FDA-cleared to be accurate within 3 percent for oxygen saturation levels from 70–100 percent. Just remember: Since pulse oximeters have been in high demand, the pickings are slim and products are likely to sell out.
This model is expensive but it uses hospital-grade technology and features Bluetooth for easy tracking and storing of your measurements.
Another option that offers Bluetooth tracking and a connected app.
And a smartwatch with pulse oximetry
Some fitness trackers, like the Garmin Vivoactive 4S (which this writer loves for tracking runs), feature pulse oximetry. But, as Garmin states, the Pulse Ox feature is “not intended to be used for medical purposes, nor is it intended to diagnose, treat, cure or prevent any disease or condition.” It is not FDA-cleared, either. But it still might make you feel better.
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