Blood Oxygen Levels: What’s All the Hype About?

September 28, 2020

Clinical Contributors to this Story

Adrian Pristas, M.D. contributes to topics such as Sleep Medicine.

There has been a recent spike in sales for pulse oximeters, the small device used to measure the level of oxygen in your blood. Apple also just announced that the new Apple Watch Series 6 comes with a blood oxygen sensor and app. So, why is the spotlight on this health metric?

To get the inside scoop on blood oxygen levels and pulse oximeters and why there’s growing interest in both, we spoke to Adrian Pristas, M.D., pulmonologist and corporate medical director, Centers for Sleep Medicine at Hackensack Meridian Health.

Q: What does “blood oxygen level” mean?

Dr. Pristas: “Blood oxygen level” describes the amount of oxygen you have circulating in your blood. Our bodies need oxygen to function. Oxygen enters the body through the nose and mouth and passes through the lungs into the bloodstream. Once in the bloodstream, oxygen helps replace cells that wear out, provides energy for our bodies, supports the way our immune system functions and more. Low blood oxygen levels indicate that there may be an issue with your lungs or circulation.

Q: Why is there increased interest in blood oxygen levels?

Dr. Pristas: People started to buy pulse oximeters to measure blood oxygen levels at home when they learned that low levels could be a sign of COVID-19. Shortness of breath is a well-known symptom of COVID-19, but it’s not always easy to detect. Some thought this device could be a tool to help self-assess for signs and symptoms. There have also been reports of “silent hypoxia” where peoples’ oxygen levels are dangerously low, but they don’t necessarily experience shortness of breath.

Q: What’s a normal blood oxygen level, and when should I be concerned?

Dr. Pristas: If you’re using a pulse oximeter to measure your blood oxygen level, a normal reading is a Sp02 level that’s between 95 and 100 percent. However, this may vary for people with certain medical conditions, such as lung disease. Speak with your doctor to determine what ‘normal’ is for you and keep in mind that while these at home devises are handy and non-invasive, they are not always 100% accurate. In fact, Apple says its new blood oxygen feature should only be used for general fitness and wellness purposes and should not be used to diagnose, monitor or treat any medical conditions. Other tests, performed by health care providers, include blood draws or breathing tests to accurately measure blood oxygen levels. If your Sp02 is below 95% you should consult with your health care provider.

Q: Can a pulse oximeter detect COVID-19?

Dr. Pristas: A pulse oximeter cannot detect COVID-19, however, it can help you monitor for signs and symptoms associated with the virus. Having a low blood oxygen level could be a sign of COVID-19, but it can also be a sign of other health issues that need to be discussed with your health care provider. Either way, if you are monitoring your blood oxygen levels at home with a pulse oximeter, contact your health care provider if your Sp02 drops below 90-95%.

Q: How does a pulse oximeter work?

Dr. Pristas: Using a pulse oximeter is painless. The small device simply clips on to your finger, and beams of light measure the amount of oxygen in your blood, as well as your heart rate. The small beams of light analyze the color and movement of your blood cells. Dark red blood cells indicate a lack of oxygen, while bright red blood cells indicate the right amount of oxygen. If 95% of the blood cells are bright red, while 5% are dark red, your Sp02 would be 95%.

You can also attach a pulse oximeter to your toe, earlobe or nose, but it is commonly used on your finger. Once the Sp02 reading appears, you can remove it.

Q: Should I monitor my blood oxygen levels at home?

Dr. Pristas: There are some scenarios when your doctor might recommend you monitor your blood oxygen levels at home. If you have an underlying health condition, like heart or lung disease, or you are in the process of recovering from COVID-19, it could be helpful for you to keep an eye on your blood oxygen levels. However, if you do choose to monitor from home, talk to you doctor first about how to properly use the device, understand your reading and interpret the results. For example, if your hand is not steady during the reading you could see varying saturations from a faulty reading.

If you’re otherwise healthy, it’s not necessary to have a pulse oximeter or any other device to monitor your blood oxygen levels at home. If you’re unsure, ask your doctor for personal advice.

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The material provided through HealthU is intended to be used as general information only and should not replace the advice of your physician. Always consult your physician for individual care