Pulse Oximetry Accuracy

[AragonAl]

Anyone else using the new pulse ox feature and being told that you die at night? lol! My nightly range is from 89-93%... which seems like I'm oxygen deprived at night. Of course I know that it can't be medically accurate since it's on our wrist and we move around a lot, but just wondering if anyone else is getting really low ranges. And are we all at 93% right now? I compared to 6 friends, everyone's said 93%. 

[MariannaMal]

I should add the reading on Fitbit varies for me, from 91 to 96%, but 93% on average 

[drgibson31]

This is a great explanation on how exactly pulse oximetry works. It’s a tad jargon-y but explains how it uses light and hemoglobin in blood to measure. https://medicine.uiowa.edu/iowaprotocols/pulse-oximetry-basic-principles-and-interpretation

As a medical professional myself, we do use pulse oximetry as a guideline. We remove nail polish, clean skin, and even warm up

fingers to get accurate readings but DO NOT rely on these readings for treatment. It’s a guideline of treatment and points you in a direction. Since fitbits are worn on the wrist (usually top up) you will definitively get a different measurement than say a finger tip where the blood is closer to the surface of the skin. I flipped my watch to an under position along the veins visible and got a variation of percentages. Since oxygenation changes in correlation with respiratory rate and heart rate, having lower oxygenation while sleeping is normal. The chart of variation that Fitbit provides is a better tool to examine oxygenation and should be compared to the other charts during sleep such as REM and light sleep. I hope this helps some. 
And yes during COVID, we relied heavily on pulse oximetry and SPO2 % to

see how adequately the lungs were functioning but we also use arterial blood gas measurements. Fun times. 
best of health, 

[Cassepied]

Mine says 88% no matter what it never changes. When I go to the doctor his measurement is 95 and I live in a high altitude. 

[Nimano]

It is possible that the pulse oximeter is malfunctioning. However, there is no direct comparison between measurements at the physician’s office—which are when you are awake—and Fitbit’s measurements which, as I understand it, sample while you sleep. If you are groggy in the morning rather than well rested, I would recommend a sleep study to ensure it is not apnea.

[WendyHart]

I am at 94 and was a little worried.  But now I feel better.  

[Maryt55]

I agree

[n8vz]

If you want to see inaccurate SpO2 readings try an Apple Watch.  My day readings were so inaccurate that i turned off that feature.  I have a medical-grade oximeter that we got for my mother, she had afib; and when the Apple Watch says 91, the oximeter will say 97.  

Last night i wore both to bed.  The AW said my sleeping SpO2 was 93.5 and the Fitbit said 96.  I did a little research and Fitbit gets much higher ratings for nighttime SpO2 accuracy. 

One interesting thing I found was that the AW may over estimate SpO2 for those with darker skin and underestimate it for those with lighter skin.  I’m very light skinned, as I’m half Icelandic. I don’t think this is true for Fitbit.