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%. 

[WCCFB]

Nobody should rely on a Fitbit for accurate information about oxygen saturation. Mine says mine averages 93 at night. I had a sleep study that found that I have nocturnal hypoxemia. My oxygen saturation is in the 70s several times an hour and when this occurs my heart rate goes up into the mid 200's. None of this shows up on the Fitbit. Now I only count on it to count my steps and give me my current heart rate. I'm upset because I almost didn't agree to the sleep study because I had put too much faith in the Fitbit  I am now on oxygen at night.

[AnnaL007]

That's amazing. So you thought all was well but in fact it wasnt. As a matter of interest, why did you agree to the sleep study? 

My levels are normally over 90 but fell to 84 last night. My heart rate variability is at 20 too..  very low. I'm in my 60s and fairly active but am concerned about this.. 

[AllnamesRtaken]

From an Internet search I just did it would seem that 80mm Hg is equal to 95% oxygen saturation level, so if your Fitbit was reading 93% then that would put you into the 70mm Hg range which is what your sleep study recorded.  Your simple multipurpose Fitbit at a couple hundred of dollars (got mine for $135) should not be equated with the accuracy of the equipment used for a sleep study... my understanding is its just giving an approximation to alert you perhaps on when to seek more accurate medical advice/measurements.  I think it did its job.  BTW, Fitbits do provide a medical disclaimer about its oxygen saturation results... it reads as such "Fitbit SpO2 is not intended for medical purposes, nor is it intended to diagnose, treat, cure, or prevent any disease or condition."  I'm no doctor but it would seem to me that if your heart rate does indeed go into the mid-200 beats per minute sounds like you're in a real medical emergency... so did your Fitbit measure your 200+ heart rates? did you get irregular heatbeat warnings (Afib), my wife's Fitbit has accurately detected her Afib in the past, which warns you to see a doctor... and that to me is the bigger concern here.  She then got referred to a cardiologist and wore a patch for 2 weeks to confirm the diagnosis.  (As an aside, my wife fixed her Afib through a diet change alone... a plant-based, whole foods diet or the PBWF diet, look it up on YouTube).

[Kristiansmom]

Yes..mine is between 90% and 94%

[JeffL01]

Here's my latest plot of Fitbit O2 (night, blue line) and my day time readings (Red line) from my hand held oximeter.  Clearly the Fitbit is all over the place while the daytime readings are tighter.  I do the daytime readings about 5-7 times a day and then take the statistical mean for the day.  There is over 1 year of data on the plot as well.  Finally, I have been calibrating my daytime readings with O2 readings when I do my regular check ups at the medical centre where they also measure my O2.  The professional oximeter has never registered am O2 level below 97% and is mostly 100%.  All this underlines the absolute inaccuracy of the off the shelf/Fitbit O2 readings.  Comments welcome.

[AnnaL007]

Thank you for this. It's reassuring for me to know that I'm not the
only one. I'll stop thinking about it now!

[Nimano]

Today’s NYT has an article with Doctors warning FDA on inaccuracies in SpO2 monitors. One study showed standard monitors are off by 1% for black skins and 1.7% for Asians (it has to do with the color of the light used) .  Fitbit is likely to be less accurate and (at least Sense 2) only provides a nightly average by sampling. It would not detect most apnea which involves short dips below 90%. 

[Nimano]

PS: the inaccuracy is not just for non-white skin tones—the concern is that the devices used in hospitals are not sufficiently tested.  Also the study done on skin tones shoo inaccuracy for clinical grade monitors.  The ones sold to consumers are not regulated as medical devices and do not even  require FDA approval. 

[FehA]

My one is reading 89% today after nights sleep. 

The highest I've got is also 93% so my Sp02 range is also between 89 to 93%. 

I was worried about it at the beginning  but do think that my oxygen is lower at night so have given up worrying about it. I wonder are we all getting the same reading.??

Although now I think of it my husbsnds reading is always 97 or 98% in morning..

Mine is Versa 2 as is hubby's so I guess I'm lacking oxygen at night.

[podkam]

Mine seems to be lower than expected too. SPO2 93% last night's range 88%-96% 

Should I worry? 

[AnnaL007]

I've given up worrying about it.

[xenaFB]

My range is 92 to 98
I wish I had this fitbit when I caught covid. I had the charge 3 which does not give you a number. A few weeks after covid I purchased a pulse oximeter and my readings would swing up and down from 90 to high 70s. I woke up with terrible headaches and migraines. I no longer get these swings, I get stable readings on my pulse oximeter. I wish I had the fitbit sense when I was experiencing these terrible swings and severe long covid symptoms.
I still have severe long covid symptoms but according to my pulse oximeter and my fitbit sense my oxygen is fine. I was also monitored when I was admitted to the hospital. They ensured my CPAP was on the right settings. No adjustments were made because settings and O2 is fine. 

[Smacha]

Yes I am getting 90 so I was researching it because I just started using this feature.

[Nimano]

I believe night time readings, while correlated, can be lower than daytime readings.  e.g.:

"Conclusions: All indicators of oxygenation assessed in this study were significantly worse at night than in the day. Because daytime and nighttime results were strongly correlated, borderline hypoxia during the day is strongly predictive of overt hypoxia at night."

https://pubmed.ncbi.nlm.nih.gov/18035240/

[FehA]

Hi there, thank you for your reply, much appreciated.
I did some research on it myself & yes the Pulse Oximetry readings are
always or nearly always much lower than proper daily readings
I got concerned when I went as low as 89%. but of late now the readings
vary between 90 to 93%.
Thank you very much for your help.
Take care.

[n8vz]

Very strange thing this morning:  checked my Versa 3 out and it said my nighttime SpO2 was 92, lower end of my normal 92 to 97 sleeping range.  Then I noticed a Fitbit update for my iPhone.  I installed, looked again, and now it said 89.  On the watch it says the range is from 88 to 89.  Never had figures that low before.  Any explanation, other than something got screwed up because of the app update? Very strange! 

[JeffL01]

Probably the new update would be my guess.  My wife got me a new Apple watch where you can do O2 measurements on demand.  Been wearing my old Fitbit and the Apple watch now foe a week or so.  will share the comparison results after a few months.  To date, some metrics are pretty close and others are way out.  O2, HRV, rest heart rate are pretty similar while number of steps and calories burned are a bit off.  Stay tuned.

[AnnaL007]

I'll look forward to hearing the results of your comparison, thanks.

[chrissyd98]

I am interested in the comparison and also which you device you prefer

Christine DiLorenzo-Smith

[MariannaMal]

I just discovered the feature and was wondering the same. Today I am at 94% and read 95% and up is considered normal, so I began obsessing about it, and it’s how I found this blog, but after reading your comments I am feeling much better.