Oxygen levels fluctuate within seconds on pulse oximeter

July 26, 2023 6:35 AM

Within second my levels go from 91 to 94 from 94 to 96 to 97 and down to 94 again. I've done this with 2 separate oximeters and both show the same thing. IKYNMD, have been to several cardiologists. The issue of the oxygen levels fluctuating have not been addressed as there is nothing emergent. My question to hive mind is - technically, why is this happening and could it be due to diastolic dysfunction?
posted by watercarrier to Health & Fitness (9 answers total)

I think this is pretty typical? You can change your actual oxygen levels by breathing differently (holding your breath, breathing more deeply or shallowly, etc.), and you can affect the reading by e.g. tensing your finger.
posted by mskyle at 6:46 AM on July 26, 2023 [1 favorite]

Does your oximeters have a way to see signal strength such as heartbeat line? It should look like regular waves and not choppy at all. If it is choppy the singal is being disrupted and the reading is poor. They can be notoriously fickle with movement , cold hands and skin color so any of those things may contribute.


If you are experiencing symptoms of shortness of breath, look blue, and or symptoms of distress that aligns with those lower readings and you are concerned about your health, please just go to the emergency room. Readings in the low 90s at rest are not good, and you may need to have supplemental oxygen at home. So go to the ER and get that checked out if you haven't.
posted by AlexiaSky at 6:49 AM on July 26, 2023

You mean a home device? These things do not have anywhere near the accuracy or precision your question seems to imply:

" if an FDA-cleared pulse oximeter reads 90%, then the true oxygen saturation in the blood is generally between 86-94%."

https://www.fda.gov/medical-devices/safety-communications/pulse-oximeter-accuracy-and-limitations-fda-safety-communication
posted by SaltySalticid at 6:58 AM on July 26, 2023 [7 favorites]

Pulse oximeters are not terribly accurate and calibrated machines, I would not think twice about changes <10%.
posted by so fucking future at 6:59 AM on July 26, 2023 [2 favorites]

88 % percent is during a walking test, not just at rest for Medicare to cover.
posted by AlexiaSky at 10:39 AM on July 26, 2023

Also at rest, for continuous home O2.
posted by shiny blue object at 10:51 AM on July 26, 2023

Disclaimer: I'm a physician but this is not meant as medical advice, just some thoughts about home pulse oximeters.

So one common reason for wildly fluctuating readings is a crappy meter! Or two crappy meters. I have bought quite a few for family and friends since the start of the pandemic and have recently got crappy ones from the same seller I used to buy from before.

Next, weak signal- cold hands, nail polish, irregular pulse, bad fit (due to finger size).

Next, right after switching on, those first ten seconds the meter is just warming up so to speak. Wait until there is a steady zigzag line and then take a look.

As for how to interpret the reading, depends on your diagnosis and why you're taking the measurement. Some folks with chronic lung disease for example have a lower baseline. The target to qualify for home oxygen is not the same as a healthy or acceptable value in a person without a chronic lung condition. If there's a reason to measure your oxygen saturation beyond curiosity you should talk to your doctor. But in general, the more rapid and especially the more fleeting the changes (ie seconds, changes in both directions) as opposed ro a sustained trend) the more likely the signal quality is the issue.
posted by M. at 1:32 PM on July 26, 2023 [3 favorites]

Response by poster: So, just to make this a bit clearer, up until a few weeks ago my stats were fine. 99%-98%. What did happen in the interim was that I became slightly anemic and was dx'd per echo with hyperdynamic ventricular output. The meters are fine - one is the same one I've been using. I did find myself from time to time pursing lips to breathe a bit better. It's been very hot were I am, and taking the heat into account. But because of all else that's been going on, am just a tad concerned, hence the question.
posted by watercarrier at 10:05 PM on July 26, 2023

We have a clip-on-finger pulse oximeter and it generally flickers up and down a few percentage points for all three of us in the household. I don't know if it's the machine not reading perfectly, or our actual levels fluctuating, but it seems pretty normal for us.
posted by TheophileEscargot at 7:45 AM on July 27, 2023