Low Oxygen Levels?

Earlier on, I noticed I was feeling a little panicky, perhaps a little light-headed also (something wasn't quite right). I decided to check my pulse with an oximeter built into my phone, which displays my SpO2 level, but I normally just use it to monitor my HR.

Anyway, I was shocked when I saw that my oxygen sats were at 82%, the lowest I've ever seen it (it normally reads in the high 90's, and often 100%). So this got me immediately revved up. I checked every minute or two to check on it, and it was all over the place. Between the initial 82% I recorded at 15:27 today, there were readings ranging from 90% two minutes later, then up to 97% in the same minute, then two minutes later it plummeted once more to 84%, then back up to 99% a minute later. Three minutes after that, it once again went down to 92%, then back up to 97% at 15:4, only to dramatically plummet 8 minutes later to 79%. This was the lowest reading I recorded, and my heart wasn't racing as such, ranging from 59bpm when I first noticed the low reading, to about 100 (although my HR did spike to 128 when I was in full-blown panic mode). Throughout this time, my only symptoms were panic and slight light-headedness, but I was in a state of high anxiety prior to the first reading.

What could have likely caused this very weird fluctuation of values? Could the reader itself have been giving a false recording, or was I going through some kind of respiratory breakdown? Anyone had any similar experiences?



13 Replies

  • The most likely, and almost certainly is, the fact that this is a very inaccurate way of measuring your SpO2 level. The accuracy of phones is also poor when using the camera feature to determine heartbeat. Particularily affected if your circulation is not good.

    If you are serious about wanting to check your SpO2 level you will need to buy a proper finger oximeter, preferably medical grade.

    If you are in AF the HR monitor on a finger oximeter is inaccurate and so is a wrist monitor (they can be out by 50%). If you are in persistent AF or if in paroxysmal AF and are having an episode then the SpO2 level in the oximeter can also be quite inaccurate. I was told this by a sleep apnoea consultant I saw. She also said that whilst it can be a guide it is not reliable. Also many times the medicines that are taken by AF patients will cause readings to be out or cause numbness to some fingers. She said to do the test on four different fingers and see the different results. Take the highest one. I did this on many occasions and it was surprising as to the variation between the fingers.

    I knew an oximeter was inaccurate for HB but hadn't realised that it was also inaccurate for SpO2 levels. Another interesting thing she told me is that many GPs use finger oximeters to check the patients HR because they don't know that it is an inaccurate method. It does save them time!!!! You need a proper cuff monitor or an electronic device.

  • Not just GPs, the triage nurse in A&E uses one. The first time I was taken in, the paramedics kept showing her my ECG with a HR of 200, but she wouldn't take any notice because her oximeter was reading 70bpm.

  • That is even worse!!!!! I would have thought in A&E they would have received advice training about AF and taking readings.

  • If they won't listen to paramedics there's not much hope that they'll ever listen to us.

  • Me thinks another good reason not to use these gimmicks. All they seem to do is add stress. If I was a worrier it would drive me mad wondering why my BP is much higher on one arm than the other! All I know is that it explains why ,my home readings are lower than my GPs as I am right handed (so test on my left arm) and she always uses my right.

  • Hi Bob - significantly different BPs (20%-ish) on each arm is a recognised medical condition so if this is the case you should probably have it checked.

  • I have the same bp differences in each arm. Mine are sometimes vastly different. I mentioned it to my gp the other week and she suggested going back for her to check my bp in both arms and held in various positions.

    She said I may need an angiogram not in my heart, already had one of those. this one would be to check arteries outside the heart for any blockage. She was not over concerned and said they were taught in med school that big differences were important, however experience had shown her many reasons for it that were not over concerning.

  • I totally agree with Peter. You need to buy a good oximeter. Doesn't need to be an expensive one. I wouldn't go by that phone app. Don't drive yourself crazy.

    Rubyxx 😊

  • But if you do buy one and you are in persistent AF then do NOT expect it to be 100% accurate. Do the four finger test (index and middle on both hands). Do it in the same order (eg LI, LM, RI, RM) and record each one and then use the highest.

  • Firstly get a proper oximeter and remember to use it only indoors or in total shade - direct sunlight will mess up even the best units readings.

    I suspect the numbers caused you to involuntarily breathe more deeply which then raised your SpO2, then you relaxed and it drops. I have to keep monitoring myself on plane journeys and do deep breathing exercise for about 30 seconds if it drops below 90%.

  • I know you have had plenty of useful replies to this but here's another one. I had similar problems awhile ago and all I did was put in a new battery and everything back to normal. Also tried the four finger test but got fed up with that so chose one finger and stuck with it. Hope things settling for you.


  • Any oxygen levels at those Levels you would have been blue and unconscious.

    It was definitely a machine malfunction due to the af and an incompetent machine. Please do not even think about this as a problem any more.

  • As a home health nurse, I some times get crazy readings and sometimes it has to do with poor circulation in the persons finger or the hand is cold. The pulse oximeters we use here are $30-$50 little gadgets, not 100% reliable. Make sure your battery is fresh.

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