So here we go. I've found that Dr. Google does include a lot of information out there on how parents should use, interpret, and/or fret about using a home pulse oximeter (pulse ox) to monitor one's child's oxygen levels. I'm not professing to be an expert in this area and this is NOT a medical site, but I want to put this out there in the blososphere so that other home users can share what we know about pulse oxs with each other and hopefully get some support. Here is some general information I've found on Pulse Oximetry at home. Also, most of the links here will take you to a medical publication or an expert opinion. I'm happy to add more as you share them.
Because I am a professor, I currently think about oxygen saturation levels (ox sats) as "grades":
Less than 90%: F
One might note we are not grading on a curve here.
In any case, my perceptions are that an A or B is fine. Everyone wants an A, but a B is perfectly fine. And even a C is not all that bad, even though, personally, I freak out when Bridget starts hanging around 92%. It's the D and F grades, however, that need some attention.
HOWEVER, IT'S MORE COMPLICATED THAN THAT.
Here's the tricky part: To continue the analogy, you have to determine if the grades are a "pop quiz" (not a really big deal) or a "midterm" (which could require some remedial attention). As a high achieving student (!), I personally don't like any time Bridget gets a 92 or below. I know I said 92 is a "C" above, but it's borderline and I don't like it.
Still, a dip down to a low pulse ox should not be a cause for alarm. It's when the sats are persistent that one is supposed to worry. What does persistent mean? From what I can tell from talking to my friend, a former respiratory therapist, and our pediatrician there are many criteria. And honestly, I don't know if they should be considered together or if one is enough. First, if the ox sats stay below 90 for 5 minutes or more, that's the time one should run like a bunny to the ER. I've seen some places suggest calling 911. We live close enough to the hospital not to worry about that. Also, respiratory rate is important here and a rate above 40 absolutely means get expert medical attention NOW.
So that's the worst case scenario. What about the others? Here's where I get confused. My pediatrician says that if my daughter's ox sat hovers around 91 but occasionally (or frequently) moves up to 92, that's ok. I don't feel like that's ok. We haven't had that scenario yet, but I'm thinking that must mean it is really and truly time for oral prednisone, but probably not oxygen.
The more common scenario we've had is that Bridget dips down to 91 (or 89 or 8-freakin-6), but then bounces back up to 93 or 94. It's really hard not to panic when that happens. In fact, the first time we saw 86 is when we went to the ER, where she subsequently stayed at 99% for our whole visit. One cool thing is that our new pulse ox has an alarm on it that you can silence for 30 seconds. So I now know if I silence it 8 to 10 times, it's time to worry.
Also, now what I would do with a low number like (whether she was awake or asleep), I'd switch fingers to see if there was something funky with that finger (we often get lower readings on her index as opposed to her middle finger), and I'd likely use our old pulse ox to see if we were also getting the same reading.
Home pulse oxs have an accuracy rating of +/- 2%. And while both of ours have tracked with the ones at the hospital and doctor's offices, they still sometimes don't always agree with each other. So, if we were getting really low readings on one, I'd like to see if the other one has a similar score. Also, I no longer freak out if one has a low reading and the other one is high, because it's apparently very difficult to get a false high number---the pulse ox can't report more O2 than is actually in the blood.
So that is what I know. Persistent 91 or below on multiple fingers with multiple pulse oximters requires some attention. I am open to learning more and sharing it here. Note this is also for children only. I know squat about adults, but I'll include that information here, too, if anyone is interested. I'm also hoping this keeps us out of the hospital and off oral steroids for good. Here's hoping it helps you, too.
Update #1: Some insurance companies will pay for a home pulse oximeter. It sounds like it could be a useful avenue to explore.