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How Pulse Oximeters Work (2015)

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Re: How Pulse Oximeters Work (2015)

#51

Post by vikramkr »

alkonaut wrote: post #32
asveikau wrote: post #29

Earlier quoted context omitted.

I thought I recall reading that 94 is not dangerous or abnormal, and 90 is when you should get checked out.

This is something that is still not quite understood by doctors. I take my kid (Who has a respiratory condition) to hospital at 90. In my experience if you are in hospital with oxygen because of a respiratory illness, the oxygen would probably be given once you dip below 92-93 assuming they know you have a respiratory condition. Not because that’s the danger level but because they want to be able to tweak the O2 if y…

IIRC gasping for air has more to do with blood CO2 which is why hyperventilation is so dangerous - you can run out of oxygen without knowing it.

Re: How Pulse Oximeters Work (2015)

#52

Post by bdcravens »

wlesieutre wrote: post #18

Speculated to be included in the Apple Watch S6 this fall. https://9to5mac.com/2020/03/08/apple-watch-blood-oxygen-satu... At the time they reported that there were mentions of it in an iOS 14 leak, but it wasn't clear if it would be a software update to existing watches (somehow able to detect it with existing heartrate hardware) or in a watch hardware revision. Since it wasn't mentioned in the watchOS news at WWDC,…

For those with respiratory issues (I have CF) that would be great.

Re: How Pulse Oximeters Work (2015)

#53

Post by pps43 »

amiga_500 wrote: post #33

Does anyone know the degradation in blood oxygen levels under moderate exercise for a person who is fairly health (not athlete but slim, does regular exercise)? I had covid, so bought one of these, and I'm now building my way back to being able to jog, after months of shortness of breath. I would like to be able to understand what level my blood oxygen %, for a normal, healthy person, would drop to when say jogging.

If I really push during my 5k run, pulse oxymeter shows around 85%. Not sure how much to trust it, as soon as I stop it climbs back up. Unclear if it's due to vibrations, or my lungs catching up.

Re: How Pulse Oximeters Work (2015)

#54

Post by bdcravens »

DangerousPie wrote: post #17

Does anybody have any suggestions for how to check whether a pulse oximeter actually works properly? I bought one online from a not particularly trustworthy shop. I have never seen it show any value other than 99%. How can I figure out whether it actually does anything and doesn't just show 99% no matter what?

I have CF, so I regularly check my o2 sat levels. I actually used mine the same day as I had a checkup; I recall it being spot on. (Homedics model from Walgreens I think)

Re: How Pulse Oximeters Work (2015)

#55

Post by literallycancer »

DangerousPie wrote: post #17

Does anybody have any suggestions for how to check whether a pulse oximeter actually works properly? I bought one online from a not particularly trustworthy shop. I have never seen it show any value other than 99%. How can I figure out whether it actually does anything and doesn't just show 99% no matter what?

Hold your breath until in starts going down.

Re: How Pulse Oximeters Work (2015)

#56

Post by leetrout »

It's always interesting to me how much of a hivemind the internet has and how many coincidences there are. Just last night I dug out my cheapo pulse oximeter and checked everyone in my house to get a baseline.

I then googled how they work and read pretty much the same thing.

Re: How Pulse Oximeters Work (2015)

#57

Post by bdcravens »

The most painful thing I've experienced medically was an arterial blood draw to measure my o2 sat levels. (They numb your inner wrist with novocaine then go in with a giant needle to the artery deep in there. If it's that painful numb, I can't imagine what it'd be like otherwise.

And each time it was no more accurate than the pulse oximeter.

Re: How Pulse Oximeters Work (2015)

#58

Post by wlesieutre »

pps43 wrote: post #50
supernova87a wrote: post #37

Earlier quoted context omitted.

Does anyone know, in general, if a watch device already has a pulse measurement LED system, whether that can also serve as a pulse ox measurement? or are they different hardware requirements?

You need two LEDs (one visible, one IR) to measure oxygen level, but only one for pulse.

Apple has apparently had both since their first watch models, but only uses them for heart rate. https://www.theverge.com/2014/9/9/6126991/apple-watch-four-b...

EDIT: Apple says it uses green LEDs during workouts and IR for background measurements. Maybe it’s for energy reasons? https://support.apple.com/en-us/HT204666

Re: How Pulse Oximeters Work (2015)

#59

Post by leetrout »

dvt wrote: post #3

Went to a party last weekend where the host used a pulse oximeter (and thermometer) on everyone. Blood O2 level is apparently a leading indicator of COVID-19. Pretty cool stuff. The inner workings of it are actually quite simple as well, pretty amazing that it works as well as it does.

You may not choose to reply if you see this but I'm going to ask anyway: I'm curious if you were concerned about going to the party?
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