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How Pulse Oximeters Work (2015)

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Re: How Pulse Oximeters Work (2015)

#101

Post by alecmg »

amelius wrote: post #98
ornel wrote: post #16

I measured myself at home in Mexico City and got 93%. I got kind of worried, knowing people sick with COVID-19 can have very low saturation levels without realising it. Then I remembered I was standing at about 2200 m above sea level. Lots of unexpected weirdness happens at high altutude

So was it really your oxygen saturation level, or was the measurement flawed?

even holding your breath for couple seconds will tank saturation, so pretty likely high altitude will do the same until your breathing adjusts to compensate

Re: How Pulse Oximeters Work (2015)

#102

Post by Aeolun »

elif wrote: post #88
danieltrembath wrote: post #83

The Royal Melbourne hospital in Australia is using pulse oximeters to manage COVID positive patients in their own homes. The program was setup in March this year to manage a large number of patients remotely (cost/safety). The patients take their own measurements with a pulse oximeter and digital thermometer (both off the shelf consumer items). The person is prompted via SMS and submit their vitals via website. A sof…

Thank you for sharing this. In the program guide it says a temperature reading of > 42 degrees or an oxygen saturation of < 90 are the thresholds for a MET call. Is there a basis for these specific values or are they general approximations?

Temperature higher than 42 (e.g. 43) is described on Wikipedia[1] as:

> Normally death, or there may be serious brain damage, continuous convulsions and shock. Cardio-respiratory collapse will likely occur.

It seems that that's a little bit late to consider calling the hospital?

[1]: https://en.wikipedia.org/wiki/Human_body_temperature#Fever

Re: How Pulse Oximeters Work (2015)

#103

Post by Aeolun »

doliveira wrote: post #84
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.

Honestly that's a pretty useless thing to measure. It won't be any safer than simply throwing the party without this precaution theather

I think if someone shows up with 80% saturation you can send them to the hospital? This seems valuable to me even if it doesn't do anything else.

Re: How Pulse Oximeters Work (2015)

#104

Post by Engineering-MD »

alecmg wrote: post #101
amelius wrote: post #98

Earlier quoted context omitted.

So was it really your oxygen saturation level, or was the measurement flawed?

even holding your breath for couple seconds will tank saturation, so pretty likely high altitude will do the same until your breathing adjusts to compensate

It shouldn’t effect your oxygen saturation’s at all. Respiration is driven by raised CO2 not drops in oxygen in the healthy (COPD is the classic example of where low oxygen levels drive respiratory effort)

Re: How Pulse Oximeters Work (2015)

#105

Post by Engineering-MD »

ornel wrote: post #16

I measured myself at home in Mexico City and got 93%. I got kind of worried, knowing people sick with COVID-19 can have very low saturation levels without realising it. Then I remembered I was standing at about 2200 m above sea level. Lots of unexpected weirdness happens at high altutude

I’ll be honest, a lot if the portable oxygen saturation monitors seem to report slightly out of range readings. It often picks up after a few minutes, I suspect they are calibrated poorly tbh. 94-98% is the desired range.

Re: How Pulse Oximeters Work (2015)

#106

Post by distant_hat »

Aeolun wrote: post #102
elif wrote: post #88

Earlier quoted context omitted.

Thank you for sharing this. In the program guide it says a temperature reading of > 42 degrees or an oxygen saturation of < 90 are the thresholds for a MET call. Is there a basis for these specific values or are they general approximations?

Temperature higher than 42 (e.g. 43) is described on Wikipedia[1] as: > Normally death, or there may be serious brain damage, continuous convulsions and shock. Cardio-respiratory collapse will likely occur. It seems that that's a little bit late to consider calling the hospital? [1]: https://en.wikipedia.org/wiki/Human_body_temperature#Fever

42C is 107F, it is way too high it seems.

Re: How Pulse Oximeters Work (2015)

#107

Post by httpsterio »

elif wrote: post #88
danieltrembath wrote: post #83

The Royal Melbourne hospital in Australia is using pulse oximeters to manage COVID positive patients in their own homes. The program was setup in March this year to manage a large number of patients remotely (cost/safety). The patients take their own measurements with a pulse oximeter and digital thermometer (both off the shelf consumer items). The person is prompted via SMS and submit their vitals via website. A sof…

Thank you for sharing this. In the program guide it says a temperature reading of > 42 degrees or an oxygen saturation of < 90 are the thresholds for a MET call. Is there a basis for these specific values or are they general approximations?

When internal body temperatures start nearing 40 degrees celcius, there starts to be a real risk of dehydration. Anything above that starts nearing deathly levels, generally a temperature of 42 celcius will start leading to permanent brain damage and death. So uh, if a body temp is already at 42 it starts to be a bit late going to the hospital :D

Re: How Pulse Oximeters Work (2015)

#108

Post by jacquesm »

leetrout wrote: post #56

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.

This is more a function of how many people read HN than anything else. On a population that large in a crowd of technically inclined people there's bound to be somebody who in the space of 24 hours researched how oximeters work. I read the same article a few months ago.

Re: How Pulse Oximeters Work (2015)

#110

Post by bookofjoe »

deadmutex wrote: post #23
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,…

IIRC, Fitbit has products on the market that has them. Works both on iOS and Android. https://www.wearable-technologies.com/2020/01/fitbit-adds-bl...

Retired M.D. (neurosurgical anesthesiologist) here:

Just bought a Huawei Honor 5 watch with pulse oximeter and heart rate functions: numbers seem correct and the device is fast: results in 5 seconds for O2 sat; almost instantaneous for HR.

Compare to Apple Watch HR function which takes at least 10 seconds to show result. Simultaneous side-by-side comparison of 2 devices: near identical numbers.

Even more impressive: Honor 5 costs $33 here: https://www.walmart.com/ip/HUAWEI-Honor-Band-5-Smart-Watch-B...

Superlight, compact, and comfortable. Huawei is no humbug!

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