Pulse oximetry and COVID-19 pneumonia.

[Graham.]

What's not DIY about monitoring your own blood O2 and potentially saving your own life?

[Graham.]

It seems that monitoring your blood oxygen concentration is an excellent way of determining if you need urgent medical intervention, even when your symptoms are otherwise mild.

Simple finger-clamp pulse oximeters are available from UK sellers for under £20, but I expect that to rise, just like the isopropol I managed to buy just in time.

This Dr Levenson was interviewed on Radio 4 a few nights ago, he was very convincing.

[alan_m]

Ebay and Amazon market place is a good indication for price inflation over the past 4 weeks. I wanted a 5 litres of BAC50 to find that from the same seller the price for 1 litre is now more expensive than I paid for 5 litres at Christmas. Something I paid £112 for in January is now £170 from the same seller. Paint that goes for £18 in the sheds (but is out of stock) is near £50 on Ebay. Prices for "dust masks" and disposable gloves that used to be relatively cheap have risen and/or are now being supplied by scam operators in china and what is turning up is not fit for purpose.

[Brian Gaff (Sofa 2)]

I'd have thought that was obvious though if you are breathing and yet oxygen levels are low, then the e obvious answer is that something is bunging up the lungs and stopping the oxygen blood transfer, and also probably the co2 outward transfer as well, the result with be not very good. If these meters are so cheap would we not all have one as well as an ear thermometer, and a blood pressure device?The makers of Weather stations could easily get into medical electronics as a second string to their bow. Brian

[Brian Gaff (Sofa 2)]

It has always been thus. Some years ago I bought some excellent cd cases and moor recently bought more from the same supplier, in the same packaging but the quality was crap, with burrs and some lids did not even stay attached when opened. Chinese suppliers cutting corners again. Brian

[nothanks]

Samsung smartphones (and maybe others) have had oximeters built-in for years. The measurement app in Samsung Health is part of the "stress" test.

[GB]

Do you need some DIY advice.

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[Dave Liquorice]

Well yes but by the time you notice you're in serious trouble and in the case of Covid-19 or rather the immune systems over reaction to the virus you go down hill very rapidly.

The big problem with measuring your blood oxygen saturation is knowing what is acceptable and "normal" for you. Sat on a sofa for a few minutes and it ought to be 100%, just done a 100 yd flat out sprint it could be very low but should recover fairly quickly. In between those two examples what would be considered a "warning" level having rested for how long after excercise and what is excercise? 100 yd sprint or gentle walk up the stairs?

[Tim+]

Brian, stick to what you know.

If you?d heard the broadcast or done any reading you?d know that with Covid infection, CO2 elimitation is much less affected than O2 absorption. As it?s normally high CO2 and not low O2 that drives respiration people aren?t feeling particularly breathless, even when their oxygen levels are desperately low.

If you?d listened/read anything, this is precisely what?s being proposed/suggested.

Tim

[GB]

Do you need some DIY advice.

[Bob Eager]

Those who have Facebook (and please refrain from the usual anti-FB diatribes if you haven't, or even if you have!) might be interested in this snippet:

[Brian Reay]

Out of interest, does anyone know how these beasts work?

I assume they somehow detect the 'colour' of the blood and from that determine the O2 level - more red equating to more O2 saturation. However, that doesn't seem very precise- skin pigmentation would I assume contribute to the reading etc. I can believe you could get a relative reading - ie take a reading, have some O2 etc, and the amount of O2 in the blood increasing (hopefully), or detect a fall if the things change etc.

[Chris B]

From

The device uses light-emitting diodes in conjunction with a light-sensitive sensor to measure the absorption of red and infrared light in the extremity. The difference in absorption between oxygenated and deoxygenated hemoglobin makes the calculation possible.[6]

I have heard from elsewhere that things like nail varnish affect the readings and have to be removed before use.

[Robin]

I'd rather like to know how reliable that and other apps are. Not being into high end phones I had a very quick look and the only technical assessment I found* was not encouraging. Includes e.g.

"Samsung withdrew its claim of being able to measure oxygen saturation in May 2019 with its built-in red-light source in Galaxy phones and instead now makes the false claim that ?you can measure your oxygen saturation level by measuring your stress? (see screenshot below)."

"There is no evidence that any smartphone technology is accurate for the measurement of blood oxygen saturation. Furthermore, the scientific basis of such technologies is questionable. Oxygen saturation levels obtained from such technologies should not be trusted."

*on behalf behalf of the Oxford COVID-19 Evidence Service Team by Professors Lionel Tarassenko1 & Trisha Greenhalgh

[Brian Reay]

Thank you.

So, in broad terms, much as I speculated.

The nail varnish comment makes sense- I think some have things like metallic bits in etc which would make any kind of generic pre-calibration invalid.

It could be that, by using the red and infrared you mention, they compensate for things like variation in skin pigment between people and even variations in peoples' blood- unless there isn't much variation in the latter (I'm not thinking so much of blood colour as more subtle things like, perhaps, anemia etc.)

[T i m]

<snip>

<finds and tries it ... (thanks)> 55 bpm, 96%?

Is that good?

Cheers, T i m

[Chris Hogg]

GIYF

[Chris B]

Seems perfectly reasonable if you are currently at rest, or if you are chopping wood are very fit.

97 -99% is apparently normal for 02. <90% worrying <80% very worrying.

=================== Normal: A normal ABG oxygen level for healthy lungs falls between 80 and

100 millimeters of mercury (mm Hg). If a pulse ox measured your blood oxygen level (SpO2), a normal reading is typically between 95 and 100 percent.

==================

95% and above No evidence of impairment 80% and less Impaired mental function on average 75% and less Loss of consciousness on average

[T i m]

Hehe.

The other day and probably the first time out (anywhere) for about 15 days the Mrs and I did some laps of the local block. She did 10 laps walking and because I can't walk atm (swatting the removal of a Pyogenic granuloma, as you seem to know yer medical stuff), I cycled (on a fairly heavy cargo bike) and did 35 laps (~11 miles). I was starting to flag slightly on the upwind leg but could have carried on at a slightly slower pace but the point was 'exercise, not a casual cycle ride. ;-) [1]

There is another form of exercise we do that does get my heart going harder but I'm not going to discuss that here. <blush>

I think I'd be happy to do the test a few times over a few says and see what sort of variation there is.

Daughter just did hers and it was 73bpm and 100%?

Thanks for that Chris.

Cheers, T i m

[1] I was getting some encouragement by some locals doing work in their front garden, every time I went by. ;-)

[nothanks]

I hadn't seen that but, given the risk of litigation, I would not have thought that Samsung would make a false claim about any feature, especially one like this that is easy to test against a stand-alone, calibrated, pulse oximeter. AFAICS there is only this one report that says the Galaxy oximeter doesn't work so I will continue to use it as an indicator.