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'[pic]: can you make an oxygen saturation monitor w'
2001\09\27@061033 by rad0

picon face
Hello Gents,

I've recently become aware of an O2 saturation measuring device
used by hospitals...it appears to use two led's on the top and bottom
of the index finger, which then measures heart pulse and O2 saturation,

anyone know how this works?  and can it be done with a pic?


tia

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2001\09\27@064621 by Kathy Quinlan

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Hi Rad,

No reason why it could not be done, I have a service manual for one, just
block diagrams, and theory of operation , no schematics :o(

Just need to find somewhere to park it, as the PDF is 2.5mb :o(

I can email it to anyone interested, just give me your addy :o)


Regards,

Kat.


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{Original Message removed}

2001\09\27@070739 by Dan & Vijay Marchesani

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Hi Kat,

I am interested.  Send me a file to .....danvjKILLspamspam@spam@earthlink.net

Thanks
Dan

Kathy Quinlan wrote:

{Quote hidden}

> {Original Message removed}

2001\09\27@072202 by dpharris

picon face
Hi-
This might be possible, but they arre pretty sophisticated.  You have to
compensate for the pulsatile nature of the blood flow throught the finger.  You
also have to use a specific frewy of light to detect the change in colour of the
hemoglobin in the blood.  The detectors on the market cost $800 and up.  Some
are only 1x1x1.5 inches in size.  On the other hand, medical devices have very
inflated costs because of the reliabiltiy and safety issues built into them - ie
the insurance costs lots of money.
David

Kathy Quinlan wrote:

{Quote hidden}

> {Original Message removed}

2001\09\27@112408 by Lyle Killough

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This is from hazy memories...

Pulse oxymetry is a measurement of the relative O2 carrying capacity of
haemoglobin.  For non-invasive pulse oxymetry (usually a clamp on
earlobe or fingertip), the idea is to look at haemoglobin in capillaries
close to the skin.  As the blood pumps away from the heart, it is oxygen
rich, as it returns it is oxygen depleted.  The oxy and de-oxy
haemoglobin absorb (red) light at different frequencies.

I remember nothing about the math involved here, nor the absorption
wavelengths.  I do know that there are a myriad of biomedical
engineering papers on the subject.  I looked into this long before the
advent of common internet access, and had no trouble finding info.

I also remember throwing a couple of LEDs and photo diodes together and
seeing small pulsatile waveforms on the scope.  Sorry, I don't remember
details, but I know that I didn't use anything exotic and that it wasn't
hard to go as far as seeing some signals.

Lyle

> I've recently become aware of an O2 saturation measuring
> device used by hospitals...it appears to use two led's on the
> top and bottom of the index finger, which then measures heart
> pulse and O2 saturation,
>
> anyone know how this works?  and can it be done with a pic?

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2001\09\27@171553 by Russell McMahon

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> Hello Gents,
>
> I've recently become aware of an O2 saturation measuring device
> used by hospitals...it appears to use two led's on the top and bottom
> of the index finger, which then measures heart pulse and O2 saturation,
>
> anyone know how this works?  and can it be done with a pic?


This is known as a "Pulse Oximeter".
Search under that name for lots of information.
Some years ago an issue of the superb "Hewlett Packard Journal" was almost
completely dedicated to this subject. They gave extensive information on
what is involved. HP used to be good at this - telling you how they did it
and what's involved indicates that they have done it so well that you can't
compete with them economically. Often they are right. I believe that back
issues of the HP Journal are available on the net.

The cost is not in the sensors, which are relatively simple and low cost,
but in processing the data. A substantial amount of black magic is involved.
AFAIK (based on the article) the HP sensors are throw-away items designed to
be replaced frequently in the medical environment.

The system works by using two frequencies of Infra Red. One is affected by
an absorption line in blood due to Oxyhaemoglobin and the other isn't. The
un-affected light gives a reference level of absorption allowing changes in
the other to be corrected to show only the OH level. In theory.

There is substantial craft and knowledge in fitting the results to reality
in practice. I read a paper which compared the results from a number of
different PO sets used by doctors for patients in the Andes afair. They
noted that the results from each varied under various combinations of
patient, environment and true condition. ie even real tools are only a
diagnostic guide and need to be used with care.



regards

               Russell McMahon

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2001\09\28@170627 by Rob Koteris

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Hi Kat,
Thanks for making the documentation available to those interested.
Please mail me any block diagrams you have to
EraseMEiti03924spam_OUTspamTakeThisOuTmweb.co.za.Wavelenghts used are 660nm and 940nm.
Regards,Rob


{Original Message removed}

2001\09\28@174206 by Kathy Quinlan

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face
Hi Rob,

Did I send you the manual ? If not I can send the manual, but I do not split
them, I would leave the editing to you.

I do not have any others at this stage, but if I find them I will post a
note to the list :o)

Regards,

Kat.

____________________________________________________________________________
The information contained in this email and any files transmitted with it
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to whom they are addressed. If you have received this email in error please
promptly notify the sender by reply email and then delete the email and
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----- Original Message -----
From: "Rob Koteris" <iti03924spamspam_OUTMWEB.CO.ZA>
To: <@spam@PICLISTKILLspamspamMITVMA.MIT.EDU>
Sent: Saturday, September 29, 2001 4:57 AM
Subject: Re: [pic]: can you make an oxygen saturation monitor with a pic??


> Hi Kat,
> Thanks for making the documentation available to those interested.
> Please mail me any block diagrams you have to
> KILLspamiti03924KILLspamspammweb.co.za.Wavelenghts used are 660nm and 940nm.
> Regards,Rob
>
>
> {Original Message removed}

2001\09\28@175625 by Benjamin Bromilow

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Absolutely, the pulse-ox units are great for *monitoring* patients but for
diagnostic purposes we still like getting a nice arterial blood sample for
testing. If you use PulseOx units enough you'll see a huge variation in
accuracy. Often the units will consistently measure low (ie around 90%) on
patients but when you do the blood gas the sats are okay at 95%.
So if you know that someone has good saturation as they are and want to
check that they don't desaturate then fine but for diagnostic or baseline
measurements you really need some blood- even though arterial sampling is
painful

I believe the unit takes the trough level as "finger" absorption (ie
bone/soft tissue/nail etc) and uses [peak - trough] to work out the reading.
Truly lots of black magic in it though. Often the units will display a
reasonable looking trace yet say it is poor quality. I suspect the "quality"
of the trace has little to do with the amplitude or pulse shape and more to
do with stuff we don't see on the monitor.

Ben
ps This really is too much to do with the day job!!
pps The paediatric sensors are adhesive stick on. They get replaced
frequently. Might be able to scrounge one. The adult clip on units are
usually re-used until they are held together with tape!!
pps Personally I'd rather build a "personal" ECG machine with graphical LCD
output and rythym analysis!
{Original Message removed}

2001\09\28@205248 by rad0

picon face
fascinating as usual gents...
(I mean that in a gender neutral sense, kathy)

regarding the CO blood level, can this become increased or out
of normal limits by being a heavy smoker?  or drinker?

thanks


{Original Message removed}

2001\09\28@213459 by Kathy Quinlan

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face
Hi Ben,

Ok I have just the link for you my friend, I regret that it uses a Atmel
Mega 103 (AVR), but atleast you can use it as a start point. I have a ton of
text (paper) or bioelectronics, which has sample circuits and lots of info
on theory.

I hope this link is a good start for you :o)

instruct1.cit.cornell.edu/courses/ee476/FinalProjects/s2001/jl175/EE4
76.htm

Regards,

Kat.

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The information contained in this email and any files transmitted with it
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{Original Message removed}

2001\09\29@075127 by Peter L. Peres

picon face
imho part of the black magic relies on waiting for the slower cycle caused
by respiration...

Peter

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2001\09\29@101651 by Benjamin Bromilow

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face
Absolutely!

If you do a arterial blood gas on a smoker you'll often see the CO is out of
range. Probably not enough to effect the pulse-ox dramatically- thats more
likely to be due their chronic bronchitis and/or emphysema!
It sure scares them though when you go back and casually check with them
that they do smoke. Lots of worried looks and "can you tell??".
Smoking has amazing effects on the body. At childbirth you can always tell
if the lady has smoked during pregnancy because the placenta has black tar
lumps trapped in its villous blood vessels. Similarly at post mortem you can
tell if someone smokes because of the same things (assuming there is nothing
more obvious or sinister there). Then again if it's a post mortem how
sinister can it be :). A similar thing happens if someone has lived in the
city- lots of microparticles trapped in the lungs blood vessels giving the
lungs a grey speckled appearance. But we can't all choose not to live in the
city can we!!
Saw one person in casualty (emergency room in the US), who was chain smoking
until they came in with chest pain. CO was about three times the upper limit
of normal....
Sure don't like smoking... I've worked on cardiology wards (smoking related
heart attacks!) and a respiratory ward (chronic empysema and bronchitis and
lung tumours- not sure which is worse).
Drinking shouldn't effect CO. Unless of course you drink in smokey bars and
pubs! Or spent all you money on beer and didn't fit a CO meter next to your
gas fired boiler :)

Ben

{Original Message removed}

2001\09\29@102932 by Benjamin Bromilow

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face
Oh I do like it alot.
Not sure what the output graph is showing. Doesn't look alot like a EKG but
then why were they flexing the biceps at 1Hz?? Doing EKGs is not easy at the
best of times! If they wanted to do exersize EKGs then you need mutliple
leads and lots of filtering....
Good start though :)

Ben


{Original Message removed}

2001\09\29@104846 by Kathy Quinlan

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face
Hi Ben,

I was thinking more along the lines of it has a decent isolation amp, and is
as you say a great basis, still the hard part for anything more than home
fun is getting the part manufacturer's to authorise their parts in your
designs, without those letters, if someone dies connected to your equipment
(even if it is unrelated) you have a lot of crap to wear in court.

A few years back I had to design bio feedback units for a group of psychs,
who wanted to study the patients "deepness of relaxation", part of the
design spec had it interfacing to a Macintosh SE30 (shows how long ago the
project was) I had to put multiple Isolation amp's in due to the poor design
of the Mac RS422 serial port, just to comply with regulations here in AU.
Another major area that my approval was dependent on was that I had multiple
diagrams in the user manual (and to really suck up for approval I added them
in the software too) showing where too and where not to place the pickup
leads. Basically any where in a cardiac region was out, but lower arms and
hands were fine.

Regards,

Kat.

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{Original Message removed}

2001\09\30@055223 by Rob Koteris

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Hi Kat,

I haven't received the documentation yet.Please try again at
RemoveMEiti03924TakeThisOuTspammweb.co.za

Regards,

Rob.

{Original Message removed}

2001\09\30@153545 by Arnold Chord

picon face
I would be interested.
Please send to :
spamBeGoneacnord2spamBeGonespamhome.com

Thank you
Arnold
----- Original Message -----
From: "Kathy Quinlan" <TakeThisOuTkatinkaEraseMEspamspam_OUTMAGESTOWER.COM>
To: <RemoveMEPICLISTspamTakeThisOuTMITVMA.MIT.EDU>
Sent: Thursday, September 27, 2001 3:46 AM
Subject: Re: [pic]: can you make an oxygen saturation monitor with a pic??


{Quote hidden}

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entity
> to whom they are addressed. If you have received this email in error
please
> promptly notify the sender by reply email and then delete the email and
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> not disclose or use this information in any way.
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2001\09\30@161034 by den

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Hi !

I have not followed this trace, but if you are designing a pulse oximeter I wish you the best of luck ! Very much effort has been put into noice supression and especially motion artefact supression. Currently avaliable commercial systems are very good at this !

If you are a hobbyist and want to do some experimnets, sure ! BUT if you really need oxymetric data, there are 2 (3??) vendors that supply OEM Modules. Very very much time us saved by purchasing one of these from http://www.nonin.com Look under http://www.nonin.com/OEM.html
That module gives data output as RS232 including heart rate. Stable and reliable. 200 some dollars is nothing, if you are payed by the hour.


Sven in Sweden

-----Ursprungligt meddelande-----
Från: Rob Koteris <RemoveMEiti03924TakeThisOuTspamspamMWEB.CO.ZA>
Till: EraseMEPICLISTspamspamspamBeGoneMITVMA.MIT.EDU <RemoveMEPICLISTKILLspamspamMITVMA.MIT.EDU>
Datum: den 30 september 2001 11:53
Ämne: Re: [pic]: can you make an oxygen saturation monitor with a pic??


>Hi Kat,
>
>I haven't received the documentation yet.Please try again at
>iti03924STOPspamspamspam_OUTmweb.co.za
>
>Regards,
>
>Rob.
>
>{Original Message removed}

2001\09\30@173618 by rad0

picon face
sven, sven bo ben...quit yer whinin...



----- Original Message -----
From: "Milton Medicinteknik KB, Vikingstad, Sweden"
<spamBeGonemilton.medicinteknikSTOPspamspamEraseMETELIA.COM>
To: <KILLspamPICLISTspamBeGonespamMITVMA.MIT.EDU>
Sent: Sunday, September 30, 2001 9:11 AM
Subject: [pic]: can you make an oxygen saturation monitor with a pic??


Hi !

I have not followed this trace, but if you are designing a pulse oximeter I
wish you the best of luck ! Very much effort has been put into noice
supression and especially motion artefact supression. Currently avaliable
commercial systems are very good at this !

If you are a hobbyist and want to do some experimnets, sure ! BUT if you
really need oxymetric data, there are 2 (3??) vendors that supply OEM
Modules. Very very much time us saved by purchasing one of these from
http://www.nonin.com Look under http://www.nonin.com/OEM.html

That module gives data output as RS232 including heart rate. Stable and
reliable. 200 some dollars is nothing, if you are payed by the hour.


Sven in Sweden

-----Ursprungligt meddelande-----
Från: Rob Koteris <EraseMEiti03924spamEraseMEMWEB.CO.ZA>
Till: @spam@PICLIST@spam@spamspam_OUTMITVMA.MIT.EDU <spamBeGonePICLISTspamKILLspamMITVMA.MIT.EDU>
Datum: den 30 september 2001 11:53
Ämne: Re: [pic]: can you make an oxygen saturation monitor with a pic??


>Hi Kat,
>
>I haven't received the documentation yet.Please try again at
>.....iti03924spam_OUTspammweb.co.za
>
>Regards,
>
>Rob.
>
>{Original Message removed}


'[pic]: can you make an oxygen saturation monitor w'
2001\10\01@111319 by Rob Koteris
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face
Hi Sven,

Thanks a lot for the info on the OEM modules for pulse oximetry.
Being an electronics engineer it's not easy to spend a lot of
money,especially
in the RSA, because of the unfavorable exchange rate.
My Mother(76y) suffers from COPD and requires SPo2 readings to be taken at
regular intervals. She is on supplementary oxygen for 24 hours a day. If I
could monitor some vital functions over a period of time, it could mean a
lot to her regarding her quality of live. I planned to design the oximeter
myself but with your info and the manual from Kathy I could finish my
project much sooner.
Thanks again.

Kind regards,

Rob.


{Original Message removed}

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