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PulseOx (SpO2) sensor measurements — Parallax Forums

PulseOx (SpO2) sensor measurements

RaymanRayman Posts: 14,632
edited 2013-05-11 11:33 in Announcements
Was just playing around today and think I have it working...
Check out this thread:
http://forums.parallax.com/showthread.php/146925

Maybe it might help anybody having trouble...

Comments

  • GrandeNurseGrandeNurse Posts: 110
    edited 2013-03-24 21:28
    very nice. I noticed that some of the different pulseOX sensors (manuffac) have different pinouts and very different calibration values (different LED and sensors). Would you need to add a JUMPER header so it could be configured, so the correct DB9 pins get mapped to the analog input and digital outputs? Might also need to add a user menu item that allows them to select model/brand, thus you could invoke the correct calibration table.
  • RaymanRayman Posts: 14,632
    edited 2013-03-25 02:46
    when googling about this, I did notice that other brands use a DB9, but with a different setup.
    This Nellcor one seems to have come from a real hospital and I suspect they only use one brand, but don't know...
    Do the commercial displays really work will all the different sensors?
    Or, do you buy a Nellcor display to work with these Nellcor sensors?
  • GrandeNurseGrandeNurse Posts: 110
    edited 2013-03-25 16:50
    In the top level management layers, deals are made with the vendor sales staff that usually ends up with PRODUCT X, that only uses SENSOR X. But for those places that don't purchase millions of dollars of equipment to refurb the hospital, they are looking for the best deal. To answer your question directly, NO in the real world vendor product don't work with each others sensors. But I belive that you have a good handle on software and hardware (impressed with several things you've done) and think you have the capability to exceed the real world limits (at least until some large med company see's your work and buys you up ;). This is a NO LIMITS contest, correct?
  • RaymanRayman Posts: 14,632
    edited 2013-03-25 17:27
    I'll see if I can get my hands on any different types of sensors...

    I'm wondering how to test this thing... If I hold my breath should I see the O2 level go noticeably down?
  • GrandeNurseGrandeNurse Posts: 110
    edited 2013-03-26 16:56
    If you have the parallax med kit, then you already have a BP cuff. Pump the cuff up and you're cutting off the blood flow into your arm. It's ok for a little time (like the time to take a BP measurement), but that time duration changes if you're experienced or a new med student. During this restricted blood flow period, changes are also happening to the amount of O2 available for the pulseox to sense. DON'T hold your breath, when you wake-up you'll notice a bump on your head and no data collected because all the cables got pulled loose when you passed out.

    DON'T KEEP THE CUFF INFLATED FOR MORE THAN A MINUTE!

    Another ok test is to breath normal while you're on the tread mill and you should see a decrease in the O2 stats. Get off the mill, SIT DOWN then breath deep for a minute, the O2 percent should walk back up.
  • Invent-O-DocInvent-O-Doc Posts: 768
    edited 2013-03-29 08:27
    Interesting GrandeNurse.

    Usually SpO2 units are paired with a specific sensor or brand/family of sensors. You use the company's brand, but can choose disposable or reusable, for example. Im my experience, there was no difference in quality between disposable and reusable units, though some kids are awfully hard to get a reliable measurement on.
  • frank freedmanfrank freedman Posts: 1,983
    edited 2013-03-30 00:28
    For all youse going down the PulseOx path, have fun. With one possible new twist, most of the little things that crossed my mind regarding this technology appear to have been asked and answered, some even as you will see in this link, patented. Anyway, there is a site that is slowly gaining notice as demonstrated by notices of manual etc. no longer available on the site at the "request" of an OEM. Here is a manual (though not sure where the prints are section 9 seems to be awol) with a good amount of the SpO2 theory laid out for the biomed who will be servicing these devices.

    http://frankshospitalworkshop.com/equipment/documents/pulse_oximeter/service_manuals/Nellcor%20N200%20-%20Service%20manual.pdf

    T    here is some other good stuff there as well. I have had occasion to review one when needed.

    FF
  • RaymanRayman Posts: 14,632
    edited 2013-05-11 11:33
    After noticing obvious imperfections in my basic PulseOx circuit, I started looking around for better ideas...

    Freescale Semiconductor has some excellent appnotes on PulseOx and EKG circuits, including detailed circuit diagrams.
    They do this because their microcontrollers have integrated Instrument amps, opamps, DAC and ADC.
    So, you can implemennt with less active parts...
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