Carbon Dioxide and SP02 monitors

[BushyFromOz]

Greetings earthlings.

Quick one, C02 binds to heamoglobin but not to the Fe molecule like 02 does. Even so, does this provide false postives when the IR light passes through for SPO2 sensors?

I know the vast majority of C02 is tied up in carbonic acid, with a bit dissolved in plasma and a bit tied to heamoglobin, but could / would it cause false readings in acidotic respiratory compromised patients where PC02 increases from buffering?

random 1 am thought

[Kiwiology]

We need to start getting you more bed time valiums ...

The short answer is no; dyscarboxaemia does not affect SpO2 but will obviously affect ETCO2

I will get some kip and figure out exactly why and get back to you

Oh look 3am valiums mmm num nums ...

[Arctickat]

Hmm, I sounds like you're confusing CO and CO₂ a little bit because CO will bind to Haemoglobin and mess up the SP0₂ Sensor.

[Kiwiology]

Wait, is dyscarboxaemia a word? Hmmmm ....

Oh look inventing word valiums num nums

[BushyFromOz]

Hmm, I sounds like you're confusing CO and CO₂ a little bit because CO will bind to Haemoglobin and mess up the SP0₂ Sensor.

God, you know what, it sounded good in my head at 1 am but after some a sleep and a coffee or two i realise the question is just retarded. How embarrassing.

I just read some article about C02 binding to heamoglobin writen by some chemist, basically saying the current model was wrong and that C02 dissolves in the cytosol RBC's and doesn't attach to the proteins on the HB molecule as is the current model. But it doesn't change the fact that C02 won't change the IR frequency of the SPO2 sensor.

[Eydawn]

Yeah... you had a 1am funny.

CO binds to the same binding site as O2, thereby showing the RBC as "saturated" (increasing pigmentation) and causing a false high reading.

CO2 binds to hemoglobin and doesn't affect saturation, thereby having no effect on SpO2 reading. Hence why you can have someone who has plenty O2 but is retaining CO2 and thereby in deep doo-doo as far as their acidosis/alkalosis balance goes...

Wendy

CO EMT-B

RN-ADN Student

[BushyFromOz]

Oh look 3am valiums mmm num nums ...

It aint workin, send me something stronger

[Kiwiology]

It aint workin, send me something stronger

Not for you

*smacks Bushy's hand

You know that reminded me of the last time I got tied up in bed .. hmm, excuse me for a bit, I am going to be over there in that other Chrome tab mmmmk

[BushyFromOz]

Not for you

*smacks Bushy's hand

You know that reminded me of the last time I got tied up in bed .. hmm, excuse me for a bit, I am going to be over there in that other Chrome tab mmmmk

Yeah, i heard that they stole it and put it in that sherlock holmes movie with Robert Downey Jr in it

[chbare]

Can you link the article, I'd like to see this new concept as it puts forth a very different hypothesis than our current model.

Regarding the sPO2, I pretty much have to parrot everybody else. It's a good question and the answer is complex, but it's basically because of electrons. Electrons in a certain arrangement will only absorb a certain, discrete amount of energy. With an electron, you either have the right amount of energy or you don't. There's no half arseing here. Certain electrons are in a very specific configuration when it comes to oxyhaemoglobin and will absorb light at very specific wavelengths. Remember, wavelength of light tells us the energy. The red and infrared light used in pulse oximeters has a relatively long wavelength and thus is at lower energies. Certain molecular complexes absorb light at other wavelengths and we can make use of this in other modalities such as co-oximetry.