monitoring EtCO2 while administering O2

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monitoring EtCO2 while administering O2

Postby northstar » Thu Oct 28, 2010 1:02 pm

The other night we had a study on a COPD patient that was on O2 at 3 lpm. Physician also wanted us to minitor EtCO2. Because we have no triple lumen cannula, the tech applied 2 cannulas. One for ETCO2 and PTAF and the other to administer the O2.
The EtCO2 was reading very low, in the teens. ABG's showed that patient is a CO2 retainer. I suspect that the flow of the O2 was diluting the sample and that's why it was reading low. When O2 was removed, monitor worked fine and read in the low 50's.
How are other labs dealing with this? How do you monitor EtCO2 while on O2? And while I am asking, how do you monitor EtCO2 while on CPAP? Do you put an adapter between the mask and hose? Some masks have the luer ports that might work. There again, does the flow dilute the sample?
I would appreciate any input and advice with this. Thank you for your help,
Jutta
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Postby linuxgeek » Thu Oct 28, 2010 6:20 pm

Yeah, that's probably not going to work out.

You could try to rig something up to sample the cannula within the mixture of the O2 bleed in, but that's going to be tricky. It might compensate for the O2, not sure.

ETCO2 on CPAP has the same problems. It doesn't work, and if it does, it's sporadic. It just leaves you guessing whether the numbers are accurate or not, which makes it useless.

You could always intubate them. j/k
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Postby respbarb » Thu Oct 28, 2010 6:28 pm

We use dual lumen cannulas for ETCO2 and O2 without problems, collecting ETCO while on CPAP is difficult . Can be done accuratley with a cannula on under the mask if you can do it without leak. Measuring it from the mask/tubing does not allow an accurate sample in our experience.
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Postby northstar » Thu Oct 28, 2010 6:47 pm

These are my thoughts as well... I promised the physician I would check into it.
I don't think our patients would appreciate being intubated :shock:
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Postby Canadian Sleep Tech » Fri Oct 29, 2010 10:25 am

I have never felt that Entital CO2 monitoring on a adult patient did anything, much prefer a TcPCO2 monitor for watching trending in CO2 levels, with the Entital CO2 the minute a patient opens their mouth readings are lost.
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Postby Rocklandish » Fri Oct 29, 2010 1:18 pm

hypothetical question this morning.

What if the Etco2 bleed out was placed near the exhaused vents on the mask rather than the intake. would this make a difference. it is something that i have been wanting to experiment with.
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Postby somnonaut » Fri Oct 29, 2010 9:31 pm

No, still way too much flow which dilutes the Co2.
Back in the day, I drilled a hole in the elbow of a respironics mask, and crazy glued in a IV tubing adapter so that it was sampling the air directly facing the patient at the elbow. This allowed the luer lock end to be outside fhe mask. Connected the ETCO2, and voila....crappy signal.
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Postby Rocklandish » Sat Oct 30, 2010 1:45 am

somnonaut wrote:No, still way too much flow which dilutes the Co2.
Back in the day, I drilled a hole in the elbow of a respironics mask, and crazy glued in a IV tubing adapter so that it was sampling the air directly facing the patient at the elbow. This allowed the luer lock end to be outside fhe mask. Connected the ETCO2, and voila....crappy signal.


Man my spelling is bad in the mormings! LOL!

Thanks Somno.
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Postby northstar » Fri Nov 05, 2010 1:55 pm

Thank you for all your replies. it was helpful, if nothing else to confirm my thinking.
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