# CPAP for CO poisoning?



## InkaHootz (Nov 25, 2011)

What's the thought?

100% O2 is suppose to decrease half life of CO in the bloodstreaam to 40-60 minutes. Would pressurized oxygenation be any more beneficial?


Also.... Would CO poisoning show itself at all in ETCO2 readings? I understand the differences betwen CO and CO2, but I was just curious what the experiences in the field were. My service just recently picked up the Rad-57 and ETCO waveform. 

Thanks!


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## Cawolf86 (Nov 25, 2011)

Here our protocols for CPAP are only for resp distress. My thoughts on this are that CO doesn't effect ventilation- which is what CPAP is an adjunct for. So maybe no negative effects but not more effective than supplemental oxygen by mask?


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## JPINFV (Nov 25, 2011)

Up-To-Date doesn't cover CPAP, but does suggest hyberberic oxygen with the following indications:

CO level > 25 percent
Loss of consciousness
Severe metabolic acidosis
Signs of end organ damage

"
*Carbon Monoxide Poisoning
*The primary treatment for CO poisoning is the application of  100% oxygen and, in significant cases, the use of hyperbaric oxygen that  requires the use of a hyperbaric chamber to place the patient under two  to three atmospheres of pressure. Both treatments displace CO from  hemoglobin.

No data suggests that CPAP mimics a hyperbaric chamber, but it does  enhance the elimination of CO by providing 100% oxygen (if the device is  so designed) via a tight-fitting mask that is superior to loosely  applied 100% nonrebreather masks."

http://www.jems.com/article/patient-care/many-benefits-cpap

I'll see what more I can pull up later, but I gotta run.


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## usafmedic45 (Nov 25, 2011)

InkaHootz said:


> What's the thought?
> 
> 100% O2 is suppose to decrease half life of CO in the bloodstreaam to 40-60 minutes. Would pressurized oxygenation be any more beneficial?



Not unless you pressurize the entire patient, that is utilize hyperbaric oxygen.




> Also.... Would CO poisoning show itself at all in ETCO2 readings?



Most likely not, since most of the CO inhaled isn't going to be exhaled back out in sufficient quantity to have any appreciable effect.  Keep in mind that even in a "contaminated" room capable of inducing CO poisoning you may well be dealing with a rather dilute atmospheric concentration which leads to subtle symptoms that progressively get worse.  This is part of the reason why it can be easily mistaken for "the flu".




> I understand the differences betwen CO and CO2, but I was just curious what the experiences in the field were.



Never solely rely upon experiences in the field.  Most EMS providers are minimially educated and tend to make judgments based upon what they wish to see rather than what is actually supported by the evidence.


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## Smash (Nov 26, 2011)

usafmedic45 said:


> Never solely rely upon experiences in the field.  Most EMS providers are minimially educated and tend to make judgments based upon what they wish to see rather than what is actually supported by the evidence.



And I still maintain that it WAS Elvis in the 7-11 the other night.  I fond done seen him wiff my own eye!


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## MSDeltaFlt (Nov 26, 2011)

InkaHootz said:


> What's the thought?
> 
> 100% O2 is suppose to decrease half life of CO in the bloodstreaam to 40-60 minutes. Would pressurized oxygenation be any more beneficial?
> 
> ...



CO binds with hemoglobin so it would mask SpO2, not EtCO2.  As far as CPAP, as long as their BP can tolerate it, go for it.  It's not as good as hyperbaric therapy, but it's better than nothing.


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## Aidey (Nov 26, 2011)

It might be better than nothing, but is it better than a NRB?


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## MSDeltaFlt (Nov 26, 2011)

Aidey said:


> It might be better than nothing, but is it better than a NRB?



Yes. A NRM on a tachypneic pt will dilute the FiO2 to around 40%.  So addiing pressure to inspired O2 will somewhat "push" the CO off of the hemoglobin.  Not much, but some.


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## icefog (Nov 26, 2011)

They were at some point recruiting participants for a clinical trial intending to prove this very theory:

http://clinicaltrials.gov/ct2/show/NCT00841165

No idea what happened to the project - they haven't posted any results or updates.


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## usafmedic45 (Nov 26, 2011)

> So addiing pressure to inspired O2 will somewhat "push" the CO off of the hemoglobin. Not much, but some.



No more so than a higher flow rate on an NRB and even then with a lot of the CPAP units on the market for EMS (especially those that are just modified Downs flow generators), it is possible to get the same dilutional effect by the patient "overbreathing" the unit.


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## BLS Systems Limited (Dec 9, 2011)

As stated above, standard non-rebreathers are not very effective at delivering oxygen (you may want to Google the CHEST paper by Garcia for results).  Most CPAP units use some type of venturi to produce enough inspiratory flow to function properly and therefore have diluted FiO2 as well.  The PortO2vent CPAP device by Emergent/King and the MACS unit by Airon both offer CPAP on 100%.  The pressurized gas would increase PaO2 somewhat, but not to 2700 mmHg that you see in hyperbaric chambers (the idea is to massively increase the dissolved oxygen using pressure as the hemoglobin are tied up with CO).  In essence, delivering 100% oxygen using a better device such as BVM or specialty mask such as HiOx, FLO2MAX or O-Mask would approach the results you are seeking.

Also, CO2 detectors don't measure CO.  The RAD57 by Masimo detects and measures the hemoglobin with CO attached since it follows 8 wavelengths.  Conventional oximeters use only two, and cannot separate the oxyhemoglobin and carboxyhemoglobin, so it gives false high oxygen readings.

Finally, as an aside (since we are talking CO detection and products), anyone interested may want to check out the ClearMate CO Removal System by Thornhill Research (Note: no financial interest, but its a real cool device).  It was designed to remove CO from the body at the scene.  Pretty neat stuff but way under-promoted, especially if you have a RAD57, detect CO but have limited resources to treat during transport.


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## usafmedic45 (Dec 9, 2011)

Personally, I've always wondered if the Gamow Bags used for high altitude illnesses (HAPE, HACE and AMS) would be useful in this setting.


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## BLS Systems Limited (Dec 9, 2011)

usafmedic45 said:


> Personally, I've always wondered if the Gamow Bags used for high altitude illnesses (HAPE, HACE and AMS) would be useful in this setting.



The Gamow Bags are used in a hypobaric environment to bring the patient into a less hypobaric environment.  One website reports it blows off at 2 psi and another that states that it can go as high as 6-7 psi.  Hospital based chambers go as high as 29-30 psi and in a pinch (reportedly) 87 psi.  Still, might be better than nothing...

I was just talking with a HBO centre and they report that the Gamow Bags are becoming popular with autistic kids, who get in the bag and breath in oxygen from a mask or cannula.  I can't comment on the results with that.


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## usafmedic45 (Dec 9, 2011)

> autistic kids, who get in the bag and breath in oxygen from a mask or cannula. I can't comment on the results with that.



It's another way of bilking money out of gullible and desperate parents.  Nothing more, nothing less. It's a sickening modern version of snake oil.



> The Gamow Bags are used in a hypobaric environment to bring the patient into a less hypobaric environment.



Right.  Which means you could take a patient who was in a normobaric environment and put them into a slightly hyperbaric environment. 



> One website reports it blows off at 2 psi and another that states that it can go as high as 6-7 psi. Hospital based chambers go as high as 29-30 psi and in a pinch (reportedly) 87 psi. Still, might be better than nothing...



Yeah, the ones I have seen are able to go up to 6-8 psi I recall.  It would be conceivably possible to develop one that could go higher for this use but I have neither the time nor the serious interest in the subject to pursue it on my own.


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## mycrofft (Dec 9, 2011)

*Autistic kids like getting into squeeze boxes too. patented by Temple Grandin*







In the field, CO is hard to detect re. long term/repeated levels not leading to acute collapse. One good thing in the field I've seen, though, is that circumstances OTHER than charcoal or low level internal combustion/gasoline exhaust *tend* also to produce noxious products like CO2 and smoke. That said, field detection of CO would necessitate bringing in a monitor with you. (Hm, fix it to your ambulance litter).


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## usafmedic45 (Dec 9, 2011)

> Autistic kids like getting into squeeze boxes too.



[youtube]http://www.youtube.com/watch?v=49H0IfoILwQ[/youtube]




> patented by Temple Grandin



Yeah, I think it's a great idea to treat kids based on how you restrain cattle to castrate them. LOL


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