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Finding the vent rate should be easy, look at a F & P 431 mask measure the DIA. of the holes and count them, drill the same in the faceplate, Use a Remstar APAP and software to check your leak rate. Use a O2 recording pulse OX to monitor your O2.

You will also have to build in a safety device to vent the mask in case the XPAP shuts down the air supply. I think the pain, exceeds the gain, but some of us are friends with pain. I have done mask experiments myself, I used 25 LPM as the bottom limit for vent rate, most masks at 30 LPM or above.

Maybe a bucket with hose attached, duct taped around the neck would work too. JIM

Goofproof wrote:Finding the vent rate should be easy, look at a F & P 431 mask measure the DIA. of the holes and count them, drill the same in the faceplate, Use a Remstar APAP and software to check your leak rate. Use a O2 recording pulse OX to monitor your O2.

You will also have to build in a safety device to vent the mask in case the XPAP shuts down the air supply. I think the pain, exceeds the gain, but some of us are friends with pain. I have done mask experiments myself, I used 25 LPM as the bottom limit for vent rate, most masks at 30 LPM or above.

Maybe a bucket with hose attached, duct taped around the neck would work too. JIM

Thanks for the excellent advice, Goofproof.

You talk about safety devices within the mask. I wasn't aware that even the standard masks came with any such sort of safety. Just the regular air one-way valve. Can you elaborate?

Most FFM have a check valve that vents the mask to the room air if the XPAP shuts down. Check the ComfortFull, it's built into the elbow XPAP air pressure forces it to seal the vent opening. It's not good enough for normal breathing but It may keep you alive until you wake up. Jim

Guest wrote:Either purchase a machine that would mimic an individual breathing on the mask that would measure the amount of expired gas that is inspired...........

Did you have such a machine in mind? I mean, you need some sort of marker that can be measured essentially instantaneously, and I can't think of how you can do that short of about a zillion dollars worth of equipment. Is that how Respironics looked at gas flows in their Total Face Mask (which seems similar in qualities to SCBA)?

Guest wrote:OR....find a research facility or hospital that would allow you to wear it while you have an indwelling arterial catheter with continous Arterial blood gas monitoring.

It would be cheaper to measure ETCO2 using an NPB70 or Novametrics Capnogard. However, since breathing is controlled principally by pCO2 levels, my guess would be that the ETCO2 trend would be the same with and without device. If pCO2 increased, ventilation would also increase. Measuring ventilation simultaneously would therefore also be essential. All this would assume that the gas purge within the mask is reasonably efficient. If it's poor, then pCO2 would progressively increase despite increased ventilation (since you'd be rebreathing CO2, the more you breathe, the worse you'd get).

It would make more sense to measure ETCO2 at various points within the apparatus to try to ascertain gas flows.

Another question would be comfort, including skin reaction, to long-term use.

As noted, a safety valve would be a critical component. Rising pCO2 becomes anesthetic in nature, so there is a point of no return where you don't wake up.

If you have COPD with pre-existing pCO2 retention, chances are that you're going to FYU pretty bad early in your experiments.

Say, it sounds like you may already have a lot of tools and equipment. If you die while doing this, can I have your stuff?

Muffy

Muffy wrote:
Say, it sounds like you may already have a lot of tools and equipment. If you die while doing this, can I have your stuff?

...... aaaahh, you get first dibs on everything!

This is the mask in question.

Machining the adapter is relatively trivial, but the matter of valves isn't.

Considering through-put of air into the device, I'm considering that it might be beneficial to have the exit valve and holes set in around the top of the facepiece, thus ensuring that gas flow must occur, positive-pressure driven, throughout a good portion of the mask. I may even diffuse the exit vents along the top to increase that benefit.

Thanks to everyone who has supplied information and safety concerns! I knew turning to this community would be the right place to start.

Now to diagram out my current masks and determine how to build effective check valves...

Hello to all
I would be interested to see what you come up with. being a vol. firefighter I also have often wondered about converting a scba mask to a cpap mask. the comfort is great, and I too have a source to obtain one of these masks. if you find a way to make it work, please post more info.
Thanks