APAP diagnostic test with oral appliance

Rob K wrote: ↑

Fri Jul 20, 2018 6:55 pm

Any idea why the minimum pressures on the machines are like 4-5 instead of 0? I'm guessing because they are made to treat apnea, not test for it. If your treating apnea then a pressure of 4-5 is pretty low. I think most people end up higher.

Most do, though not everyone.

arthuref wrote: ↑

Fri Jul 20, 2018 7:21 pm

I wonder if it might not be safe to hack the machine to allow 0 pressure; possibly could cause breathing problems?

Sure, see that "on/off' switch? put it to 'off'... there, zero pressure.

There's a *reason* that test equipment uses nasal probes to measure breathing, and not a cpap with a long hose full of your exhaled carbon dioxide... and that's because they don't want to kill the people that are being tested.

Because living people breath fresh air, zero would mean you would have to breath the old air in the mask, and it's not even enough to fill your lungs. Jim

just stick two corks in your nostrils, and tape your mouth, that's zero...

Didn't realize there were machines that go down to 0 pressure. So some machines are able to be set to 0 pressure and still record events? I'm sure it's a bad idea to modify the machine and I'm not going to put anymore thought into.

Rob K wrote: ↑

Sat Jul 21, 2018 8:26 am

Didn't realize there were machines that go down to 0 pressure. So some machines are able to be set to 0 pressure and still record events? I'm sure it's a bad idea to modify the machine and I'm not going to put anymore thought into.

No...not that I am aware of. The lowest pressure setting possible that I am aware of with the machines that are supplied to patients is 3 cm. It depends on the brand...some brands have a 3 cm minimum and some have a 4 cm minimum.

arthuref wrote: ↑

Fri Jul 20, 2018 7:21 pm

I wonder if it might not be safe to hack the machine to allow 0 pressure; possibly could cause breathing problems?

If such a hack were possible it would essentially mean motor off, enabling you to use the inlet flow sensor to measure your inspiration and expiration to record apneas - basically like having the machine off, but still recording data. The ventilation circuit isn't a closed system, so you can breathe in air that way, with some resistance that would affect your breathing, and apnea. But, more significantly, your CPAP mask isn't going to play that game. They are designed to work with positive pressure to wash the CO2 out through small holes in the mask vent. Without PAP, much of the air you breathe in and out will be through those vent holes, so you aren't going to get a good reading from the machines inlet flow sensor. And in spite of the vent holes, zero pressure from the machine means you will be re-breathing more CO2, which will affect your results, and could cause issues like CO2 poisoning. If you have a full face (nose and mouth) mask, it will have a non-rebreathing valve (NRV) that will close off the PAP supply hose if there is no pressure, opening vents to the room for both inspiration and expiration, so you wouldn't get any flow data from the machine inlet.

The cheapest option for what you want to do is the "CONTEC RS01 Respiration Sleep Monitor." It's a $300 wrist-worn recording pulse ox monitor with a flow measuring nasal cannula. It does not, however, have thoracic effort bands, so it can't distinguish obstructive apnea from central apnea. So if you are going to hack, you probably need to give up on using the PAP machine to record your non-PAP results via the PAP supply and concentrate on other ways to record nasal inspiration.

By the way, I'm not the one interested in hacking my CPAP, I was responding to another post that brought that issue up:

I wonder if the machine would go to 0 with modification. I've done electronic repair for quite a few years. Day dreaming about modifying the xpap. Don't try this at home. lol

The cheapest option for what you want to do is the "CONTEC RS01 Respiration Sleep Monitor."

Someone else recommended that to me the other day; I'm looking into that. Thanks.

Pugsy wrote: ↑

Sat Jul 21, 2018 9:15 am

Rob K wrote: ↑

Sat Jul 21, 2018 8:26 am

Didn't realize there were machines that go down to 0 pressure. So some machines are able to be set to 0 pressure and still record events? I'm sure it's a bad idea to modify the machine and I'm not going to put anymore thought into.

No...not that I am aware of. The lowest pressure setting possible that I am aware of with the machines that are supplied to patients is 3 cm. It depends on the brand...some brands have a 3 cm minimum and some have a 4 cm minimum.

That's what I thought. I went back and realized I didn't understand Paleriders post the first time though. Thought he meant the pressure can be set to 0 which is not the case.