Which Res? Urgent!

[Sleepster]

and then I got tired of reading about it.

Don't blame you. Thanks, though, for clearing that up.

I plan to figure out a way to connect a manometer to a CPAP hose and measure the pressure as I breathe.

[vsheline]

Thanks for confirming that I'm not off my rocker. I knew I had reasons to think that the maximum pressure relief was 1.5cm.

And yet, that chart I dug up earlier tonight from some very old Resprionics stuff does seem to run counter to all these descriptions about Flex.

well, very old, perhaps it changed...

I read a white paper last year which was posted on a Respironics website (maybe written years earlier, not sure) which described the amount of pressure relief as approximately one cm H2O per step, but emphasized that it was Flow based and so could be more or less. Tonight I searched some of the Philips Respironics websites and googled to try to find it again, but did not find the exact same paper.

Tonight I found the paper below, published in Sleep Diagnosis and Therapy, Jan-Feb 2009 (which was not very long ago), with a figure from Respironics on page 22 showing "Simulated C-Flex Breath" with varying pressure relief of 2 or 3 cm H2O, and this was with a C-Flex setting of 2, not 3:
http://www.sleepdt.com/_journal/v4n1/pdf/SDT-20-25.pdf

Of course, an issue with simulations is: Garbage In, Garbage Out. If the assumed Flow is too large, the resulting pressure relief will be too large.

[vsheline]

Is their new machine some kinda break through in technology that left Resmed S9 Autoset in the dust?

I realize everyone is busy with holiday, but shoot me a quick opinion in this thread to help me make my decision. I gotta face the music Monday, and am very nervous.

PS, the cpap store actually told me that they CAN'T give me a resmed because my pulmonary doc has an outstanding order to only issue respironics. This got my Irish up.

Hi cowboy1970,

If you prevail upon the doctor to prescribe an S9 AutoSet with heated hose, you will have a spare of everything: Power Adapter, power cord, Blower, humidifier, water tank, etc. Only one type of air filter to buy. The simplicity would be valuable.

Personally, I think the type of pressure relief (EPR) offered on ResMed machines is more comfortable. But I think EPR works best on an APAP machine and requires the Pressure to be raised if using EPR on a fixed-pressure CPAP machine which is unable to automatically raise its pressure whenever needed.

Take care,
-- Vaughn

[diamaunt]

and then I got tired of reading about it.

Don't blame you. Thanks, though, for clearing that up.

I plan to figure out a way to connect a manometer to a CPAP hose and measure the pressure as I breathe.

perhaps an oxygen port,and a hose loop in that with water in it, (I'd think that would be the easiest home made one.)

bought manometers come with a T fitting, I believe.

I'd be interested in hearing the results.

[Sleepster]

I have access to lab equipment. It will be interesting trying to rig something up. A water manometer will be easy enough to make and I will need to experiment with tube diameters, I think, to get a fast-enough response time. In other words, when the pressure changes quickly will the manometer reading change fast enough to capture it? That Bi-Flex pressure dip happens rather quickly and we are trying to find its minimum value.

I wonder if this information is available in the pressure graphs generated by EncoreBasic or SleepyHead. So far I haven't been able to find it.

The electronic pressure sensors that I have are very likely not sensitive enough to measure fractions of a centimeter of water. Perhaps someone who takes CPAP machines apart might be able to figure out how the pressure sensors work. I might then be able to connect one to a computer interface and use the software I have to graph the data.

[diamaunt]

Perhaps someone who takes CPAP machines apart might be able to figure out how the pressure sensors work. I might then be able to connect one to a computer interface and use the software I have to graph the data.

jedimark was talking about experimenting with something on this list:
http://www.freescale.com/files/sensors/d...PX5010.pdf

the pressure sensor in the s9 is a smt chip that's vented into the airflow near the outlet.

there's no pic of the PRs1 pressure sensor in the service manual I've got, and I've not taken one apart, the service manual indicates they're all clustered right by the outlet.

[Sleepster]

jedimark was talking about experimenting with something on this list:
http://www.freescale.com/files/sensors/d...PX5010.pdf

They claim a 5% maximum error. We're measuring pressures on the order of 10 cm H2O, and 5% of that is 0.5 cm H2O.

It might be suitable. Barely.

It would be more fun to salvage one from a CPAP machine!

[APAAW]

I wonder if that same Freescale component couldn't be going into some CPAPs. They might be selected for accuracy, or maybe just calibrated to adjust for consistent errors out of the component (assuming the error is consistent over time and a reasonable range of temperatures, etc.).

It sounds like you've got access to the lab equipment to settle this and some other questions. The results will be interesting. Thanks much!

[cowboy1970]

I won't mention my doctor's name because I noticed others aren't naming names either, but I am frustrated and very tempted. lol

I left a message with my doctor's office yesterday, explaining that I wanted a ResMed S9 AutoSet with H5i humidifier, washable tub, climateline, and puritan breeze mask. I told them the pressure settings I used for years before were MIN STARTING 9 - MAX 20. The machine kept it around 11 most of the night.

This morning they called back to tell me that this would be fine, except they will only set the air to 9, no adjusting. They said this is what the sleep study said would work for me. They also said that I can always come in as often as I like to have the air adjusting up or down if needed. (kaching kaching)

This makes no sense to me. Is my doctor just being stubborn or has no understanding of how the autoset works?

[retired_guy]

Sometimes they just think the more control they exercise on their patients the easier their life will be. That's pretty much true I suppose, but around here it's all about patient empowerment.

so......................... If my doc told me they were going to set my machine at 9 and just leave it at that, I'd say "thanks a bunch," go home and do what I do.

Using your experience as an example, I'd be setting my machine to a low of 8 or 9, and a high of about 14. I don't like leaving the machine full out because that too can sometimes cause goofy things to happen.