pressure not changing

[jimbud]

Post by biomed » Wed Sep 18, 2019 9:52 am
It almost worked.

by biomed » Wed Sep 18, 2019 10:52 am
It "almost" worked.


I'm just dumb.

O.K.

[biomed]

Those of you who question why your OSCAR pressure reading isn't varying - the RED trace - what you may be seeing isn't the actual sensed pressure - it's the programmed pressure.

You're neither crazy nor stupid. Put your mind to rest.

If you have an APAP, set to Ramp, the programmed pressure will ramp from its initial to its final value, then stays there, without even the slightest variation.

I don't know yet, what a BIPAP or other device does with its programmed pressures.

One way to tell - turn the machine on, with a hose, but without Ramp. Plug the end of the hose with your finger or palm, then remove and replace it several times, for a few seconds. If the readout never changes, what you're seeing isn't the actual pressure - it's the programmed pressure.

With good advice from this forum, I've been told my DreamStation doesn't output actual pressure.

I'm just dumb enough to find out why.

After installing Sleepyhead, I see it does the same thing as Oscar. That part of Sleepyhead wasn't changed when OSCAR supplanted it.

For my DreamStation, the RED trace shows what looks like the programmed or desired pressure, not the actual pressure. That doesn't mean it doesn't exit. The machine absolutely needs it to function. It simply means the DreamStation doesn't send it to the sim card or the software is presenting the programmed value data. I'll ask my provider if his or her professional program shows it.

I'm not sure yet, whether I want to trade machines and discover something else isn't being presented - even worse - something doesn't work.

[palerider]

. Yes, I'm a beginner to an actual CPAP, but crazy (or stupid?) enough to DIY my own manometer. Three years ago, when there was a shortage of CPAP blower motors on ebay, I actually built my own, with a Dustbuster hand vacuum cleaner motor. It almost worked, but it was pretty noisy.

Ron

I think this is where I throw in a

[palerider]

I'll eventually find out why the Respironics sensor readout isn't available, at least in OSCAR.

It's not available because Respironics chose not to record the data. If it'd been recorded, it'd be displayed in sleepyhead, and now Oscar.

. It "almost" worked.

uh....

Depending on how forcefully I exhale, the pressure does drop to 7 and actually undershoots if I puff.

Your home made toy isn't accurate enough to measure this accurately, thanks to the mass you've added to the equation.

So, the actual setup behaves as the Philips control loop people and any other servo designer might expect. Given enough time to settle, the loop does, in fact, go from 10 to 7 and back.

Your allegation is inconsistent with Philips Respironics own documentation on the subject.

[palerider]

Those of you who question why your OSCAR pressure reading isn't varying - the RED trace - what you may be seeing isn't the actual sensed pressure - it's the programmed pressure.

That would be you.

You're neither crazy nor stupid. Put your mind to rest.

Data insufficient to determine.

I'm just dumb enough ...

noooooooo comment.

[palerider]

I've been on breath-assist therapy for 2 months.

Breath-assist therapy??????

Some people have trouble with words, don't make fun of their disabilities.

[palerider]

it to the sim card

One is amazed that someone who alleges to be so technical as yourself, doesn't know the difference in a SIM card and a SD card.

[biomed]

it to the sim card

One is amazed that someone who alleges to be so technical as yourself, doesn't know the difference in a SIM card and a SD card.

I'll eventually find out why the Respironics sensor readout isn't available, at least in OSCAR.

It's not available because Respironics chose not to record the data. If it'd been recorded, it'd be displayed in sleepyhead, and now Oscar.

. It "almost" worked.

uh....

Depending on how forcefully I exhale, the pressure does drop to 7 and actually undershoots if I puff.

Your home made toy isn't accurate enough to measure this accurately, thanks to the mass you've added to the equation.

So, the actual setup behaves as the Philips control loop people and any other servo designer might expect. Given enough time to settle, the loop does, in fact, go from 10 to 7 and back.

Your allegation is inconsistent with Philips Respironics own documentation on the subject.

Dear palerider,

I'm trying to be respectful, not a smart**s. All those plug-in thingies look the same to me. The difference is - I'm a hardware "puke" who can tell you exactly what's in them. I retired from a major semiconductor company that made them. Somewhere in the late 60s, when I reminded myself I loved analog hardware more than software or digital design, I quit writing code.

If you'd provide a link where Philips engineers, not sales types, document servo behavior to be significantly different from what I've casually observed, I'd be grateful.

If you're talking about the mass of the water in the manometer, it certainly adds a delay, but if that delay is less than the spool up-down time of the CPAP blower, and you insure the manometer response is critically damped, I'd expect it to track pressure well enough to get a decent idea of what happens. I'm sure it has little effect on the main pressure/flow. I have plenty of instrumentation to back up everything if desired. Then we can both tell if I'm full of it or not.

Two of many ways to get an idea of what's happening, 1) notice how back pressure feels when you exhale, 2) listen closely to the blower - its displacement and pressure are roughly proportional to speed - maybe not linearly, but close enough to tell what the loop is doing.

I'm not ready to argue or even discuss CPAP medical terminology. I'm too new to the process.

The reason the vacuum cleaner motor "almost" worked - unlike most small blowers, it has a large pressure near stall. That's why it sucks well as a vacuum
cleaner. When there was a sparsity of reasonably-priced used CPAP blowers online, I decided to try it. A 16 Volt vacuum cleaner motor is still pretty noisy at 4 Volts. I didn't get around to closing the loop with one of my pressure sensors, but everything is still in the garage.................

[palerider]

it to the sim card

One is amazed that someone who alleges to be so technical as yourself, doesn't know the difference in a SIM card and a SD card.

I'm trying to be respectful, not a smart**s. All those plug-in thingies look the same to me. The difference is - I'm a hardware "puke" who can tell you exactly what's in them.

Apparently not, if you don't know the difference in a SD card and a sim card.... given that they're completely and totally different in shape purpose and content.

I retired from a major semiconductor company that made them.

Not much rubbed off, eh?

Your allegation is inconsistent with Philips Respironics own documentation on the subject.

If you'd provide a link where Philips engineers, not sales types, document servo behavior to be significantly different from what I've casually observed, I'd be grateful.

You'll notice the pressure drop shown at settings of 1, 2, and 3. and notice, that this is a *Philips Respironics* chart.

[ragtopcircus]

Btw, the EPAP waveform reported by the current released version of Oscar is incorrect for PR Dreamstation CPAP/APAP. It is reportedly the rolling average pressure over a 2 minute pressure. It is not EPAP. I don’t know whether that is the average commanded pressure or measured. The IPAP waveform appears to be, as already discussed, the commanded therapy pressure, not the actual pressure.

[ragtopcircus]

You'll notice the pressure drop shown at settings of 1, 2, and 3. and notice, that this is a *Philips Respironics* chart.

Those are very interesting charts ... they explain a lot to me. Thanks for posting them.

[palerider]

Btw, the EPAP waveform reported by the current released version of Oscar is incorrect for PR Dreamstation CPAP/APAP. It is reportedly the rolling average pressure over a 2 minute pressure. It is not EPAP. I don’t know whether that is the average commanded pressure or measured. The IPAP waveform appears to be, as already discussed, the commanded therapy pressure, not the actual pressure.

respironics data is lacking. The machine provides commanded IPAP, and approximate EPAP derived from the variability of *flex. Since flex varies with the breathing effort, there is no commanded EPAP.

Regardless, that *is* EPAP.

Resmed provides actual desired and measured pressures, separately.

[biomed]

I've been on breath-assist therapy for 2 months.

Breath-assist therapy??????

Some people have trouble with words, don't make fun of their disabilities.

"Breath assist" was the first description that came to mind. I believe if you Wikipedia under "CPAP", it, or a similar term, was used by the author, who appears to have the same verbal handicap.

[palerider]

I've been on breath-assist therapy for 2 months.

Breath-assist therapy??????

Some people have trouble with words, don't make fun of their disabilities.

"Breath assist" was the first description that came to mind. I believe if you Wikipedia under "CPAP", it, or a similar term, was used by the author, who appears to have the same verbal handicap.

Nope. Unless by "similar" you mean 'completely different'.

Also, the wikipedia article for cpap is utter crap.

[biomed]

I've been on breath-assist therapy for 2 months.

Breath-assist therapy??????

Some people have trouble with words, don't make fun of their disabilities.

"Breath assist" was the first description that came to mind. I believe if you Wikipedia under "CPAP", it, or a similar term, was used by the author, who appears to have the same verbal handicap.

Nope. Unless by "similar" you mean 'completely different'.

Also, the wikipedia article for cpap is utter crap.

Does anything please you?