pressure not changing

[charlieleeas]

I am curious if anyone else has ever had an experience like this..... My machine is set to move between 6 and 20 as needed. When I turn it on and lay there it stays pretty constant at 6.4. I just spoke with the folks monitoring the readout of the machine. I had the mask on for one hour, I experienced three incidents (holding my breath for ten seconds or more) and the pressure on the machine never increased beyond a 6.9.

Is this odd? I would think if I had an incident the pressure would have increased substantially? Regardless of your mask or machine you use or any other person specific details, is this odd for the pressure set by the doctor not to move substantially during an incident?

[chunkyfrog]

Funny thing about apnea--it usually waits until you are asleep, sometimes deeply asleep.
I suggest you download Sleepyhead, and use your data to see what is happening.
See Pugsy's sleepyhead thread near the top of the sticky threads.

[Julie]

While the machine doesn't 'know' if you're awake or not, it can tell that your breathing pattern is not what it's supposed to respond to, let alone for only an hour. You can't fake asleep breathing and you need to sleep for at least 3-4 hrs to get a valid result, so first try the real thing and if you still have trouble (no cheating ) then ask the dealer about it.

[LSAT]

I am curious if anyone else has ever had an experience like this..... My machine is set to move between 6 and 20 as needed. When I turn it on and lay there it stays pretty constant at 6.4. I just spoke with the folks monitoring the readout of the machine. I had the mask on for one hour, I experienced three incidents (holding my breath for ten seconds or more) and the pressure on the machine never increased beyond a 6.9.

Is this odd? I would think if I had an incident the pressure would have increased substantially? Regardless of your mask or machine you use or any other person specific details, is this odd for the pressure set by the doctor not to move substantially during an incident?

It has no reason to go higher unless it senses an apnea...you won't have real apneas when you are awake. If you hold your breath, there is not necessarily a closing at your throat as there is with a real apnea. Your machine may show a CA (Clear airway apnea)where the machine will not increase pressure.

[Guest]

I am curious if anyone else has ever had an experience like this..... My machine is set to move between 6 and 20 as needed. When I turn it on and lay there it stays pretty constant at 6.4. I just spoke with the folks monitoring the readout of the machine. I had the mask on for one hour, I experienced three incidents (holding my breath for ten seconds or more) and the pressure on the machine never increased beyond a 6.9.

Is this odd? I would think if I had an incident the pressure would have increased substantially? Regardless of your mask or machine you use or any other person specific details, is this odd for the pressure set by the doctor not to move substantially during an incident?

What "machine" are you using?

No, it's not "odd". It's working as designed. Most APAPs set in ranges of pressures only increase pressures on Flow Limitations and/or Snores. They won't increase pressure on Apneas (depending on the particular machine).
Get Sleepyhead software so you can see and study your own data.
These machines have algorithms which respond to "air flow" and do what they do for specific reasons.

[ChicagoGranny]

I am curious

You sound like the type of person who will enjoy looking at exactly what is happening, breath by breath --->

https://sleep.tnet.com/resources/sleepyhead
https://sleep.tnet.com/resources/sleepyhead/shorganize
https://sleep.tnet.com/reference/tips/imgur

is this odd for the pressure set by the doctor

Because the doctor always sets the right pressure.

[biomed]

Dear chicagogranny,

I've been on breath-assist therapy for 2 months. 1 month ago, my Philips DreamStation APAP pressure was raised from 8 to 10 cm by my sleep therapist. I've set the C-flex pressure relief to 3 cm.

I've spliced my DIY U-tube differential manometer into the machine end of the hose and read exactly 10 cm when I hold my breath. When inhaling, the manometer indicates a bouncy 10 cm and exhaling, a bouncy 7 cm, exactly as they should.

I understand C-flex varies its dynamic response to slow versus fast "puffy" exhales. Exhale pressure ramp and undershoot depend on the "puff" or exhale time-rate-of-volume change.

I've just installed OSCAR and, for the moment, I'm simply observing expanded views of flow rate and pressure over "uneventful" 1 and 2 minute segments. The typical breath-by-breath flow regularly cycles from +15 to -25 Liters/minute. Also appears fine.

But the RED pressure readout is rock steady. Never fluctuates, so I'm assuming it's the "demand" or programmed pressure readout, not the actual sensor pressure readout. The GRN or EPAP pressure readout fluctuates slightly, but doesn't reflect any discernible pattern or cycle. Somewhere, a readout should indicate cyclical pressure variation from 10 to 7 cm.

Would you or any other knowledgeable person reading this reply, please tell me if and how I can find an OSCAR readout of the actual pressure. I'll try Sleepyhead and post in other forums (as a very old Latin student, I should say "fora").

My loving bride for 58 years rags on me because I tend to scan instructions and always miss the important stuff.

That's why God invented GPS - to keep dumb male drivers from constantly refusing to ask where they are.

Thanks for your links on Sleepyhead and other breath-by-breath aids.

Ron

[ChicagoGranny]

Somewhere, a readout should indicate cyclical pressure variation from 10 to 7 cm.

How would this help any patient improve his therapy?

[palerider]

Dear chicagogranny,

I've been on breath-assist therapy for 2 months. 1 month ago, my Philips DreamStation APAP pressure was raised from 8 to 10 cm by my sleep therapist. I've set the C-flex pressure relief to 3 cm.

That's not how *flex works, it varies, but never gets to 3cm drop.

and exhaling, a bouncy 7 cm, exactly as they should.

Again, no, *flex doesn't drop pressure that much.

. Somewhere, a readout should indicate cyclical pressure variation from 10 to 7 cm.

No

Would you or any other knowledgeable person reading this reply, please tell me if and how I can find an OSCAR readout of the actual pressure.

Get a Resmed, they report measured pressure, respironics don't.

[LSAT]

Dear chicagogranny,

I've been on breath-assist therapy for 2 months. 1 month ago, my Philips DreamStation APAP pressure was raised from 8 to 10 cm by my sleep therapist. I've set the C-flex pressure relief to 3 cm.

I've spliced my DIY U-tube differential manometer into the machine end of the hose and read exactly 10 cm when I hold my breath. When inhaling, the manometer indicates a bouncy 10 cm and exhaling, a bouncy 7 cm, exactly as they should.

I understand C-flex varies its dynamic response to slow versus fast "puffy" exhales. Exhale pressure ramp and undershoot depend on the "puff" or exhale time-rate-of-volume change.

I've just installed OSCAR and, for the moment, I'm simply observing expanded views of flow rate and pressure over "uneventful" 1 and 2 minute segments. The typical breath-by-breath flow regularly cycles from +15 to -25 Liters/minute. Also appears fine.

But the RED pressure readout is rock steady. Never fluctuates, so I'm assuming it's the "demand" or programmed pressure readout, not the actual sensor pressure readout. The GRN or EPAP pressure readout fluctuates slightly, but doesn't reflect any discernible pattern or cycle. Somewhere, a readout should indicate cyclical pressure variation from 10 to 7 cm.

Would you or any other knowledgeable person reading this reply, please tell me if and how I can find an OSCAR readout of the actual pressure. I'll try Sleepyhead and post in other forums (as a very old Latin student, I should say "fora").

My loving bride for 58 years rags on me because I tend to scan instructions and always miss the important stuff.

That's why God invented GPS - to keep dumb male drivers from constantly refusing to ask where they are.

Thanks for your links on Sleepyhead and other breath-by-breath aids.

Ron

I assure you...there are no other forums with as much knowledge as you will get here.

[palerider]

other forums (as a very old Latin student, I should say "fora").

According to no less than the Oxford English Dictionary:

The plural of forum is usually spelled forums; the plural fora (as in the original Latin) is chiefly used when talking about a public square in an ancient Roman city.

[biomed]

Somewhere, a readout should indicate cyclical pressure variation from 10 to 7 cm.

How would this help any patient improve his therapy?

Dear Chicago Granny,

Thanks for the feedback.

At this point, I don't think it would. But I'm also a biomedical electronics engineer (plz see my profile). 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

[biomed]

Dear chicagogranny,

I've been on breath-assist therapy for 2 months. 1 month ago, my Philips DreamStation APAP pressure was raised from 8 to 10 cm by my sleep therapist. I've set the C-flex pressure relief to 3 cm.

That's not how *flex works, it varies, but never gets to 3cm drop.

and exhaling, a bouncy 7 cm, exactly as they should.

Again, no, *flex doesn't drop pressure that much.

. Somewhere, a readout should indicate cyclical pressure variation from 10 to 7 cm.

No

Would you or any other knowledgeable person reading this reply, please tell me if and how I can find an OSCAR readout of the actual pressure.

Get a Resmed, they report measured pressure, respironics don't.

Dear Palerider,

Please understand - I mean no offense - in the short time I've been with this group, I agree - there are a number of very sharp contributors.

The reason I'm flagellating myself with this techie stuff is, like you, I'm a techie and I'm new to the process. I'll eventually find out why the Respironics sensor readout isn't available, at least in OSCAR. I have several MEMS electronic differential pressure sensors to back up my DIY manometer. I was experimenting with pressure feedback to linearize the subwoofer I'd built for my SUV. It "almost" worked.

CPAP - I decided this time to go the Medicare route, do my 3rd sleep study and actually let the lab send my prescription to an equipment provider. I've been using the DreamStation for 2 months of a 13? month trial. I could have just simply bought one, but without a trial, I would have certainly screwed up.

The therapy seems to be working fine, although I haven't tried my recording oximeter since the lab upped my inhale pressure from 8 to 10 cm.

BTW - when I'm awake and purposely exercise the machine, the manometer is showing a dynamic pressure drop. Steady-state Inhale or breath-holding are both 10, as they should be.

Depending on how forcefully I exhale, the pressure does drop to 7 and actually undershoots if I puff. If I quickly stop exhaling and hold my breath, the pressure ramps about 90% of the way towards 10 cm Inhale, then slows slightly, and creeps the rest of the way.

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. Under dynamic conditions, it behaves differently, depending on what mad scientists call "time-rate-of-pressure change" i.e.
the first and higher pressure derivatives or "puff".

What I'm trying to see it what happens when I actually sleep.

[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.

[Dog Slobber]

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

Breath-assist therapy??????