Isn't Resmed's Expiratory Pressure Relief really Inspiratory Pressure Support??

[Sleepster]

Your profile indicates that you use an AirCurve 10 VAUTO with a maximum IPAP of 13.6 and a minimum EPAP of 5.2, and with a pressure support of 4.4.  That tells me that you have not been titrated to a CPAP of 13 cm.

Wow!

What does my telling you that I was titrated at 13 cm tell you?

[...]if you actually were titrated to CPAP using an AirSense 10 Autoset at 13 with EPR Off, and then found that setting EPR to 3 was just as effective, I'd ask whether you've ever tried turning EPR off and setting your pressure at 10. 

Yes.

I'd expect that would be just as effective at controlling obstructive apneas as setting the machine at 13 with EPR set to 3.

And your expectations would be wrong.

You mentioned in another post that you're being scientific. When your expectations don't match what's observed the scientific response is to alter your expectations.

[yrnkrn]

A good sleep medicine book helps appreciate the complexity of the airway and the dynamics contributing to its collapse.

I have found "Principles and Practice of Sleep Medicine" by Meir H. Kryger, clear and thorough reading about the subject, chapters:
"Anatomy and Physiology of Upper Airway Obstruction" & "Snoring and Pathologic Upper Airway Resistance Syndromes"

Most of these pages are available to read in the Google book store. Commercial link removed.

The section "Phase of the Respiratory Cycle: Inspiratory Versus Expiratory Narrowing" shows how airway obstruction may develop over the course of several breaths, hence affected by the whole pressure waveform, IPAP as well as EPAP. Not all obstructions are the same.

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[TBMx]

I am unsure how the titration studies are really made. I have however some doubts that there is actually someone doing the changes by hand. More likely they let some APAP do the job and decide from there. (at least that was my impression in my titration-night)

ResMed's AutoSet-Algorithm reacts to flowlimitations. If you look on the last benchmark study ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4792477/ ) it looks like there is more than enough room for EPR before the EPAP even comes close to ranges where you can suspect (real) obstructions. So, if any AirSense is not constantly on the upper pressure range, it is highly unlikely that EPR (at any level) will result in more OAs.
Or - as you have stated it - less pressure would do the very same job just fine. (regarding obstructional events) ... there is the soft-response and the for-her-mode if you want that.

[Reznik]

Your profile indicates that you use an AirCurve 10 VAUTO with a maximum IPAP of 13.6 and a minimum EPAP of 5.2, and with a pressure support of 4.4.  That tells me that you have not been titrated to a CPAP of 13 cm.

Wow!

What does my telling you that I was titrated at 13 cm tell you?

It tells me that you're giving information that is at odds with what's in your profile, without explaining the apparent contradiction.  You might have been giving me a hypothetical example.  You might just be making it up in order to support your position.  Or, there might be an explanation for the apparent contradiction that you're not giving me.  

For example, you might have gotten an initial titration at 13 cm CPAP, failed on CPAP, and then converted to BiPAP.  If you failed on CPAP and had to convert to BiPap, then the outcome of the titration may have been wrong.

I'm sure that there are countless other things that it could mean.  Without knowing you, and getting more information, I can't say for sure.

[...]if you actually were titrated to CPAP using an AirSense 10 Autoset at 13 with EPR Off, and then found that setting EPR to 3 was just as effective, I'd ask whether you've ever tried turning EPR off and setting your pressure at 10. 

Yes.

I'd expect that would be just as effective at controlling obstructive apneas as setting the machine at 13 with EPR set to 3.

And your expectations would be wrong.

You mentioned in another post that you're being scientific. When your expectations don't match what's observed the scientific response is to alter your expectations.

I never said that I was being scientific.  I said that I was repeating information provided by people who were being scientific.

Having said that, in science, we never alter our expectations based upon the claimed experience of a single person.  Rather, we require either consensus (everyone agrees) or trials that involve a group of people larger than one person making a claim on the internet before we alter our expectations.

With respect to altering expectations, you've given me limited information, and so I've told you what my expectations would be for each of the possible variations of the information that you left out.

As it is, you have still given me no reason to doubt that you're now using an AirCurve 10 VAUTO configured as indicated in your profile.  I'm still not surprised by your statements about the Autoset machine working better at 13.0 cm with EPR 3 than at 10.0 cm with EPR 0 for the reasons that I stated in my last message, i.e., both the Aircurve 10 VAUTO programmed as indicated in your profile (when near its maximum) and the AirSense 10 Autoset programmed at 13.0 cm with EPR 3 will both produce very similar mask pressures and identical pressure wave forms.  At 10.0cm with EPR 0, you'd have no pressure support, and it would seem that you need it.

Since the limited information you've given me matches my expectations, there really isn't a reason to alter them.  If you have additional information that requires me to alter my expectations, I'd be delighted to read it!

[Reznik]

The section "Phase of the Respiratory Cycle: Inspiratory Versus Expiratory Narrowing" shows how airway obstruction may develop over the course of several breaths, hence affected by the whole pressure waveform, IPAP as well as EPAP. Not all obstructions are the same.

Since IPAP is always higher than EPAP, it seems that the sleep technologists and doctors view the EPAP portion of the IPAP as what holds open the airway during inspiration, and the Pressure Support as what forces the air intake.

In other words, if you're at 5 EPAP and 8 IPAP, the doctors would say that the 5.0 units of pressure that is present during expiration and inspiration is what is keeping your airway open all the time, and the extra 3.0 units of Pressure Support (the difference between EPAP and IPAP) delivered only when you inspire is forcing you to take a complete breath (rather than a shorter breath or hypopnea).

Here's a web-site that explains it in more detail:

https://thenursepath.blog/2017/02/08/cpa...e-is-best/

IPAP "will provide an increased support as the patient breathes in.  Further decreasing WOB [work of breathing] (and therefore resp muscle fatigue and myocardial oxygen demand).

This increased pressure also encourages the patient to take bigger breaths (or Tidal Volumes) which helps remove any excess CO2 from the bloodstream."

I've read a ton of material that says the same thing.  This is the first one that Google pulled up for me today.  

[Sleepster]

It tells me that you're giving information that is at odds with what's in your profile, without explaining the apparent contradiction.

After a few weeks of straight CPAP I was switched to BiPAP and then later I switched myself to what I have now.

Along the way I did everything that I've said I did in this thread, and I've repeated much of it to you several times. Others are trying to tell you the same thing I'm telling you.

[Shin Ryoku]

I have a separate observation which I think may be relevant to this thread.

When I use my Respironics Dreamstation with C-Flex, my I:E ratio is greater than 1, whereas when I use my Resmed Airsense 10 Autoset with EPR, my I:E ratio is less than 1. It makes intuitive sense to me that C-Flex would increase the I:E relative to what EPR would do.

Which leads to another question: what is an optimal I:E ratio for someone who does not have restrictive or obstructive lung disease aside from OSA? Certainly the lower I:E is more "normal", but does it matter?

When I use my Resmed AirCurve 10 Vauto with PS 5, my I:E ratio goes even lower than with the Autoset, closer to 1:2. This may be due to the Ti Max rather than the PS setting but not sure.

[Walla Walla]

Reznik,
             I posted this for you. Before you said you didn't know how the DreamStation reacted to different events.
On this chart you can see that the EPAP responds to OA's and the IPAP responds to Flow limitations and Hyponea's.
PS is set from 3 to 4. You can see where the IPAP raises in response to flow limitations and increases the PS to 4. You can also see where the EPAP raises in response to OA's and reduces the PS to 3. Figured since you want to write about the machines you'd like a first hand look.

[Reznik]

It tells me that you're giving information that is at odds with what's in your profile, without explaining the apparent contradiction.

After a few weeks of straight CPAP I was switched to BiPAP and then later I switched myself to what I have now.

Along the way I did everything that I've said I did in this thread, and I've repeated much of it to you several times. Others are trying to tell you the same thing I'm telling you.

Thanks for supplementing that information.  

It sounds as if my assumptions were correct, and my statements explain your situation.  

Correct me if I've got this wrong, but it sounds like you were titrated in CPAP at 13cm.  You found that switching on EPR at 3 worked better, which according to my beliefs changed your machine to a Bi-Level with IPAP 13 and EPAP at 10 (Pressure Support of 3), and that worked better but still not as well as you'd like, and now you're at a true bi-level with an even higher Pressure Support of 4.4, with your upper limit IPAP still at 13 and your upper limit EPAP now about 9.

Did I miss anything?

[Reznik]

I have a separate observation which I think may be relevant to this thread.

When I use my Respironics Dreamstation with C-Flex, my I:E ratio is greater than 1, whereas when I use my Resmed Airsense 10 Autoset with EPR, my I:E ratio is less than 1.  It makes intuitive sense to me that C-Flex would increase the I:E relative to what EPR would do.

Which leads to another question: what is an optimal I:E ratio for someone who does not have restrictive or obstructive lung disease aside from OSA?  Certainly the lower I:E is more "normal", but does it matter?

When I use my Resmed AirCurve 10 Vauto with PS 5, my I:E ratio goes even lower than with the Autoset, closer to 1:2.  This may be due to the Ti Max rather than the PS setting but not sure.

Not sure if this matters, but C-Flex is totally different from ResMed's EPR.  C-Flex truly is expiratory pressure relief, because the machine returns to IPAP as you are exhaling and before you start inspiring.