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

[Reznik]

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.

Thanks Walla Walla!

I haven't really looked into the operation of the Respironics machines because the documentation that they provide isn't nearly as detailed as the documentation from ResMed.  

As I noted in an earlier post, however, I think that "Flow Limitation" may be a term that does not have a consistent meaning.  

For example, Resmed defines flow limitation as "any event that limits the flow of air into your body, due to a blockage (or obstruction) in your upper airway."  

https://www.resmed.com/us/en/consumer/su...aries.html

And in their ASV documentation, they make clear that flow limitations are addressed by adjusting EPAP.

These two things suggest to me that Resmed thinks of "flow limitations" differently than Respironics - particularly if they respond by adjusting IPAP.  I'll have to look into this further.

Update:  Another possibility is that there are multiple types of flow limitations and that Respironics machines can distinguish between them and treat different types of flow limitations differently.  The graph you provided may be an example of the type that Respironics treats with increased IPAP.

Can you zoom in to the actual breathing wave-form on one of those flow limitations so that we can see what the wave-form actually looked like during the "flow limitation"??

[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.

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.

That's why it makes intuitive sense that C-Flex would shorten time of expiration - pressure rising before expiration finishes could prematurely terminate expiration and start inspiration.  Whether that matters, I don't know.

[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.

That's why it makes intuitive sense that C-Flex would shorten time of expiration - pressure rising before expiration finishes could prematurely terminate expiration and start inspiration.  Whether that matters, I don't know.

My personal experience was that I didn't notice any problems completing exhalation, but it definitely prompted immediate inspiration in a way that the ResMed machine did not.  Of course, I'm sample of one, so I don't give that much credence for anyone but me.

[Sleepster]

Correct me if I've got this wrong, but it sounds like you were titrated in CPAP at 13cm. 

Yes, I told you that several times.

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[...]

It worked just as well. Increasing the pressure to 16 cm was not necessary.

Did I miss anything?

So far you've missed the fact that when you turn on EPR it's not (often or even usually) necessary to raise the pressure to compensate.

[Reznik]

Correct me if I've got this wrong, but it sounds like you were titrated in CPAP at 13cm. 

Yes, I told you that several times.

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[...]

It worked just as well. Increasing the pressure to 16 cm was not necessary.

Did I miss anything?

So far you've missed the fact that when you turn on EPR it's not necessary to raise the pressure to compensate.

That's because your initial titration was wrong.  You didn't need 13cm of EPAP.  

You only needed 9cm of EPAP and 13cm of IPAP!  So, turning on EPR got you 10cm of EPAP and 13cm of IPAP, which was closer to what you needed.

Had your titration been correct, and had you needed 13cm of EPAP, turning on EPR would have give you less than you needed, and you would have had to adjust the machine's stated pressure up to 16cm in order to get the 13cm of EPAP that you needed.  But, again, you didn't because your initial CPAP titration resulted in an erroneous setting, as evidenced by the your re-titration to BiPap and your current settings.

[Sleepster]

So far you've missed the fact that when you turn on EPR it's not necessary to raise the pressure to compensate.

You didn't need 13cm of EPAP.  You only needed 9cm of EPAP and 13cm of IPAP!  So, turning on EPR got you 10cm of EPAP and 13cm of IPAP, which was closer to what you needed.

Regardless of the reason, it's still true that when I turned on EPR I didn't need to raise the pressure to compensate.

[Reznik]

So far you've missed the fact that when you turn on EPR it's not necessary to raise the pressure to compensate.

You didn't need 13cm of EPAP.  You only needed 9cm of EPAP and 13cm of IPAP!  So, turning on EPR got you 10cm of EPAP and 13cm of IPAP, which was closer to what you needed.

Regardless of the reason, it's still true that when I turned on EPR I didn't need to raise the pressure to compensate.

Well, of course.  If your titration is wrong, then any statement that relates to your titration is going to yield an incorrect result.  It's a "garbage in, garbage out" situation.

But your situation actually did quite a bit to prove my underlying premise, i.e. that enabling EPR turns your CPAP into a BiPap with the displayed pressure as IPAP and the EPAP set at IPAP minus EPR.

So, thank you for your contribution. 

[Sleepster]

And if all CPAP titrations are done the same way?

[Reznik]

And if all CPAP titrations are done the same way?

Then everybody gets candy for Christmas?

[Walla Walla]

I get where Sleepster is coming from. When titrations are done the pressure is set for all events not just obstructive events. By setting the pressure to also include Hyponeas it allows room for the EPR to be set without resulting in OA's. It takes less pressure to remove OA's than it does Hyponeas. That's why a DreamStation Bipap can use a variable pressure support. The EPAP can stay at a lower level to take care of OA's while the IPAP can increase to take care of Hyponeas.