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

[mhehe]

There seems to be a misunderstanding, that I also shared, if you read a recent post. It is common in groups to have a shared falsehood. I too took what was said for granted, that you raise the ipap when you add epr and passed it on.

I now think I was wrong. we aren't working from the epap end and adding PS to increase ipap. you already have the ipap right. So adding epr just gives you, what could be called an epap setting. It shouldn't affect the treatment pressure, be it EPR 1,2 or 3

I'm afraid I don't quite understand what you're saying here.  

EPAP is the pressure that the machine gives during expiration, during any transition from expiration to inspiration (or the other way around), and during any apnea.  In CPAP therapy, EPAP is the same as IPAP.  In Bi-Level Therapy, EPAP is always LOWER than IPAP.

IPAP is the pressure that the machine gives during inspiration.  In machines that are spontaneous, the IPAP is only delivered after the patient initiates inhalation and stops as soon as the patient stops inhalation.  In machines that are timed (or timed backup), the IPAP will be delivered at the programmed time interval to force inspiration even when it has not happened.  In CPAP therapy, IPAP is the same as EPAP.  In Bi-Level Therapy, IPAP is always HIGHER than EPAP.

Pressure Support is IPAP minus EPAP.

When we speak of "increasing Pressure Support," we are increasing the difference between IPAP and EPAP.  So, if IPAP = 8 and EPAP = 5, you have a Pressure Support of 3.  If you increase IPAP to 9, pressure support increases to 4.  But, if you increase IPAP to 9 and EPAP to 6, then Pressure Support remains at 3.

When a ResMed AirSense 10 model is in AutoSet mode, enabling Expiratory Pressure Relief converts the machine to a spontaneous (non-timed) BiPap Mode, where the displayed pressure on the screen is the IPAP, the EPR level (1, 2, or 3) is the amount of Pressure Support, and the EPAP is the displayed pressure minus the EPR level.

So, if a ResMed Airsense 10 is set for 10.0 without EPR enabled, then the patient is receiving EPAP at 10, IPAP at 10, and Pressure Support is 0.  If the patient enables EPR at 3, then his EPAP lowers to 7 (3 below the machine's stated pressure), his IPAP remains at 10 (the machine's stated pressure), and his Pressure Support increases to 3 (IPAP of 10 minus EPAP of 7 = 3).  

Far from getting expiration relief, the patient is actually getting LESS than his prescribed EPAP pressure (7 instead of 10) and a healthy dose of pressure support (3.0) that he may not need and which may actually cause him problems.  The patient may even complain that the machine feels as if it is inflating his lungs when he breathes in.  That's why I say EPR is really Inspiratory Pressure Support, and not Expiratory Pressure Relief.

On the other hand, if a patient is titrated to BiPap therapy at EPAP of 8 and IPAP of 10 and given a $1,700 AirCurve 10 S or VAUTO, that patient could get the same therapy with a cheaper $800 AirSense 10 CPAP or Autoset or an AirMini set to 10 with EPR set a 2.0.  A machine so configured would deliver EPAP 8.0 and IPAP 10.0, just like the more expensive AirCurve 10 when set to those settings.

I'll post in another message (in reponse to Sleepster's question) why EPAP is what matters when it comes to preventing obstructions.

I hope this clarifies things.

I think you are confusing matters even more. For example in the BiPAP machine that I am using, Res Med AirCurve 10 VPAP auto, IPAP and PS are set. Then EPAP is IPAP - PS. PS is fixed but can be programmed to a lower or higher value. In the titration at home or in the clinic it is normally set at 4.0 cm. to start with. In my case the sleep technician has set the machine in Auto mode with EPAP min of 7.0, IPAP max of 25 and PS of 4.0. The machine starts of with EPAP = 7.0 and IPAP of 11.0. I want my night to start of with an EPAP of 8.0 and IPAP of 12 to handle my OSA and HA.

[Reznik]

I think you are confusing matters even more. For example in the BiPAP machine that I am using, Res Med AirCurve 10 VPAP auto, IPAP and PS are set. Then EPAP is IPAP - PS. PS is fixed but can be programmed to a lower or higher value. In the titration at home or in the clinic it is normally set at 4.0 cm. to start with. In my case the sleep technician has set the machine in Auto mode with EPAP min of 7.0, IPAP max of 25 and PS of 4.0. The machine starts of with EPAP = 7.0 and IPAP of 11.0. I want my night to start of with an EPAP of 8.0 and IPAP of 12 to handle my OSA and HA.

Hi Mhehe,

Again, thanks for responding.  

I'm sorry if I caused any confusion.  I think that you're right that the AirCurve 10 VAUTO, even in VAUTO mode, does not adjust the Pressure Support.  The clinical manual indicates that Pressure Support is fixed.  The machine then adjusts the EPAP (and only in order to maintain the fixed pressure support, the IPAP) to respond to inspiratory flow limitations, obstructive apneas, and snore.  It looks to be identical to what the AirSense 10 Autoset does, except that the VAUTO allows for Pressure Support that is greater than 3.0, or in increments that are not whole numbers (i.e. 2.2 or 1.6), while the AirSense 10 Autoset can only get Pressure Support at 1, 2, or 3, via the EPR settings that I've been talking about.

If a doctor wants to prescribe variable pressure support, he'd prescribe the AirCurve 10 ASV (or something similar).  The ASV model adjusts pressure support on a real-time basis in the manner that I quoted from the Clinician's manual (in response to Sleepster's question) in order to address periodic breathing and central apneas, and, in Auto ASV Mode, also adjusts EPAP to respond to inspiratory flow limitations, obstructive apneas, and snore.

[holden4th]

My data and graphs tell me a different story. I've got IPAP set to a min of 13, EPAP to a min of 10.5 and a PS range of 2.5 to 5.0 which is something you can do with a Respironics BiPAP but not a resmed BiLevel. On these graphs I note that:

All my spikes are on the IPAP which says to me that the machine is trying to treat my events by raising the IP not the EP. I had 3 Hs, 4 CAs and 4 RERAs. The EPAP level stayed as a straight line all night.

[yrnkrn]

My data and graphs tell me a different story. I've got IPAP set to a min of 13, EPAP to a min of 10.5 and a PS range of 2.5 to 5.0 which is something you can do with a Respironics BiPAP but not a resmed BiLevel. On these graphs I note that:

Respironics and Resmed differ in bi-level treatment. Respironics adjust IPAP and EPAP independently while Resmed moves them together, keeping PS fixed.
Given both are world leaders in CPAP treatment, I guess both have their good reasons for going either way, which may just show there is no one "right" answer.

[Walla Walla]

In both the DreamStation and VAUTO EPAP responds to OA's. IPAP responds to H's, snoring and flow limitations.

[Reznik]

My data and graphs tell me a different story. I've got IPAP set to a min of 13, EPAP to a min of 10.5 and a PS range of 2.5 to 5.0 which is something you can do with a Respironics BiPAP but not a resmed BiLevel. On these graphs I note that:

All my spikes are on the IPAP  which says to me that the machine is trying to treat my events by raising the IP not the EP. I had 3 Hs, 4 CAs and 4 RERAs. The EPAP level stayed as a straight line all night.

That's not a different story.  Your machine is doing exactly what it should do based upon what I said earlier.  EPAP addresses obstructive apneas and flow limitations, and IPAP addresses hypopnea and central apneas.

BTW- it appears that you have a Resporonics Auto Bi-Level.  That machine is different than the ResMed models.

[Reznik]

My data and graphs tell me a different story. I've got IPAP set to a min of 13, EPAP to a min of 10.5 and a PS range of 2.5 to 5.0 which is something you can do with a Respironics BiPAP but not a resmed BiLevel. On these graphs I note that:

Respironics and Resmed differ in bi-level treatment. Respironics adjust IPAP and EPAP independently while Resmed moves them together, keeping PS fixed.
Given both are world leaders in CPAP treatment, I guess both have their good reasons for going either way, which may just show there is no one "right" answer.

Actually, the difference between how the two machines operate demonstrate that Resmed and Respironics do agree on how to address central apneas. 

The Respironics Bi-Pap Auto machine is marketed for the treatment of central apneas.  According to holden4th's post, it adjusts IPAP independently (i.e., Pressure Support) to address hypopnea and central apneas, which is exactly what ResMed's ASV manual says should be done for central apneas.

Resmed, on the other hand, doesn't adjust pressure support in their S, VAUTO, and ST machines, and therefore does not recommend them for the treatment of central apneas.  Instead, Resmed's titration guide recommends that patients with central apneas go straight to the ASV machine, which it claims adjusts Pressure Support to address centrals.

Based upon what the machines actually do and their marketing, it appears that both Resmed and Respironics agree on how to treat centrals.  Resmed just doesn't make that therapy available in their cheaper machines, while Respironics does.

[Walla Walla]

IPAP increases for flow limitations.

[Reznik]

In both the DreamStation and VAUTO  EPAP responds to OA's.  IPAP responds to H's, snoring and flow limitations.

You are definitely mistaken with respect to the VAUTO.  EPAP and IPAP in the VAUTO are fixed.  When one is changed, the other is changed as well so that pressure support is kept constant.

However, we know from the ASV manual that Resmed believes that it is EPAP that addresses OA, inspiratory flow limitations, and snore.  We also know from the ASV manual that Resmed believe that IPAP is what addresses central apneas and hypopneas.

It's been a while since I read the Dreamstation BiPap Auto clinical guide, but holden4th's posts seem to indicate that it adjusts IPAP to treat hypopnea and central apneas, which is what Resmed says it does in its ASV models as well.

[Walla Walla]

I own the VAUTO also. The IPAP responds to the flow limitations the EPAP goes up with the IPAP due to the PS. The EPAP is not responding to the flow limitations it's being drag up by the IPAP. Now when the EPAP responds to OA's it pushes up the IPAP due to the PS.