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

[Sleeprider]

This may be futile, but I'm going to try anyway. When a CPAP titration is done, it tends to be a high pressure compared to titration on bilevel, because a single pressure is required to resolve OA, and H (including obstructive flow limits that result in hypopnea and RERA). A bilevel titration will generally be lower, with EPAP titrated to treat OA and pressure support for other events. A common bilevel titration protocol is that EPAP is increased until CA is controlled and where SpO2 is low, EPAP is increased for PEEP (positive end expiratory pressure) which increases O2 saturation, and IPAP (EPAP+PS) is used for hypopnea, ventilation and other objectives.

When a Resmed CPAP or APAP is setup to use EPR, It will not usually hurt treatment efficacy, UNLESS the titrated pressure is critically low. This can happen in simple OSA that is resolved at low pressures. Similarly, people that are self titrating and using low pressure, can end up "stuck" at 4 cm CPAP pressure when CPAP pressure is under 7, and EPR is at 3.

I think Sleepster's CPAP titration of 13 clearly falls into the category of a conservative titration. Using Auto CPAP, he could easily set his pressure lower, and the auto algorithm would increase pressure high enough to prevent most apnea. Using EPR, his obstructive apnea was fully treated and the "pressure support" provided good results for hypopnea. The use of bilevel with EPAP min 5.2, EPAP max 9.2 and PS 4.4 (IPAP 13.6) show just how conservative his original titration was.

I think we are arguing semantics here. I believe that the Resmed CPAPs provide therapy equivalent to a bilevel limited to 3-cm pressure support, and that the titration principles for bilevel are applicable. Those titration approaches will not work with a Respironics machine which must be titrated as a conventional CPAP with conservatively high minimum pressures. The pressure relief on a Respironics CPAP is not equivalent to bilevel because it returns to the CPAP pressure before inspiration begins.

[Reznik]

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.

I'm really glad you stuck around!

To the extent that the patient suffers from hypopneas that require a higher pressure to resolve than the OSA pressure, I agree with you. 

But, if that were the case, I'd hope that the sleep technician would enable EPR to obtain the benefits of the EPAP, IPAP, and pressure support, rather than just sending the patient out the door with a titration that was higher than necessary on expiration.

[Sleeprider]

I'm not aware of any CPAP titration that even discusses the use of bilevel parameters, or EPR.  I have seen Flex mentioned.

[Reznik]

This may be futile, but I'm going to try anyway.

...

I believe that the Resmed CPAPs provide therapy equivalent to a bilevel limited to 3-cm pressure support, and that the titration principles for bilevel are applicable.  Those titration approaches will not work with a Respironics machine which must be titrated as a conventional CPAP with conservatively high minimum pressures.  The pressure relief on a Respironics CPAP is not equivalent to bilevel because it returns to the CPAP pressure before inspiration begins.

I think you and I have been in agreement on almost everything since the beginning, and I agree with you now as well, with one exception:

With Respironics, regular C-Flex works as you indicate.  However, A-Flex/C-Flex+ do NOT return to inspiration pressure before inspiration begins.  According to the documentation, A-Flex/C-Flex+ looks like Bi-Flex, but with a 2cm level of Pressure Support (no matter which EPR setting you use).   

I posted a link to the manual that so indicates in another thread.  Did you see it?

[Reznik]

I'm not aware of any CPAP titration that even discusses the use of bilevel parameters, or EPR.  I have seen Flex mentioned.

Read the ResMed Sleep Lab Titration Guide.  There's a detailed discussion of EPR and what it does, including wave forms, on page 20.  It's also mentioned in the CPAP Titration Protocols on page 33.  The first step is "EPR comfort setting - Set to patient comfort (1, 2, or 3)."  

That mean nothing, however, if the technician starts at 4.0cm, as recommended by the protocols, since the patient won't see any EPR until the IPAP climbs above 4.0cm.

[Sleeprider]

I missed the link that shows the behavior of CFlex+/AFlex, and I've looked. Give me another shot if it's handy.

The titration protocols I've seen in sleep studies tend to deal with straight CPAP pressure or simple bilevel, and those are conducted as separate phases. All I see is a technician dialing through CPAP pressure in 1-cm increments and failing it after as little as 5 minutes. I have seen completed titrations with less than 1/2 hour of total time on the recommended pressure. The bilevel titrations always start at 4 cm PS and seem to increase PS for hypopnea, and EPAP for OA. Nearly every prescription is for fixed CPAP or BPAP pressure based on very little evidence of efficacy. That's why the forum works so well.

[Reznik]

I missed the link that shows the behavior of CFlex+/AFlex, and I've looked.  Give me another shot if it's handy.

The  titration protocols I've seen in sleep studies tend to deal with straight CPAP pressure or simple bilevel, and those are conducted as separate phases.  All I see is a technician dialing through CPAP pressure in 1-cm increments and failing it after as little as 5 minutes.  I have seen completed titrations with less than 1/2 hour of total time on the recommended pressure.  The bilevel titrations always start at 4 cm PS and seem to increase PS for hypopnea, and EPAP for OA.  Nearly every prescription is for fixed CPAP or BPAP pressure based on very little evidence of efficacy.  That's why the forum works so well.

I've sent you the links privately.

What you've described is SOP for CPAP and BiPAP titrations, according to the guides that I've read.  5 to 10 minutes is what the titration guides say to wait.  Depending upon the guide, one obstructive event in five minutes (or two in ten) is all that it takes to go up another 1cm in pressure.  Bi-Pap either starts at 4/8, or at the patient's prior CPAP level as IPAP with EPAP 4cm below.   

Come to think of it, that particular protocol supports your view that the CPAP titration results in a number that is higher than needed for obstructive events alone.  Instead, when converting to BiPAP, they assume that the CPAP level is the IPAP, and reduce the EPAP by 4.  

That makes an even more compelling case for the argument that EPR is just a mini-BiPAP.  It keeps the CPAP level as the IPAP and reduces the EPAP by 1, 2, or 3 as defined by the EPR setting.

[GoodSleepHunting]

Do you maybe know if Expiratory Relief from the F&P SleepStyle machine is the same as EPR from Resmed?

and do you think EPR on Resmed is better then flex?

[MrIvanDrago]

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.

You mentioned this in your post, "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."


Why would a pressure support of 3.0 cause problems? What type of problem would you typically experience with unneeded pressure support?

[MrIvanDrago]

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.

You mentioned this in your post, "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."


Why would a pressure support of 3.0 cause problems? What type of problem would you typically experience with unneeded pressure support?