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Isn't Resmed's Expiratory Pressure Relief really Inspiratory Pressure Support??
#61
RE: Isn't Resmed's Expiratory Pressure Relief really Inspiratory Pressure Support??
(11-24-2017, 05:00 PM)Sleepster Wrote: If a person is titrated at some pressure then it may be that pressures significantly lower will result in obstructions, but slightly lower will result in hypopneas. A hypopnea is, after all, just a less-severe obstruction than an obstructive apnea. Thus a person who turns on EPR and leaves the pressure alone will find no increase in hyponeas, and since the expiratory pressure is just a few centimeters lower, that reduction is not enough to result in an increase in obstructive apneas.

When they titrate, they pick the lowest pressure that is sufficient to reduce the number of obstructive apneas to 5 or less per hour.  So, if you reduce the pressure, even by a little, I'd expect to see the number of obstructive apneas increase to greater than 5 per hour.

A person who turns on EPR, without making any other adjustments, should experience more OA's, because their EPAP pressure (pressure on the display minus the EPR setting) would be lower than what their titration required.  They might also experience more centrals, because their pressure support (EPR level of 1, 2, or 3) would be higher than what they received before.  Their hypopneas would probably decrease, because they'd either be converted to obstructive apneas since the EPAP is lower than they need, or they'd decrease because they would be blasted open by the increased pressure support that comes on during inspiration, or both.

Based upon my own personal experience with Resmed's machines, with EPR on at 1, 2, and 3 while awake, the EPAP (machine's stated pressure minus EPR level) becomes the background pressure against which you become accustomed.  When you exhale, and in between breaths, you're constantly fighting EPAP.  You become accustomed to it and almost don't notice it anymore.  But, when you inhale, the IPAP comes on (1, 2, or 3 cm higher than the EPAP you've become accustomed to), it is like an additional blast of pressure that forces you to take a deeper breath than you otherwise would.  It's very hard to resist the pressure support because you're already breathing in.  

The higher the difference between IPAP and EPAP (i,e., the more pressure support), the greater the blast.  Too high a pressure support can cause you to take too many deep breaths, and your body will react by simply refusing to take additional breaths until it can restore the right balance between oxygen and carbon dioxide, i.e a central apnea.  Too low a pressure support, in the person who needs bi-level pressure support to get a sufficiently deep breath, can cause hypopnea.

This, again, is why I say that Resmed's implementation of EPR is a misnomer.  It really isn't expiratory pressure relief.  It is really inspiratory pressure support.  It is bi-level therapy with pressure support of 1, 2, or 3.

Again, this does not apply to Respironics C-Flex or Bi-Flex, which actually is expiratory pressure support.  It also does not apply to A-Flex/C-Flex+, which looks to me like Respironics attempt to match Resmed's EPR without getting sued for patent infringement.  And now that I think about it, I may have the legal aspects backwards.  It may be that C-Flex was first, which was truly expiratory pressure relief, and that Resmed wanted to offer a similar feature without violating Respironics patents, and so they created their EPR, which really isn't, and then Respironics decided to copy it without copying it exactly and came up with A-Flex/C-Flex+.  To find out for sure, we'd have to figure out which was introduced first...
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#62
RE: Isn't Resmed's Expiratory Pressure Relief really Inspiratory Pressure Support??
(11-24-2017, 05:28 PM)Reznik Wrote: When they titrate, they pick the lowest pressure that is sufficient to reduce the number of obstructive apneas to 5 or less per hour. 

I don't believe that. I think they have to also reduce the number of hypopneas.

I'm guessing that your "5 or less per hour" notion is taken from the clinical cut-off for mild OSA? That's an AHI of 5, and it includes both apneas and hypopneas.

Regardless, I don't think that number is used in that way during a titration. They will raise the pressure in an attempt to reduce the AHI, and hopefully they reach a pressure where continued increases in pressure produce no significant decreases in AHI.
Sleepster

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#63
RE: Isn't Resmed's Expiratory Pressure Relief really Inspiratory Pressure Support??
(11-24-2017, 05:28 PM)Reznik Wrote: A person who turns on EPR, without making any other adjustments, should experience more OA's, because [...]

But they very often don't. So what you think "should" be happening isn't.
Sleepster

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#64
RE: Isn't Resmed's Expiratory Pressure Relief really Inspiratory Pressure Support??
OK someone tell me if I'm wrong.

One of the reasons that a lower pressure can be used on exhale is because the air exhaled from the lungs assists in keeping the airway open.

The pressure on inhale has to be higher because it is the sole source that keeps the airway open.

The only time there is no assist on exhale is the pause before inhale begins.

Normally that short pause doesn't allow the airway to close that quickly. If it did than BPAP would not work.

What am I missing?
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#65
RE: Isn't Resmed's Expiratory Pressure Relief really Inspiratory Pressure Support??
(11-24-2017, 09:30 PM)Walla Walla Wrote: The only time there is no assist on exhale is the pause before inhale begins.

Normally that short pause doesn't allow the airway to close that quickly. If it did than BPAP would not work.

I think that for most people, that's probably true. Each person's anatomy is slightly different, so for some people it may not be true.
Sleepster

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#66
RE: Isn't Resmed's Expiratory Pressure Relief really Inspiratory Pressure Support??
Sleepster, In that case the person would have to use a fixed pressure. Is that right?
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Membership in the Advisory Members group does not imply medical expertise or qualification for advising Sleep Apnea patients concerning their treatment.



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#67
RE: Isn't Resmed's Expiratory Pressure Relief really Inspiratory Pressure Support??
(11-19-2017, 07:54 PM)Sleeprider Wrote: What all this means is you need to be aware of the impacts of using EPR or Flex.  Expect that with auto pressure, the pressure will be higher than your titrated CPAP pressure without pressure relief.

In my case and I suspect a lot of, if not most, others the pressure doesn't go up. I rarely if ever go above my titrated pressure of 13 cm regardless of how large I set my pressure support. Expect something to happen if you know for sure it doesn't happen?!
Sleepster

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#68
RE: Isn't Resmed's Expiratory Pressure Relief really Inspiratory Pressure Support??
(11-24-2017, 09:03 PM)Sleepster Wrote:
(11-24-2017, 05:28 PM)Reznik Wrote: When they titrate, they pick the lowest pressure that is sufficient to reduce the number of obstructive apneas to 5 or less per hour. 

I don't believe that. I think they have to also reduce the number of hypopneas.

I'm guessing that your "5 or less per hour" notion is taken from the clinical cut-off for mild OSA? That's an AHI of 5, and it includes both apneas and hypopneas.

Regardless, I don't think that number is used in that way during a titration. They will raise the pressure in an attempt to reduce the AHI, and hopefully they reach a pressure where continued increases in pressure produce no significant decreases in AHI.

Well, I agree that they also want to reduce hypopneas.

But, with respect to the use of "5 or less per hour," you're mistaken.  

The American Association of Sleep Technologists has published a "Summary of AASM Clinical Guidelines for the Manual Titration of Positive" as of 2012.  In section 2.2.1, it states:

"You have achieved an optimal titration when you see the following:

1. The Respiratory Disturbance Index (RDI) is < 5 per hour for a period of at least 15 minutes at the selected
pressure and within the manufacturer’s acceptable leak limit.
2. The SpO2 is above 90% at the selected pressure.
3. Supine REM sleep at the selected pressure is not continually interrupted by spontaneous arousals or
awakenings."

https://www.aastweb.org/hubfs/Technical%...6163811483
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#69
RE: Isn't Resmed's Expiratory Pressure Relief really Inspiratory Pressure Support??
(11-24-2017, 09:07 PM)Sleepster Wrote:
(11-24-2017, 05:28 PM)Reznik Wrote: A person who turns on EPR, without making any other adjustments, should experience more OA's, because [...]

But they very often don't. So what you think "should" be happening isn't.

I've read a lot of posts here that indicate that that people who turn off EPR DO experience more OAs.

For example:

http://www.apneaboard.com/forums/Thread-...rt-setting

http://www.apneaboard.com/forums/Thread-EPR-or-not-EPR

http://www.apneaboard.com/forums/Thread-...-necessary

In the last thread that I linked to, PaulaO2 indicated that "There's a trend slowly growing where sleep docs are not having them turned on for their patients because they feel it effects the AHI."

In cases where it is not happening, it may be that the person had a greater level of obstruction in the sleep lab than they do when sleeping at home.  They may really not need such a high pressure.  Turning on EPR will reduce their EPAP pressure, but keep their IPAP pressure higher - which they may not need.
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#70
RE: Isn't Resmed's Expiratory Pressure Relief really Inspiratory Pressure Support??
(11-24-2017, 09:30 PM)Walla Walla Wrote: OK someone tell me if I'm wrong.

One of the reasons that a lower pressure can be used on exhale is because the air exhaled from the lungs assists in keeping the airway open.

The pressure on inhale has to be higher because it is the sole source that keeps the airway open.

The only time there is no assist on exhale is the pause before inhale begins.

Normally that short pause doesn't allow the airway to close that quickly. If it did than BPAP would not work.

What am I missing?

You've got at least five misunderstanding going on here.

1.  When you breath out, that air does not give any boost in keeping the airway open.  As you add air, your CPAP blower slows down and reduces the amount of air that it is pushing at you by the same amount so that the pressure will remain the same.  If the CPAP machine didn't reduce the amount of air that it added to offset your expiration, then the pressure would go UP when you breath out.  The CPAP reduces the amount of air it pushes at you during expiration in order to keep the pressure measurement the same even when EPR is disabled.

2.  When EPR is enabled, the machine goes further and actually reduces the amount of air that it is pushing at you by an amount that is greater than the amount of air you're pushing at it.  That effects a reduction in air pressure in the system.  That reduction in pressure can cause the airway to collapse if the new, lower pressure is not sufficient to keep the airway open.

3.  The pressure at inhale does not have to be higher to keep the airway open.  Billions of people all over the world sleep without a CPAP and have the same pressure on inhale and exhale and manage just fine.  Those at sea level experience higher pressures than those at altitude.  And people with CPAP machines that don't enable EPR also manage to inhale without an increased pressure.  

All that is required to keep the airway open during inhale is to have the right pressure and keep the pressure the same.  The machine must add the exact same amount of air that your lungs take out in order to do that.  That's what a CPAP does.  It doesn't have to increase the pressure.  It just needs to maintain the pressure by pushing an amount of air into the system that matches the amount you've taken into your lungs (plus the mask leak rate, of course).

(This discussion refers to people who are prescribed CPAP.  Obviously, a person who needs BiPap therapy does need a higher IPAP in order to take a full breath)

4.  If you enable EPR (on a Resmed machine), it doesn't merely decrease the pressure on expiration.  It decreases the pressure ALL of the time, except during the period of time after you start inhaling and before you stop.

5.  BiPap works because it is EPAP (the lower number) that holds the airway open, and IPAP (the higher number) which forces the patient to take deeper breaths.  When EPR is enabled on a Resmed Airsense, the pressure displayed on the machine is IPAP.  The EPAP, which is not shown to the patient is the displayed pressure minus the EPR setting.

I hope this clarifies things.
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