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My opinion:

I think you guys are giving that NRAH circuit way too much play priority, it has many more circuits that can throw a monkey wrench into that circuit long before the NR flag ever gets thrown. That NRAH circuit is more an exception circuit (in the absence of other events such as snore, FL etc.)

As mentioned, that NRAH circuit is dependent on current pressure and assumes there is nothing else going on such as snore, FL etc. if that NRAH circuit was used as suggested (in priority) we would be seeing many more NR flags thrown on reports we see come by here.

If you get 1 or 2 of those NR flags thrown per session you have a major problem with the machine differentiating your SDB events. Don't forget it drops pressure automatically by -2 cm, then it "holds", that means it may not re-enable that circuit for a set time period, during that hold period other circuits can take priority such as snore circuit which can easily give it the green light to further increase pressure. Now the snore circuit has a similar back-stop, if snore doesn't go away after 3 pressure increases it will lock out that circuit as well (as opposed to other machines which will continue to increase pressure chasing snore until it blows the top of your head off and/or runs into the max pressure setting).

We can also not assume that every 6 AH events seen in a row will cause a NR flag to be thrown and the pressure to drop by -2, if that were the case you should easily see distinct patterns of this on EncorePro reports, 3 stair-step increases in pressure followed by a -2 cm drop followed by hold period.

Also mentioned if your 90% pressure is consistently under 10 cm, you will most likely never see a NRAH flag thrown. If you study the circuits in that machine as it cycles through them you will see it likes to use that pattern for exceptions, for example in the presence of large leak it will drop pressure by -2 cm and hold. Same for snore, if snore persists, it drops pressure by -2 and hold.

Snoredog wrote:I think you guys are giving that NRAH circuit way too much play priority

More employed for analysis because Respironics attributes NRAH strategy as a way to work above an industry-acknowledged 10-cm central induction barrier.

Snoredog wrote: If you get 1 or 2 of those NR flags thrown per session you have a major problem with the machine differentiating your SDB events. Don't forget it drops pressure automatically by -2 cm, then it "holds", that means it may not re-enable that circuit for a set time period, during that hold period other circuits can take priority such as snore circuit ...

Right. This reiterates or nicely demonstrates my point: That 2 cm drop is driven by industry-acknowledged central-induction concerns.

If a snore occurs, there is plenty of respiratory effort accompanied by obstruction... therefore entirely adequate means of obstructive-versus-central differentiation has just occurred! Thus the algorithm has absolutely instant incentive to drop all that caution and fear about central induction. Of course that AHNR routine gets dropped once adequate obstructive differentiation methods finally occur. Quickly drop that unnecessarily central-cautious routine, of course!

snoredog wrote:Same for snore, if snore persists, it drops pressure by -2 and hold.

This has to do with avoiding pressure runaway and with avoiding pressure increases that yield no benefit. Again, the avoidance of pressure increases that yield absolutely no benefit have to do with an industry-acknowledged avoidance of static-pressure based homeostatic maladaptation---as well as obvious comfort benefits.

I'm not giving NRAH more real-time play than it deserves IMO. It's simply that part of the algorithm Respironics most clearly attributes to getting around that industry-acknowledged 10 cm statistical barrier regarding pressure induction. Even backing off from pressure for overly-persistent snore speaks of that same industry-wide concern about avoiding more static pressure than necessary: if a pressure increase yields no benefit, then back off for either comfort and/or central avoidance in all cases.

-SWS wrote:

Snoredog wrote:I think you guys are giving that NRAH circuit way too much play priority

More employed for analysis because Respironics attributes NRAH strategy as a way to work above an industry-acknowledged 10-cm central induction barrier.

Snoredog wrote: If you get 1 or 2 of those NR flags thrown per session you have a major problem with the machine differentiating your SDB events. Don't forget it drops pressure automatically by -2 cm, then it "holds", that means it may not re-enable that circuit for a set time period, during that hold period other circuits can take priority such as snore circuit ...

Right. This reiterates or nicely demonstrates my point: That 2 cm drop is driven by industry-acknowledged central-induction concerns.

If a snore occurs, there is plenty of respiratory effort accompanied by obstruction... therefore entirely adequate means of obstructive-versus-central differentiation has just occurred! Thus the algorithm has absolutely instant incentive to drop all that caution and fear about central induction. Of course that AHNR routine gets dropped once adequate obstructive differentiation methods finally occur. Quickly drop that unnecessarily central-cautious routine, of course!

snoredog wrote:Same for snore, if snore persists, it drops pressure by -2 and hold.

This has to do with avoiding pressure runaway and with avoiding pressure increases that yield no benefit. Again, the avoidance of pressure increases that yield absolutely no benefit have to do with an industry-acknowledged avoidance of static-pressure based homeostatic maladaptation---as well as obvious comfort benefits.

I'm not giving NRAH more real-time play than it deserves IMO. It's simply that part of the algorithm Respironics most clearly attributes to getting around that industry-acknowledged 10 cm statistical barrier regarding pressure induction. Even backing off from pressure for overly-persistent snore speaks of that same industry-wide concern about avoiding more static pressure than necessary: if a pressure increase yields no benefit, then back off for either comfort and/or central avoidance in all cases.

According to Respironics' algorithm training program:

Above 8 cmH2O pressure, the pressure increase for sustained apneas/hypopneas is limited to 3 cmH2O above the pressure setting at the onset of the apnea/hypopnea sequence. The pressure setting at the onset of the sequence is called the "Onset Pressure." The pressure 3 cmH2O above the "Onset Pressure" is called the "NRAH Threshold." "NRAH" is an acronym for "Non-Responsive Apnea/Hypopnea."

When the device encounters a non-responsive apnea or hypopnea, it will decrease pressure by 2 cmH2O and hold the pressure for 15 minutes. During this 15-minute "NRAH-hold" period, the pressure will be changed only in response to detection of a sequence of vibratory snore events. The reason for this increase in pressure followed by a decrease in pressure when an apnea/hypopnea is not responsive is to allow the device to respond appropriately to an event that is not treatable by increases in pressure, such as a central apnea.

After seeing two Hypopneas, the algorithm increases the pressure by 1 cmH2O, and the Onset Pressure resets to this new pressure level.

However, the Onset Pressure can not be raised above 12 cmH2O by a sustained string of Hypopnea-only events. This does not imply that the Onset Pressure value can not be set above 12 cmH2O. It only states that the Onset Pressure can not be <b>RESET</b> above 12 cmH2O due to a string of Hypopnea-only events. The maximum NRAH Threshold due to a sustained string of Hypopnea-only events will be 3 cmH2O above 12 cmH2

O.

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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, Hypopnea

ozij wrote:According to Respironics' algorithm training program:

Above 8 cmH2O pressure, the pressure increase for sustained apneas/hypopneas is limited to 3 cmH2O above the pressure setting at the onset of the apnea/hypopnea sequence. The pressure setting at the onset of the sequence is called the "Onset Pressure." The pressure 3 cmH2O above the "Onset Pressure" is called the "NRAH Threshold." "NRAH" is an acronym for "Non-Responsive Apnea/Hypopnea."

When the device encounters a non-responsive apnea or hypopnea, it will decrease pressure by 2 cmH2O and hold the pressure for 15 minutes. During this 15-minute "NRAH-hold" period, the pressure will be changed only in response to detection of a sequence of vibratory snore events. The reason for this increase in pressure followed by a decrease in pressure when an apnea/hypopnea is not responsive is to allow the device to respond appropriately to an event that is not treatable by increases in pressure, such as a central apnea.

After seeing two Hypopneas, the algorithm increases the pressure by 1 cmH2O, and the Onset Pressure resets to this new pressure level.

However, the Onset Pressure can not be raised above 12 cmH2O by a sustained string of Hypopnea-only events. This does not imply that the Onset Pressure value can not be set above 12 cmH2O. It only states that the Onset Pressure can not be <b>RESET</b> above 12 cmH2O due to a string of Hypopnea-only events. The maximum NRAH Threshold due to a sustained string of Hypopnea-only events will be 3 cmH2O above 12 cmH2

O.

[quote="-SWS"]Excellent post, Bill! Yes, I absolutely agree that we all benefit by topic exploration. That's the basis by which I also feel it will be both interesting and beneficial to further pursue that line of inquiry regarding cork-style blockages.

An industry-recognized and well-documented caution about a statistical 10-cm barrier (mentioned by Respironics, Resmed, PB, et al) is exclusively about central induction---at least according to all literature I have ever read. That doesn't mean they haven't missed something IMO.

Just out of curiosity has anyone managed to find documentation about the cork-style tongue blockages relative to pressure-delivery strategy? I can't turn any up and I am not interest-vested either. And I'm virtually positive vacuum-based occlusions do sometimes occur.

I personally feel that all PAP therapy is destined to either: 1) nicely avoid this problem in the first place (ideally this happens in most cases), or to 2) simply wait for good old mother nature's survival imperative to clear that problem once it does occur (thus some people may be bad candidates for PAP treatment if this hypothetical physiology problem really does occur frequently for them despite PAP).

I just can't see hypothetically-administered quick but small APAP pressure increases either aggravating this problem or successfully treating it---when mother nature is bound to rather quickly take over. But I too am open to reversing my views if what I happen to encounter what I think is compelling evidence.

Indeed, Bill: ego-maintained positions and limits of human intellect are both veritable truth-hiders. Well said!!!

ozij wrote:According to Respironics' algorithm training program:

<sniped for brevity>

Ozij,

As usual, very good data, very pertinent & well assembled for easy reading.

Thanks

DSM

-SWS wrote:
<snip>

Just out of curiosity has anyone managed to find documentation about the cork-style tongue blockages relative to pressure-delivery strategy? I can't turn any up and I am not interest-vested either. And I'm virtually positive vacuum-based occlusions do sometimes occur.

I personally feel that all PAP therapy is destined to either: 1) nicely avoid this problem in the first place (ideally this happens in most cases), or to 2) simply wait for good old mother nature's survival imperative to clear that problem once it does occur (thus some people may be bad candidates for PAP treatment if this hypothetical physiology problem really does occur frequently for them despite PAP).

<snip>

SWS,

What types of OSA occlusions are there that are not vacuum based ?

You have me on this point - are you considereing heavy snoring as 'pulsed occlusions' or something similar ?

I thought Sullivan's whole work began with his realization that people were suffering particularly (at worst) from vacuum based occlusions and that by splinting the airway with his initial basic CPAP, he found a cure & started an industry. We know that these occlusions have pre-cursor events (snores, flow-lims, hypops) and that as time has passed & technology improved & experience grown, sampling these is now used to add sophistication to splinting of the airway in ways that attempt to eliminate the multitude of negative side effects that CPAP causes (aerophagia, complex apnea, mask leak intrusion, excessive arousals, etc:).

DSM

-SWS wrote:Just out of curiosity has anyone managed to find documentation about the cork-style tongue blockages relative to pressure-delivery strategy?

dsm wrote:What types of OSA occlusions are there that are not vacuum based ?

Good point, Doug! We shall have to distinguish between a tightly wedged cork that is hopelessly stuck in a bottle and a typical scored apnea. Glad you brought that up!

Cheers! .

My take on the Respironics details nicely provided by ozij:

ozij wrote:According to Respironics' algorithm training program:

Above 8 cmH2O pressure, the pressure increase for sustained apneas/hypopneas is limited to 3 cmH2O above the pressure setting at the onset of the apnea/hypopnea sequence. The pressure setting at the onset of the sequence is called the "Onset Pressure." The pressure 3 cmH2O above the "Onset Pressure" is called the "NRAH Threshold." "NRAH" is an acronym for "Non-Responsive Apnea/Hypopnea."

Respironics refers to this NRAH logic as a method of safely working with obstructive events above the 10cm central-induction barrier: http://sleepapnea.respironics.com/techn ... logic.aspx

Toward observance of that statistical risk, we can see from the above text that three 1cm increments are allowed above onset pressures of 8 cm (resultant 11cm-20cm). The three 1cm limit is not imposed at onset pressures below 8cm, because of significantly lessened statistical risk of central-induction.

While further quoting Respironics ozij wrote:When the device encounters a non-responsive apnea or hypopnea, it will decrease pressure by 2 cmH2O and hold the pressure for 15 minutes. During this 15-minute "NRAH-hold" period, the pressure will be changed only in response to detection of a sequence of vibratory snore events. The reason for this increase in pressure followed by a decrease in pressure when an apnea/hypopnea is not responsive is to allow the device to respond appropriately to an event that is not treatable by increases in pressure, such as a central apnea.

Snore constitutes adequate means to differentiate respiratory effort. Thus there is no need to continue the cautious pressure-holding pattern relative to central-induction.

While further quoting Respironics ozij wrote:After seeing two Hypopneas, the algorithm increases the pressure by 1 cmH2O, and the Onset Pressure resets to this new pressure level.

However, the Onset Pressure can not be raised above 12 cmH2O by a sustained string of Hypopnea-only events. This does not imply that the Onset Pressure value can not be set above 12 cmH2O. It only states that the Onset Pressure can not be <b>RESET</b> above 12 cmH2O due to a string of Hypopnea-only events. The maximum NRAH Threshold due to a sustained string of Hypopnea-only events will be 3 cmH2O above 12 cmH2

These are the differences in the patent description that Bill cited earlier between apnea handling and hypopnea handling. I believe the differences to be based on statistical risk regarding central induction.

Regardless, we still have the first hypopnea event cautiously discarded (same cautious beginning strategy in both cases). Then we have a slow, safe pressure increase (same cautious middle strategy in both cases with the exception of the following). However, a limited reiterative lengthening toward that end-phase in the pressure response is where the key differences lie between apnea and hypopnea handling. Note that in the hypopnea case, more than three pressure increments can occur if either initial/ongoing "onset pressure" happens to be below 12cm.

Here we see that hypopneas during low pressure get a bit more leeway, presumably based on lessened statistical risk. However, at onset pressures above 12cm, hypopneas are handled identically to apneas.

Thank you, ozij. Your details are great!

Some of you guys just need to make a career change and go get an Associates Degree in Respiratory Therapy/Technician at your local community college. The level of detail and technical prowess I see in this thread regarding SBD equipment is beyond the norm that would be considered for OSA patients.

Im serious!

Eric

MrGrumpy wrote: The level of detail and technical prowess I see in this thread regarding SBD equipment is beyond the norm that would be considered for OSA patients.

Im serious!

Eric

Still trying to catch up to everybody in my local apnea support group.

I think I'm going to transfer to your town where it sounds much easier to breathe at night... .

I've been playing around with that auto algorirthm simulation program.

One thing seeming to have got lost in the previous discussion is "what is a non-responsive A/H?" (or sustained A/H)?


A non responsive A/H is the apprearance of the second event within 3 minutes of the first [Edit for the sake of clarity:] when pressure is at the NRAH level. One apnea/hyponea at that level - nothing happens. A second, within 3 minutes, and bam, the pressure goes down.

Respironics is not concerned by "an event" but rather, like dsm said, a pattern of events. Above 8 cms/h2o it assumes that any sequence of obstructive events (or proclivity to obstructive events) should be resolved by a rise of pressure of up to 3 cm. IF the pressure is raised 3 times, and Apneas or Hypopneas or combinations still occur within 3 minutes of each other, the pressure will be dropped, and the machine will wait for a snore to indicate obstruction.

What we tend to call, and think of as "an urnesponsive apnes/hypopnea" is actually a pattern of "apneas or hypopneas that come freqently and with no snores therefore hint that raising the pressure did not bring about the response we wanted - a pattern of smooth breathing"

And back to rooster question: How come higher pressure makes apneas shorter? I would say: they are shorter because the airway collapse is hindered by the air pressure. Sort of like a person who would fall badly if they didin't have crutches. They are still more liable to fall down when using crutches - but with crutches their stumbles won't be as bad, and will happen less frequently as well.

O.
Edited for the sake of clarity after I saw my message quoted (as it then really was) -in -SWS's following message...
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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, auto

-SWS wrote:

-SWS wrote:Just out of curiosity has anyone managed to find documentation about the cork-style tongue blockages relative to pressure-delivery strategy?

dsm wrote:What types of OSA occlusions are there that are not vacuum based ?

Good point, Doug! We shall have to distinguish between a tightly wedged cork that is hopelessly stuck in a bottle and a typical scored apnea. Glad you brought that up!

Cheers! .

Now SWS,

I am not in any way defending the cork tightly wedged idea - I got into that analogy merely to focus thinking around the idea of something (throat tissue / tongue / etc:) being at one end of the airway & the lungs (vacuum) being at the other & the lungs trying to get air but the throat/whatever blocking the way.

Again I remind us of what Sullivan discovered - all the physiological complexity & technical sophistication came later. He started with occlusions brought on by respiratory effort that caused the now well understood SpO2 drops.

So I won't be buying into any specific discussion on corks stuck tightly into necks of anything but will buy into 'occlusions brought on by the collapse / blocking of the airway during sustained respiratory effort'

DSM

DSM

ozij wrote: One thing seeming to have got lost in the previous discussion is "what is a non-responsive A/H?" (or sustained A/H)?

A non responsive A/H is the apprearance of the second event within 3 minutes of the first above pressure is at the NRAH level. One apnea/hyponea at that level - nothing happens. A second, within 3 minutes, and bam, the pressure goes down.

I think I agree with the above, but I'm not sure. Looking at the graph below, let's define that the three-minute window is not the entire graph, from left to right. Rather the three-minute window is a running limit or "time out" period, after which pairs of apneas are no longer associated as being "first and second apneas" (as a traveling pair). To examine the graph below, we have exactly four such running windows, with each "three-minute-or-less" window having produced pairs of A and/or H events:

Above we have the first three-minute-or-less window with paired events just to the left of the first red arrow. Precisely at that red arrow is where the second of those two A/H events occurred. So you'll note the first event of that pair does not receive a pressure response.

The second three-minute-or-less window occurs between the first red arrow and the second. Within that second time-limited window, the first A/H event occurs somewhere/anywhere after the first red arrow. But the second of those paired events occurs exactly at the second red arrow. Again, it's that second event that causes our next pressure increase.

So in this graph, it can take up to nine minutes, via three pressure increments, before that NRAH threshold is reached and that 2 cm pressure drop occurs. In the case of strictly hypopneas, it can take longer than nine minutes to reach, since "onset pressure" is reset at pressures below 8 cm.

Agreed that the entire string of events is what Respironics considers "non responsive". On the graph above the sixth event causes us to reach the NRAH pressure limit. The seventh event sits graphically unidentified (to us) on that topmost plateau. Then the eighth event triggers that 2 cm pressure drop. The entire string of events are deemed "non responsive".