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RERA Problem
#21
(10-31-2016, 04:02 AM)holden4th Wrote: When I was using the S9 which had no RERA reporting my CAs were a lot higher and I wonder if some of these are what are now being reported as RERAs.
Probably not. The S9 scores CAs when the airflow into your lungs drops by at least 80% and the FOT algorithm indicates the airway is not blocked.

The PR S1 Auto that you are using scores a RERA when there is a sequence of breaths that show increasing respiratory effort (i.e. the inhalations are "subtly distored" and the sequence ends with so-called "recovery" breaths---2 or 3 inhalations that are significantly larger than the running baseline indicates they should be. The drop in airflow during a RERA is less than 50% of the running baseline.

If the airflow drops by 50-80%, the PR S1 will score a H instead of a RERA. If the airflow drops by more than 80%, the PR S1 will score an OA or a CA depending on the result of the PP test.

Quote:The machine doesn't seem to respond to RERAs in any way at all yet some of these events lasted for close to a minute.
The PR S1 Auto algorithm is designed to increase the pressure ONLY when two or more RERAs or RERAs mixed with Hs and/or OAs occur within a two minute period. And the machine increases the pressure after the second event ends. So if you have one longish RERA that is isolated from other events, it would be expected that the PR S1 would not increase the pressure in response to the one event.

Same thing happens to long Hs and long OAs if they are isolated. And this lack of response to an isolated event follows the guidelines for a manual titration PSG in the lab. The idea is that if there's only an isolated event and the breathing stabilizes on its own, then additional pressure is probably not needed. But if two or more events occur in a 2 minute window, that is evidence that the airway is not stable and more pressure is needed.

Another difference between the PR Auto algorithm and the Resmed Auto algorithm is that the PR algorithm increases the pressure by 1cm in response to 2 events that are close together and then it waits for a minute or two to see if the breathing stabilizes. If more events occur, the machine will increase the pressure by 1cm again at the end of the waiting period, and then wait to see if the breathing stabilizes. The Resmed algorithm will raise the pressure after the second event and if more events continue to occur, it will continue to raise the pressure after each event. It stops raising the pressure only after the cluster ends. The result is that the Resmed is more aggressive about raising pressure during a nasty event cluster. However, the PR machine is the one following the guidelines for a manual titration: In a PSG the tech is supposed to give the breathing a chance to stabilize after each 1cm increase in pressure. This is done in order to minimize the chances of over titrating an individual.


Quote:I'm determined to beat these RERAs. I am thinking that if I can then I go to a whole new level of good sleep.
Like any other number, there is often a point beyond which there is no discernible difference in the numbers. In other words, you may find that the things you need to do to reduce your already acceptable RERA Index (2.05) to something close to 0, messes up your sleep in other ways.

For example, you write:
Quote:I don't really care if CAs go up as most of mine in the past were SWJ.
An increase in the CAI caused by a pressure increase may indicate that when you increase the pressure past a certain point, you have more fragmented sleep (ie more SWJ). The CAs might not be real, but the increase in SWJ is real and if you have a lot of SWJ during the night, you don't wake up feeling the way you should in the morning.

The key takeaway: You want to find a pressure that allows you to sleep well throughout the night (i.e. little or no SWJ) and keeps all the numbers in acceptable ranges. If the RDI = AHI + RERA I is below 5.0 and you have little or no evidence of SWJ breathing during the night and you wake up feeling pretty decent, then chasing a lower RDI at the expense of increasing the SWJ is not going to make you feel better in the long run.
Questions about SleepyHead?
See my Guide to SleepyHead
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#22
Hello Robysue, I've been waiting for you to enter this discussion so thank you for posting. The way I read your description; an RERA event is close to an Hypopnea and an H is close to an OA - a breathing event hierarchy as it were. Is this right?

I'm averaging between 15 and 20 RERAs per night and from what you say this is acceptable. While I feel a lot better in the morning than if I'd had no therapy at all, I still don't feel as refreshed as I would like to be. Advice from others seems to indicate that a slight increase in minimum pressure will help decrease RERAs. On the S9 I was running APAP 11-15 and it worked quite well but only rarely gave me one of those "I feel great" days. At the moment I'm at 10.5-16 and using AFlex which has a different way of responding to exhalation relief from what I can gather. The EPR of the S9 seems to be the same as CFlex and I wonder if I should try that out.

I'll bump the minimum pressure up by .5 tonight to 11.0 and see what that does. I'll wait untill the weekend to change from AFlex to CFlex. I'd rather feel like crap during the weekend as opposed to the week when I work with children.

One last question - how do I determine RDI? I'm not sure that SH displays this but I'm not sure.
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#23
(11-01-2016, 04:04 AM)holden4th Wrote: Hello Robysue, I've been waiting for you to enter this discussion so thank you for posting. The way I read your description; an RERA event is close to an Hypopnea and an H is close to an OA - a breathing event hierarchy as it were. Is this right?
Yes, more or less a RERA is a "Hypopnea with arousal" wannabe the same way a Hyponea is a OA wannabe.

More technically:
On a PSG, a RERA is closer to a "Hypopnea with arousal" than a "Hypopnea with a 4% O2 desat", but it fails to meet the criteria required to score a hypopnea with arousal. It might be less than 10 seconds long, or more typically, the airflow does NOT drop by the required 50% needed to score a hypopnea with arousal, even though there is evidence of increased respiratory effort---i.e. the breathing before the arousal is not normal sleep breathing. A RERA is usually NOT associated with an O2 drop since you "wake up" (i.e. arouse) before an O2 drop can occur.

In a sleep test, a RERA requires an arousal. Without the arousal, you don't have a real RERA. Your machine is inferring that an arousal took place on the evidence of so-called "recovery breaths". In other words, the machine is looking for a sequence of flow limited breathing (distorted inhalations) that does NOT meet its criteria for scoring a hyponea and the sequence of flow limited breaths ends with 1-2 recovery breaths and an immediate return to "normal sleep breathing".

Hyponeas are scored any time the airflow drops below 50% of the running baseline for airflow, but stays above 20% of the running baseline AND the airflow drop lasts for at least 10 seconds. The machine does NOT need evidence of "recovery breaths" at the end of the restricted airflow to score an H, but when you look at the data, Hs frequently (but not always) end with recovery breaths.


Quote:I'm averaging between 15 and 20 RERAs per night and from what you say this is acceptable.
What's your RERA I + AHI look like?


Quote:While I feel a lot better in the morning than if I'd had no therapy at all, I still don't feel as refreshed as I would like to be. Advice from others seems to indicate that a slight increase in minimum pressure will help decrease RERAs.
It may help decrease the RERAs, if they're real RERAs and the additional pressure doesn't cause other problems.

In other words, if you increase the pressure and the RERAs go down but the CAs go up, you may just be exchanging one problem for another. Likewise if the RERAs go down, but any aerophagia you have increases, you may just be exchanging one problem for another.

But if increasing the pressure a bit doesn't disturb the subjective quality of your sleep, then sure, a small 0.5-1.0 cm increase in pressure may be useful.


Quote:On the S9 I was running APAP 11-15 and it worked quite well but only rarely gave me one of those "I feel great" days.
Some of us never have "I feel great" days. At least in terms of how we feel when we wake up.

At a certain point you have to start looking for things other than under treated OSA/UARS and CPAP problems for the cause of not why we're not feeling as well as we'd like. You start with the usual suspects of
  • sleep schedule, sleep hygiene, and other sleep issues
  • other medical conditions and the medicines needed to treat them
  • lifestyle issues such as how well you're eating and whether you're getting enough exercise, along with how well you manage day-to-day stress.

When do you know that you're at that point where further dial wingin' on the PAP is unlikely to do much to improve things? My own answer to that question is when all the following are true:
  • the AHI (or RDI if you have a lot of RERAs, relatively speaking) is consistenly below about 3.0
  • leaks are well controlled---i.e. they're neither long enough nor large enough to significantly affect the efficacy of your therapy and there's no evidence they're waking you up
  • you have a normal latency to sleep---i.e. you fall asleep within 10-20 minutes of masking up
  • you are not waking up with aerophagia on a regular basis (In my humble opinion, even MINOR aerophagia may be a significant cause for not feeling as well as you want to feel.)
  • you don't remember any wakes during the night and there's no evidence of any wakes during the night (like OFF/ON cycling of the machine)
  • you are getting enough sleep to meet your body's needs. (Americans are notorious for NOT getting enough sleep on a nightly basis.)
  • you've been PAPing every night, all night long for at least 3 or 4 months.


Quote:At the moment I'm at 10.5-16 and using AFlex which has a different way of responding to exhalation relief from what I can gather. The EPR of the S9 seems to be the same as CFlex and I wonder if I should try that out.
Neither AFlex nor CFlex is really comparable to EPR on the Resmed.

I don't have time to look up all the relevant images for CFlex, AFlex, and EPR, but here's an outline of how they differ:

EPR
EPR reduces the pressure by 1, 2, or 3cm for each and every exhalation, all night long. It reduces the pressure by the same amount as the EPR setting. In other words, EPR = 3 provides a 3cm drop in pressure at beginning of every exhalation.

EPR starts to raise the pressure back up to the current pressure setting very close to the end of exhale and it continues to increase the pressure through the part of the inhalation where you are taking the most air into your lungs. As the rate of inhalation starts to drop, EPR starts lowering the pressure and once you start exhaling, the pressure level quickly drops by the same amount as the EPR setting.

You can see this in action using SleepyHead: The Resmed machines record both the flow rate AND the mask pressure. If you zoom in on both graphs to the point where you can see individual breaths, you can trace how well the EPR affect on the mask pressure tracks your breathing.

As a result of what EPR does, it turns out that you don't actually spend much time with the mask pressure equal to the pressure level for the machine. In other words, if the pressure has been raised to 14cm and EPR = 3, you're spending a lot of time during each breath cycle at a pressure that is closer to 11cm than 14cm, and you only hit 14cm at the point of maximum inhalation effort or just past that point. In other words, the peaks on the Mask Pressure graph line up pretty closely with the peaks on the Flow rate graph.

Because of how EPR works and its strong similarity to how a Resmed bilevel machine switches between EPAP and IPAP, many people describe EPR as being similar to a bilevel with the pressure support setting equal to 1, 2, or 3. As a user of a PR BiPAP, I can tell you that the PR BiPAP feels very different (to me) than the Resmed AutoSet's EPR with EPR = 3. But that's just me and my somewhat oversensitive airway and stomach.


AFlex
Regardless of the AFlex setting, the drop in pressure may be as little as 0.5cm or as great as 2.0cm. The actual drop in pressure depends on how forcefully you are exhaling as well as the AFlex setting. In general, the more forceful you exhale, the greater the drop in pressure. And the higher the AFlex setting, the more likely the drop will be the maximum 2.0cm drop.

But AFlex is more complicated than just "how much does the pressure drop". With AFlex, there is "rounding" at both ends of the pressure drop. In other words, with AFlex turned on, the pressure starts to decrease (slightly) towards the end of the inhalation (similar to EPR). How early the pressure starts to drop is determined by the AFlex setting: The higher the AFlex setting, the earlier in the breath cycle the pressure drop starts. In other words, when AFlex is set to 3, the machine starts to drop the pressure a bit earlier in inhalation than when it starts to drop the pressure if the AFlex is set to 1.

When the start of the exhalation is detected, the machine rather suddenly drops the pressure down as far as it plans to reduce the pressure (under most circumstances this seems to be about 1.5cm, regardless of AFlex setting). The drop in pressure is supposed to be timed so that the minimum pressure level occurs at the same time as the maximum exhalation effort is reached. Unfortunately the PR machines do NOT record Mask Pressure data, so we cannot see this in action.

After the rate of exhalation starts to slow down, AFlex starts to raise the pressure back up to the current pressure setting. Towards the end of the exhalation, the machine will have typically raised the pressure about 1/2 way back up to the current pressure setting. Once the inhalation is detected, the machine rapidly raises the pressure all the way back to the pressure setting. The AFlex setting controls how early in the exhalation the pressure starts to increase. In other words, if AFlex is set to 3, the start of the pressure increase is a bit later in the exhalation than if AFlex is set to 2.

The major takeaway is this: Regardless of AFlex setting, the machine will start increasing the pressure about half-way through the exhalation. Some people find this annoying and to a few people (like me) it feels as though the machine is trying to force you to inhale before you're ready to inhale. A few people also feel that the machine may be trying to get them to exhale before they're done inhaling if the AFlex is set too high. But most people find one of the AFlex settings does a good job in tracking their inhalations/exhalations and "rounding" the pressure changes and these people do NOT feel like the machine is forcing them to inhale or exhale. The key is finding the correct setting, and that can only be done with trial and error.


CFlex
CFlex is a primitive form of AFlex. Like AFlex, the drop in pressure may be as little as 0.5cm or as great as 2.0cm regardless of the Cflex setting. Like AFlex, the actual drop in pressure depends on the forcefulness of the exhalation as well as the CFlex setting. In general, the more forceful you exhale, the greater the drop in pressure. And the higher the CFlex setting, the more likely the drop will be the maximum 2.0cm drop.

But the timing of the increase back to the current pressure level on the machine is very different than AFlex and there is no "rounding" at the end of the inhalation.

CFlex waits until the beginning of the exhalation is detected and then it rapidly drops the pressure by what it regards as appropriate based on the force of exhalation and the CFlex setting. The maximum drop in pressure is supposed to be timed so that the minimum pressure level occurs at the same time as the maximum exhalation effort is reached.

Like AFlex, CFlex starts increasing the pressure during the second half of the exhalation. However CFlex raises the pressure all the way back up to the therapeutic pressure level before the inhalation starts. That is VERY different from both AFlex and EPR. And for some people that increase in pressure during the second half of the exhalation definitely feels like the machine is trying to force them to inhale before they're done exhaling. Other people don't have any problem with this once they tune in on which CFlex is most comfortable for their particular breathing pattern.



Quote:I'll bump the minimum pressure up by .5 tonight to 11.0 and see what that does. I'll wait untill the weekend to change from AFlex to CFlex. I'd rather feel like crap during the weekend as opposed to the week when I work with children.
Sure, bump the min pressure up a bit and leave it at the new setting for at least a week before you make any decisions about what to do next.

Personally I would NOT recommend changing from AFlex to CFlex. Most people find CFlex much less comfortable than AFlex. The only exception to this is if you feel like AFlex is reducing the pressure too soon and that is causing you to feel air starved when you are awake.


Quote:One last question - how do I determine RDI? I'm not sure that SH displays this but I'm not sure.
Somewhere in the settings you can control whether SH reports RDI or AHI. But there's no need to change the settings:
  • RDI = AHI + RERA I

Just add your AHI and RERA I numbers together and you'll get the RDI.

Questions about SleepyHead?
See my Guide to SleepyHead
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#24
holden4th,

A quick question: Why did you switch from the Resmed S9 AutoSet to the PR System One Series 60 AutoCPAP?

And when you were using the S9, do you remember what the EPR setting was?
Questions about SleepyHead?
See my Guide to SleepyHead
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#25
Hello Robysue.

The S9 was a loaner. A bargain deal came up for the PR and I took it after carefully looking at reviews etc. My EPR setting on the S9 was 2.

Thank you for all the info in the preceding post. I'm someone who likes as much info as possible to come up with my own idea as to what is happening and your description of the EPR vs AFlex process has given me a lot to think about. I'm sure other would also benefit and maybe this post should be a sticky note.

Last nights AHI was 1.39 and conicidentally so was the RERA index. This gives me an RDI of 2.78. Other nights have had RDIs of between 3 and 4.5. What this means I'm not sure but based on your post some tweaking of the machine might help.

Last night I got up and when I went back to bed I fell asleep before putting the mask back on. I woke up again 2 hours later and remedied that and didn't feel quite as bad as I thought I would.

Here's how I meet your criteria

the AHI (or RDI if you have a lot of RERAs, relatively speaking) is consistenly below about 3.0 - not happening yet
leaks are well controlled---i.e. they're neither long enough nor large enough to significantly affect the efficacy of your therapy and there's no evidence they're waking you up the data says there is no problem here
you have a normal latency to sleep---i.e. you fall asleep within 10-20 minutes of masking up. I drop off quite quickly
you are not waking up with aerophagia on a regular basis (In my humble opinion, even MINOR aerophagia may be a significant cause for not feeling as well as you want to feel.) Not sure what Aerophagia feels like but don't think it's an issue
you don't remember any wakes during the night and there's no evidence of any wakes during the night (like OFF/ON cycling of the machine) No recollection apart from some lucid dreaming
you are getting enough sleep to meet your body's needs. (Americans are notorious for NOT getting enough sleep on a nightly basis.) Usually get over 8 hours
you've been PAPing every night, all night long for at least 3 or 4 months. Yes.

I'll up the pressure and see what happens over the next week. AFlex is here to stay.

Once again, thanks for the input - you're understanding of so many issues is outstanding.
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