EERS Experiment Data (sherwoga)

[slowriter]

This is an area for further discussion.  In post #37, JoeyWallaby gave an excellent discussion of EPR and PS in the context of using the EERS.  Others, especially Slowriter, added to the discussion in subsequent posts.  If I understood JoeyWallaby correctly, one experiment I could do is to incrementally increase my minimum pressure setting (without EERS) to see if and at what minimum pressure I experience the "significant" onset of CA events, say consistently greater than 5.  Then once I’ve created the problem with increased minimum pressure, see if I could add the 6 inch EERS and again eliminate the CA events. I would of course want to monitor both OA events and Flow Limitations throughout such an experiment and be prepared to abandon the experiment if necessary.  One reason I see for doing this experiment is that it might help develop the case that I really do need a bi-level or ASV pump.  Thoughts are welcome!

In the end, do you have a conclusion about what settings (pressure, EPR, EERS) work best for you on this machine, and how they impact how well you sleep?

I guess how much time you want to spend on your current machine vs experimenting with a bilevel is based in part on the answer to that question.

Your financial, insurance, and medical support situation would also be relevant.

[Sleeprider]

I'm impressed with the integrity of the statistical evaluation. Many of your conclusions confirm my heretofore anecdotal observations, particularly with CA response to EERS, flow limitation response to EPR or PS and respiratory minute and tidal volume responses to both. I think your experiment was of course limited by the size of the cohort, and the use of the Airsense 10 Autoset with its limited EPR, rather than an Aircurve 10 Vauto with much greater pressure support available. On that note, I would like to see EPR expressed as pressure support, because that is how we are using it, and I suspect the experimental design could be picked up with a true bilevel in the future.

Something you mentioned was the importance of a machine to measure flow limitation. This is a key feature of Resmed and is not reported by Philips. It is my understanding that Resmed records flow data on a 25 Hrz frequency compared to Philips 5 Hrz. As a result, OSCAR interpolates the low frequency data on Philips machines to a smooth the data, and of course inspiratory shape is difficult to resolve with low frequency data. An important point is that the Resmed CPAPs with EPR are capable of up to 3-cm pressure support, while Philips CPAP provide Flex which is not bilevel in nature. When Flex is enabled on Philips machines, CPAP pressure is reduced by up to 2-cm ahead of expiration, and CPAP pressure resumes before expiration ends and inspiration starts. While this is a logical strategy for CPAP, it greatly limits the use of Philips machines in treating flow limitation and hypopnea with pressure support, and means those machines are a pure-pressure play for therapy, while Resmed can be though of as a limited bilevel. This comment may be a bit off-topic for your experiment, but I thought it relevant to point out that this is not repeatable with Philips CPAP machines.

[sherwoga]

This is an area for further discussion.  In post #37, JoeyWallaby gave an excellent discussion of EPR and PS in the context of using the EERS.  ...

In the end, do you have a conclusion about what settings (pressure, EPR, EERS) work best for you on this machine, and how they impact how well you sleep?

I guess how much time you want to spend on your current machine vs experimenting with a bilevel is based in part on the answer to that question.

Your financial, insurance, and medical support situation would also be relevant.

Your questions go to the heart of the matter.  

No, I'm not there yet: I do NOT have the required conclusion.  

Some issues:

A) Pressure:  
With guidance from moderators, I ended up with a minimum EPAP of 5 cm H2O for this experiment.  It was derived from my Rx settings more than any insights into how its value might impact the outcome of the study.  It was NOT an experiment factor, but a constant.  Maybe it should have been a 3rd factor.  I'm not sure.  That being the case, I don't think I can answer the question about pressure at this point.

B) EPR and EERS: 
The very first recommendation I got regarding EPR (See Post from Fred Bounjour) was to lower it from 3 to 1.  This happened in early November well before I started the experiment and resulted in an immediate lowering of my CAI. And, since CAI is one term in the AHI, the AHI also came down. That low CA count operated throughout the experiment.  But Flow Limitations became more obvious.  Moderators made statements like: "Sherwoga's pressure is being driven by his flow limits".  The experiment suggests the need for EPR to control flow limits.  Other moderator statements have suggested that the EERS would allow larger EPR to minimize flow limits while limiting CA events. My thinking currently is admittedly confused, but I believe I want the highest EPR possible with some EERS (probably 6 inches). I remain uncertain whether to increase the minimum EPAP. I may need to scout that possibility and suggested such an experiment in my previous post.  Your feedback on that point, as well as, the feedback from others on that point would be appreciated.  

C) Medical support situation (impacts insurance and, therefore, financial):
I've seen my current pulmonologist only once in October 2019.  I went to him for a 2nd opinion because of doubts about my former pulmonologist.  It was a very good interaction during which he introduced me to the "clinical mode" available on my CPAP machine.  Without detail, that new awareness led me to the Apnea Board, OSCAR Software, making my EERS (with your assistance and that of others) and the experiment.  He did not have my Sleep Study Report until a few weeks after that appointment.  After he saw and presumably reviewed it, he had his nurse call to tell me NOT TO CHANGE anything on my machine as he thought the Rx was working.  If that were true I wouldn't have ever sought a second opinion in the first place.  My having experienced high AHI's without the benefit of any detail for the year and a half prior to my first appointment with him is what drove me to seek a second opinion.  By the time of that phone call I was already well into my EERS journey.  I.e., I had already been making a lot of changes with significant improvements.  So my assessment of him as a care provider and of our relationship is ambiguous.  Unless I ask for an earlier appointment my next appointment is April 15.  I have until then to either 
     1) resolve my sleep performance (good AHI with lowered flow limitations, improved flow patterns and diminished sleepiness) with or without the EERS, or 
     2) make the case that I need the bi-level or Vauto CPAP.  
The analysis of the experiment results is ongoing and MIGHT result in a plan to develop that case.  It was my hope that dialog with the moderators or other Apnea Board members at this point would result in additional insights into developing that plan.  Hence the purpose statement near the beginning of my previous post.  The Preliminary Report was for the purpose of generating dialog.  Your questions do of course contribute.  But what do you think about the experiment of sleeping with my current "doctor approved" Rx settings except for raising the minimum EPAP (i.e. raising minimum pressure from 8 to X) to encourage CA events (at least a little bit) and then in a second phase adding the EERS to see if they decrease without degradation of flow characteristics?

I do appreciate you taking  the time to read my tomes and hope they are adequately coherent.

[Gideon]

Raising pressure is considered a possible cause of CAI increase, a stronger increase would be from EPR increase. EPAP is what is used to manage Obstructive Apnea, thus I suggested that be a constant for the experiment. EPAP was maintained by modifying Min Pressure to compensate for the amount of EPR. This effectively made the machine a BiLevel up to a PS of 3.

The experiment maintained an EPAP of 5 cmw and varied PS of 0,1,2,3 and varied EERS of 0,6,12,18

Increasing PS is how to manage Flow limitations.
The issue is the increasing PS also increases the CAI
The increasing EERS should decrease the CAI
In the course of the experiment it was noted that EERS was sensitive to any mask leakage or "mouth breathing", anything that tended to flush the dead space.
The required treatment task is a 2 variable titration process between PS and EERS to manage hypopneas, flow limits, RERAs, and UARS
The possibility remains of having to manipulate the EPAP pressure to manage the OAI

[slowriter]

You could try a few nights at a min pressure of 9, EPR at 3, and the 6-iches of EERS, and see how your flow limitations look, and whether the EERS keeps your CAs in check?

My guess is FL is still significant enough you'll want to argue for a bilevel (the vauto), but you then have the additional data.

[Sleeprider]

The required treatment task is a 2 variable titration process between PS and EERS to manage hypopneas, flow limits, RERAs, and UARS
The possibility remains of having to manipulate the EPAP pressure to manage the OAI

Assuming we are in Autoset mode and not fixed pressure, this is unlikely to have a large effect unless Sherwoga is significantly below an effective therapeutic EPAP.  If it is fixed pressure, I agree. I’m reading on the phone so I’m not sure.

[sherwoga]

In my Preliminary Report on my Designed Experiment posted last week I discussed some of the trends I had observed.  Since then, I have completed the analysis of "Peak Flow Limits" and "Uncorrected CAI", both having been excluded in that report.  For the latter I simply took the CAI data reported by OSCAR without discounting any of the suspicious Central Events (what Fred Bonjour called Sleep Wake Junk).  

The trend for Peak Flow Limit paralleled that for 95% Flow Limits: Decreasing Flow Limits with Increasing EPR and no effect from EERS.  That reinforces the conclusion that I want as much pressure support as I can get or at least that I need more than I can get from my AirSense 10 Autoset.  

Not discounting the Sleep Wake Junk in my CA index gave statistically significant trends, too:

1. Increasing CAI with Increasing EPR
   
2. Decreasing CAI with Increasing EERS.  
   

Only the latter (2) parallels the trend reported before for the Corrected CAI where I did discount the Sleep Wake Junk per and with help from Fred Bounjour.  That is consistent with the expectation that the EERS would help eliminate Clear Airway events.  The former (1) was not apparent in the corrected CAI results.  IMHO this result is somewhat reassuring as the expectation is that pressure support enhances ventilation and lowers carbon dioxide in the blood leading, in the extreme, to hypocapnia observable as increased CAI.  In my mind, the jury is still out as to whether or not I should discount Sleep Wake Junk.  

After my rather long Preliminary Report, Slowriter wrote:

In the end, do you have a conclusion about what settings (pressure, EPR, EERS) work best for you on this machine, and how they impact how well you sleep? Post. 

My answer, verbose as always, was that no I didn't have a conclusion.  However, I met with my statistician again and we developed the following path forward to try to get to a conclusion.  I'm inserting my graphic of my designed experiment again for clarity.  This time a couple of the TCs (treatment combinations) are marked with colored arrows.  

   

1. Red Arrow corresponds to a TC that I was suspicious might be the best TC. It is a combination for which I had already acquired 10 good runs of data. Those runs were acquired during periods when progress on my experiment stalled for one reason or another and during which my plans were evolving. 
   
2. Green Arrow corresponds to the point that my statistician wants me to test next.
   
3. Purple Arrow corresponds to where I conclude I should test.  I ran this condition last night and am including screen shots later for discussion in the second part of this post.  
   

Path forward is to acquire four runs at the Purple Arrow and another four runs at the Green Arrow.  Since these are being acquired late in this experiment they are subject to problems that can arise when treatment combinations are not randomized.  In an effort to maintain the statistical integrity of the experiment I will add another two runs from somewhere else in the graphic where I already have data.  They will serve to build confidence that no new systematic variable (i.e., not random) has entered into my experimental operating procedures and will provide a couple of more runs to help randomize the eight runs just mentioned.  

I now want to turn my attention to the results from last night.  My apnea indices have never been lower.  See screen shots.  But there is no point in the night when the flow patterns approach anything that could be called normal.  Further, my Flow Limits are up (both 95% and Peak) and the two periods when pressure increased corresponds to periods of highest flow limits.  I'm really sleepy today.  I think this all screams I need more pressure support something the board moderators have been saying all along. 

           

This observation led me to go back to the Apnea Board Forum and do a "Search" on the key words "Flow Limits".  Doing so led me to a very recent thread by ctyankee titled "Need a primer on flow limits".  Sleeprider's response is fantastic.  It very much confirms my need for more pressure support to make the use of the EERS more successful.  The pressure support to lower flow limits while the EERS prevents the onset of CA's.  

I've been looking around the web for a used AirCurve 10 Vauto.  Is that the best equipment for my needs?  There are several other AirCurve models.  I want to make sure I'm getting the correct one if I make the investment as I doubt it will be returnable.  Any cautions regarding doing this will be appreciated.

Also, before doing this I want to better understand the consequences of increased TV, if any.  Note that my Median TV was up to 780 last night with 12 inches of EERS.  Normal (without EERS) is at or just below 600.  Is anyone aware of any potential, negative health consequences of increased TV?

If any of this is incoherent, keep in mind I am very sleepy today.  At least that is a good excuse  .

[slowriter]

I've been looking around the web for a used AirCurve 10 Vauto.  Is that the best equipment for my needs?

Yes.

Do note that people selling used Resmed devices often confuse the models; listing as, say, an autoset what is really a vauto, or vice versa.

PS - the post you link to is from Sleeprider; not me.

[sherwoga]

I've been looking around the web for a used AirCurve 10 Vauto.  Is that the best equipment for my needs?

Yes.

Do note that people selling used Resmed devices often confuse the models; listing as, say, an autoset what is really a vauto, or vice versa.

PS - the post you link to is from Sleeprider; not me.

I've corrected the link!  Sorry.

[slowriter]

If and when you manage to get ahold of a VAuto, to pick up where you left off, you'd set EPAP min to 5, and PS to 4.

This would be conceptually similar (if this existed) to min pressure of 9 and EPR of 4.