EERS Experiment Data (sherwoga)

[Gideon]

That is the conversion.

[Sleeprider]

Very interesting evolution of this research. Keep up the good work. (I edited my name for the thread you referred to).

[Geer1]

I tried reviewing this all but I see a ton of information and not a lot of data to be able to draw any conclusions off of. The OSCAR charts provided don't always show a correlation with changing EPR or EERS as one might expect they should. I know you have more data and have commented on some correlations so I imagine it just isn't clear because you haven't posted it.

Part of the problem imo is that you are playing with too many variables making it difficult/near impossible to draw clear conclusions from. Your goal is to figure out EERS but you are only keeping one thing consistent and that is starting EPAP (which changes immediately making most nights of data difficult to compare).

The goal of EERS is to try to limit central apneas while allowing greater PS. EPR should not be a variable, it should be set and it should be set at 3. EPAP is a variable as well and although EPAP and IPAP don't have as much effect on flow limitations as PS does they still do have effect and we see that consistently when comparing PR users to Resmed users. Machines that increase pressure to deal with flow limitations are effective at least in some people, I believe it all has to do with the type of flow limitation (whether it is caused by variable flow restrictions like tongue position etc or whether it is fixed due to nasal passage structures etc). We don't know what your cause of flow limitation is so pressure is still a variable and it should be taken out of the picture by switching to CPAP mode.

What I would do is set in CPAP mode, EPR of 3 and pressure of 12 (just based off quick review of a few charts but you might have better info on median/95% pressure ranges). Then I would try your different lengths of EERS out for multiple nights with each one and then review the resulting data to try and see how it affects you.

Some of the data I saw I didn't like, specifically with the longer EERS it looked like you were having more periods of high respiration rate. What is harder to tell is if that if that is because of the EERS or because of rem sleep. I believe your breathing gets even more ragged, higher respiration rate and higher flow limitations during rem sleep the same as mine does (even more so with yourself) so just having some nights with different sleep architecture could throw your data out (like I say way too many variables) hence importance of collecting numerous days of data then comparing median and 95% values for critical criteria.

Having limited these variables you would then be capable of visibly comparing the data by creating charts for each criteria. Chart for AHI, CAI, Tidal Volume, Minute Volume, Respiration Rate, maybe inspiration and expiration rates if there seems to be correlation on them. For AHI and CAI you need to make sure to remove sleep wake junk apneas (both central and obstructive) which is a little difficult, days where you know you were awake for a significant amount of time should be thrown out as they would influence all of the data too much. I would chart both median and 95% data (possible could put on same charts) to see how they are affected by EERS.

With that information you could then draw a conclusion on how the different length EERS affect your sleep and if they appear to be helping or not (I assume the response would be parabolic at least on some of these graphs and some might just show clear improvement or decline). Then you could pick an EERS length to use and do another similar test this time collecting data for EPR 2 (lower set pressure 1 to maintain EPAP) which will allow you to then compare the EPR 2 data to EPR 3 data to verify that breathing does improve with increased EPR/PS. 

I personally am not sold on EERS yet, probably because I haven't seen a good example of it working yet and although it does improve tidal volume I am not sure if the method it does so is ideal. I think I would personally shell out the money for an ASV rather than a Vauto and then at least I would know the machine is going to treat my breathing rather then potentially making it worse and never finding an EERS solution that works.

[slowriter]

The cost of ASV is much higher, and so accessibility much lower, than CPAP or bilevel.

If EERS can be shown to make the latter two viable for people like the OP, that's a great reason to give it a try.

It's in theory, a cheap, simple, and elegant solution.

[Geer1]

When you read the studies they use an inline CO2 sensor to determine proper EERS size and operation.

That is one of the big differences and why this isn't as simple as one might hope. CO2 levels depend on the person and you are trying to walk a tight rope to maintain the ideal CO2 level without going to far (otherwise you would cause arousals among other issues).

One thing that really caught my eye was how PLM was affected by EERS. In following study PLM index decreased from 6.1 to 2 going from untreated to normal CPAP and then increased to 15.1 after EERS. AHI was resolved and RDI significantly improved but was still high (probably due to higher CO2 levels). I think most on here would agree RDI of 30 is still pretty bad.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3014237/

In this study next step from EERS was ASV (shown in figure 1)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3998090/

Although it is cheap I don't feel it is as simple as one might think and it doesn't appear to work for everyone.

I still think you can learn more and potentially figure this out I just think you need to remove a bunch of variables in order to do so (or figure out a way to test CO2 levels and determine ideal EERS size that way).

Edit: One thing worth noting about EERS vs ASV is that ASV doesn't increase CO2, it just tries to force you to breath regardless of what your brain is telling you which as one of those studies mentioned can create issues. Makes sense and wasn't something I had really thought of before. Bother EERS and ASV have advantages and disadvantages.

Edit2: I was looking at your EERS build thread and was wondering if you took mask size into consideration? 6 inches of tubing at 60 ml each plus mask and swivel means your 18 inch is probably too large pased on the 100-150 ml mentioned in studies.

[Gideon]

If you look at this experiment, EPAP, managing OA, is a constant 5. The variables are PS (EPR) of 0,1,2,3 and EERS of 0,6,12,16

The effectiveness of EERS is more dependent on the source of the Centrals. If they are caused by CO2 levels dropping below the apneic threshold then EERS IS a viable solution. From other causes EERS will be ineffective.

[Geer1]

If you look at this experiment, EPAP, managing OA, is a constant 5.  The variables are PS (EPR) of 0,1,2,3 and EERS of 0,6,12,16

The effectiveness of EERS is more dependent on the source of the Centrals.  If they are caused by CO2 levels dropping below the apneic threshold then EERS IS a viable solution.  From other causes EERS will be ineffective.

EPAP is only constant at the beginning of the night then APAP takes over and adds another variable. The desire is to increase EPR/PS to deal with flow limitations without inducing centrals and it has already been determined EPR of 3 is required for flow limitations so I see no point in using EPR as a variable. 

Just my thoughts as I don't see any definitive conclusions from this test and Sherwoga has drawn little to no conclusions either. If you want to draw conclusions and figure out proper EERS size you need to start getting rid of variables or test for CO2 levels.

Edit: To go another step further regarding the EPR discussion. Change in tidal volume with adjustments to EPR/PS is minor and such the amount of CO2 to air is not going to make a significant change so EERS size should not have to vary significantly at different levels of EPR/PS. If you figure out ideal EERS size at say EPR of 2 and then want to adjust EERS for PS of 4 then just determine the %change in tidal volume and increase your EERS by that factor to keep CO2% the same. Because of minimal effect EPR should be removed as a variable, then as per my original post you can test it and see if there is any significant difference although the effect of changing EPR is likely far more significant then that of EPR's effects on EERS so I question what the numbers would really tell you.

[Gideon]

The other factor that enters into this is time. Treatment-Emergent Central Apnea is known to frequently disipate with time, 2 to 3 months.
I also agree that the results here are marginal, but we started with fairly low levels of Central Apnea. I do see a decrease in Central Apnea with an increase in EERS.

I do see this as a potential alternate to ASV for individuals that show a persistent high CO2 based Central apnea. I view ASV as treating the symptom of not breathing and EERS as treating a cause, CO2 levels dropping below the apneic threshold for the individual.

[sherwoga]

Geer1 wrote yesterday what I've manually inserted below using copy and paste.  I'm inserting my responses in bold in the quote.  I'm sorry I didn't answer more quickly.

RE: EERS Experiment Data (sherwoga)

I tried reviewing this all but I see a ton of information and not a lot of data to be able to draw any conclusions off of. The OSCAR charts provided don't always show a correlation with changing EPR or EERS as one might expect they should. I know you have more data and have commented on some correlations so I imagine it just isn't clear because you haven't posted it. I purposely have avoided posting a lot of my effort/results and may comment later as to why.  For now, the effort you've made to understand and comment is appreciated.

Part of the problem imo is that you are playing with too many variables making it difficult/near impossible to draw clear conclusions from. Your goal is to figure out EERS but you are only keeping one thing consistent and that is starting EPAP (which changes immediately making most nights of data difficult to compare). I purposely approached this project avoiding what some call the OFAT (one factor at a time) experimental approach.  Such experimentation is how I was trained in college and graduate school to do research and was the bread and butter of much of science career.  It wasn't until roughly half way through my career that I became aware of the power of using multiple factor experiments to conduct research.  This is not the correct venue to try and define/defend doing so for this research.  Instead, I refer you to this link for some justification. This is a sub page of a "Quality Portal" where there is a good discussion of "Design of Experiments".  For a much broader take on related concepts use the "Home" link in the upper right hand corner.  Each sub page found there gives relatively brief discussions of the concepts involved.  

The goal of EERS is to try to limit central apneas while allowing greater PS. EPR should not be a variable, it should be set and it should be set at 3. Before I was even introduced to the EERS and after my very first post to this board which included a very early screenshot of my sleep performance (from OSCAR), Bonjour recommended I drop my EPR from 3 to 1.  My centrals were reduced dramatically, but the flow limitations then became apparent.  The next phase of guidance I got from the board was to consider the EERS.  The story evolves from there, but for now it was logical to consider EPR as a factor in the multiple factor experiment because of this observation. EPAP is a variable as well and although EPAP and IPAP don't have as much effect on flow limitations as PS does they still do have effect and we see that consistently when comparing PR users to Resmed users. Again I had guidance from the board to maintain the minimum EPAP constant.  I didn't understand it at the time and still don't fully understand it, but have come to be suspicious that it might have been better to have included minimum EPAP as a third factor instead of holding it constant.  Doing so would have required more effort as the amount of effort goes up significantly in a Designed Experiment with the number of factors included.  But understanding some of the effects you allude to might have made it worth it.  Again I appreciate your interest and effort, but we look at experimentation very, very differently.  Machines that increase pressure to deal with flow limitations are effective at least in some people(I hope so), I believe it all has to do with the type of flow limitation (whether it is caused by variable flow restrictions like tongue position etc or whether it is fixed due to nasal passage structures etc)(unknown). We don't know what your cause of flow limitation is so pressure is still a variable and it should be taken out of the picture by switching to CPAP mode.  Or it should be investigated and proven to be or not to be a controlling influence by adding it as a third factor to the design.  Just saying (don't actually plan on doing it at this point as I am committed to getting the Vauto).

What I would do is set in CPAP mode, EPR of 3 and pressure of 12 (just based off quick review of a few charts but you might have better info on median/95% pressure ranges). Then I would try your different lengths of EERS out for multiple nights with each one and then review the resulting data to try and see how it affects you. See my comments above.  I'm pretty averse to OFATs having seen during the last half of my working career the power of multiple factor experimentation resulting in savings of hundreds of thousands of dollars in production processes that were at least as complex as breathing.  There are simple techniques to extract the information from DOEs (Design of Experimentation).  But again this is not the venue where I would try to explain them, nor are my writing skills good enough to do the subject justice.

Some of the data I saw I didn't like, specifically with the longer EERS it looked like you were having more periods of high respiration rate. I observed the high respiration rate early in my effort and asked about it.  Bonjour replied with what at the time seemed like a terse comment, but in hindsight turned out to be a very concise, spot on answer to my question.  I admire his brevity.  OSCAR increments the respiration count by one every time the flow signal crosses the zero line.  My flow limitations and flow patterns result in a major adulteration of this measurement (of respiration rate) technique making the respiration rate output essentially meaningless, at least in periods of very high apparent respiration rate.  When you stop and think about it a respiration rate of 50 is pretty dog gone fast.  I can't imagine myself staying asleep at all if I was panting that fast.   

   

This plot is from last night.  I did NOT use the EERS.  EPR was 2 and Min Pressure 7 for an initial EPAP of 5.  The flow pattern and adulterated respiration rate was observed for about 30 minutes.  But my flow pattern is never ideal.  It is always flat topped or starts decreasing long before the mask pressure (due to EPR) reaches it's maximum.  

What is harder to tell is if that if that is because of the EERS or because of rem sleep. I believe your breathing gets even more ragged, higher respiration rate and higher flow limitations during rem sleep the same as mine does (even more so with yourself) so just having some nights with different sleep architecture could throw your data out (like I say way too many variables) hence importance of collecting numerous days of data then comparing median and 95% values for critical criteria. Your comments about REM sleep are of great interest to me.  At this point I don't know if one can or how to identify REM sleep from the OSCAR data.  Further, understanding the different stages of sleep would be a great improvement for me.  Perhaps more dialog on this will ensue in the future.  I certainly am interested.   

Having limited these variables you would then be capable of visibly comparing the data by creating charts for each criteria. Chart for AHI, CAI, Tidal Volume, Minute Volume, Respiration Rate, maybe inspiration and expiration rates if there seems to be correlation on them. For AHI and CAI you need to make sure to remove sleep wake junk apneas (both central and obstructive) which is a little difficult, days where you know you were awake for a significant amount of time should be thrown out as they would influence all of the data too much. I would chart both median and 95% data (possible could put on same charts) to see how they are affected by EERS. I hope to share some of my results from my data analysis of my experiment as it is.  I am committed to writing a WIKI article, but remain in a state of flux as to what that will look like and as to how much actual statistical data analysis to include.  Graphs would certainly tell the story the best way, but they will not look like graphs from an OFAT.  

With that information you could then draw a conclusion on how the different length EERS affect your sleep and if they appear to be helping or not (I assume the response would be parabolic at least on some of these graphs and some might just show clear improvement or decline). I already know that I can eliminate C and O apneas (to a nightly AHI of < 2) using 2 units of EERS (~ 116 cc or something just a bit more than that) with an EPR of 3 and min pressure of 8.  This treatment combination was not part of the original design, but the analysis of the outputs of that design (not shared fully) led me to try this combination.  Flow patterns are still horrible.  I look forward to getting the Vauto to try to increase the PS to see if doing so addresses those flow patterns and attendant flow limitations.  And if I see improvement, I might have to again visit the size of the EERS.  Then you could pick an EERS length to use and do another similar test this time collecting data for EPR 2 (lower set pressure 1 to maintain EPAP) which will allow you to then compare the EPR 2 data to EPR 3 data to verify that breathing does improve with increased EPR/PS. 

I personally am not sold on EERS yet Me neither, probably because I haven't seen a good example of it working yet I would appreciate your good will, prayers and wishes, that my case might be the first and although it does improve tidal volume I am not sure if the method it does so is ideal. I think I would personally shell out the money for an ASV rather than a Vauto and then at least I would know the machine is going to treat my breathing rather then potentially making it worse and never finding an EERS solution that works.  Note my earlier comments.  The ASV is not a current option as I've already made the verbal commitment to purchase the Vauto.  That should actually become a purchase later today, one I feel obligated at this point to make as my contact has already ordered it on my behalf.  

You use the word "improve" with reference to tidal volume.  The single biggest, most statistically significant effect I see in my data is with regard to TV.  I've seen a lot of discussion of EERS and TV, but I've not noticed anyone saying that increased TV is good or bad.  With no EERS my TV runs from about 540 to just under 600, which I think is normal.  It goes up with each increase in EERS length.  Could you expand on your observation?

[sherwoga]

When you read the studies they use an inline CO2 sensor to determine proper EERS size and operation.

...

Edit2: I was looking at your EERS build thread and was wondering if you took mask size into consideration? 6 inches of tubing at 60 ml each plus mask and swivel means your 18 inch is probably too large pased on the 100-150 ml mentioned in studies.

I've already seen at least some of the studies you provide links to.  I'll check them out again to see if there is one or more I haven't seen.  But I'm either missing your point entirely or doesn't seem to have much merit since I'm not likely to acquire the needed equipment.  Here I want to reply to your consideration of the EERS volume and to comment that I like the way you think.  I am an analytical chemist and rooting out sources of systematic error is near and dear to my heart.  

I fully recognize that both the swivel valve and an increased part of the elbow-Hose to Mask-adapter increases the total amount of un swept (or dead) volume in the EERS.  I've thought about ways I could measure it by weighing the amount of water it takes to fill the EERS.  I haven't actually acted on that.  I'm not sure I really need to and believe that the random variation operational in this entire system probably swamps any small impact from this systematic error.  As it stands in it's uncorrected state, it would be one reason for curvature that might be observed in the outputs, but again the statistics just aren't that good.