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Apnea statistics question, how tightly controlled is your apnea?
#11
RE: Apnea statistics question, how tightly controlled is your apnea?
@sheepless My goodness, didn't realize what a mine field that thread would be.  I read through most of it, and still don't understand the method fully.  It seems it helped some people, so that's good.  The recipe never was succinctly stated, but I have a vague sense of it.  Not sure I could reproduce it though.

For the moment, let's not intertwine the threads.  There's merit in scatter plots, but I have to think about things more.

At some level, I prefer to think of this as a multivariate optimization problem.  Whether that's an accurate assessment or not, I don't know yet.
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#12
RE: Apnea statistics question, how tightly controlled is your apnea?
this is way out of my element so one final post. I understand the value and necessity of an exploratory discussion. maybe it's just me but at that level it's just too big and vague to get my head around. you know, lots of variables, all interacting, some in known ways, some interactions ill defined or just not understood. not to mention variability among individuals. I was just thinking that an additional approach at some point along the way would be to pick something, a goal that you want to use numbers and analytic tools to evaluate, then test your hypotheses about to get there or expected responses or whatever. maybe that's similar to your minimization (?). my thought is it would be like gaining an understanding of a tree, then the relationship among trees, underbrush, over-story, animals, soil, climate, whatever, how each influences another, to build an understanding of the whole forest ecosystem. I just don't know of another way to understand a system without understanding relationships among key elements. as that becomes clearer, it might also become clearer how to manipulate variables to achieve a desired outcome. seems to me these are the kind of fundamental questions you're posing, like which elements, which elements in relation to specific other elements, how to measure them, their relative importance with respect to achieving the goal, how to should they be weighted, etc. a problem I foresee is how to account for factors external to pap machines, like physical variability among individuals, certain health conditions, sleep hygiene factors, tolerance levels like for high or variable pressure, leaks and so on.

experienced members already use the stats generated by the machines and reported by oscar, their understanding of how certain factors operate and influence each other, and how altering them may produce certain outcomes. so maybe a starting point would be to hone in on what specifically is the value you want to add.

good thing this is an exploratory discussion, because I'm winging it, putting off today's mundane household projects.
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#13
RE: Apnea statistics question, how tightly controlled is your apnea?
"experienced members already use the stats generated by the machines and reported by oscar, their understanding of how certain factors operate and influence each other, and how altering them may produce certain outcomes. so maybe a starting point would be to hone in on what specifically is the value you want to add."

This is what I'd like to help out with.  What I'm attempting to explore (and by your comments, I haven't made myself clear enough) is to try to somehow come up with "what you just said" and add these sorts of tools.

My apologies to you, no intent to go for pie in the sky.  Sorry if it was too abstract.  I'd simply like to somehow encapsulate some of above, so it's more available to our users.  So more or less, how do our experienced staff do this?  They are using metrics to make decisions on what to do next.  Can this be described more?  Believe me, this isn't an attempt to automate our ways out of a job.  It's more of an augmentation, so we can help more people.

This seems to be migrating towards feature talk, maybe it should be moved?  Or keep it here?
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#14
RE: Apnea statistics question, how tightly controlled is your apnea?
Look at titration principles, what do they try to accomplish.  The goal of titration is ultimately to "Optimize" therapy settings.  
Do note that most labs just look at which settings produced the best results in a very narrow window of time and call for those settings.

  1. EPAP eliminates OA, increase EPAP to eliminate OA, yes even on CPAP
  2. Increase PS/IPAP/EPR, leaving EPAP as determined in step 1, to eliminate H, FL, RERA

For CA in the "lucky" people, this is just for CPAP/APAP/BiLevel without other complicating issues
  1. Increased PS typically increases CA so Lower PS/EPR to decrease CA events
  2. Higher Pressures tend to increase CA so Lower Pressure (EPAP) to reduce CA events
  3. Pressure variability tends to increase PA so lower PS/EPR/Flex to reduce variability and thus reduce CA events
  4. Narrow the pressure band limits (Min/max pressure, Diff between min EPAP/Max IPAP) to approach a single pressure therapy, approach CPAP therapy wo EPR/PS/Flex
With CA present, always look for a balance between OA and CA.  This frequently is the point of lowest AHI but as CA goes down OA goes up.  The actions to reduce obstructive events tend to increase central events and vice versa.
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#15
RE: Apnea statistics question, how tightly controlled is your apnea?
Thanks @Gideon, this is helpful to have this succinct titration approach all in one spot.  I'm sure it will help myself and others to be able to make improvements in their therapy.  Certainly has given me some ideas to try.

Whether statistics are to be trusted or not, well I'm going to leave that.  All I know is I don't have any other better tools at my disposal.  There are entire disciplines which are based on them, so at some level stats can be of great use.  My data is so noisy, it's difficult to ascertain if my attempts at titration are indeed helpful.  That's why I have resorted to statistics and data smoothing techniques.  I've made some progress, so it seems like the approach has some merit.  However, it's a slow process.  Personally, I'd like to reduce the standard deviation of individual apnea types, as they lead to wild variations on how I feel.

My pet peeve with laboratory sleep studies is related to this.  One night, even in a lab, under relative control, is not indicative (in my opinion) of how one will do with a prescription PAP setting.  Humans seem to be too variable, both in their nature, habits and environments for a single night titration to be effective.  I'd like to get an idea how well individuals apneas are controlled using PAP machines.

If you consider your apnea under control, what are your statistics?  

What would be helpful is machine type and brand, #days at a unique setting, and stats for mean and stdev for CAI, OAI, HI.  If you track UAI and UF2I, please post them as well.  (If you do look at UF2's or UF1's, kindly note how you have defined them)  By a unique setting I mean, there have been absolutely no changes made to the machine for the test.  No changes in EPR, Ti, pressures, etc.  Just put on "mask" and go to sleep.

What is of interest to me are the relative comparison of means with standard deviations, and even the distributions of the apnea types.  Are they normal, Rayleigh, uniform like?  Are they indicative of tight control, or more haphazard?

If you have long spans (large number of days) at a unique setting, that's what I'd like to see.  If you fiddle with your settings everyday, that kind of data isn't helpful at the moment.  At the moment, I don't have long spans of data, I only have a 35 day span and a 20 day span that are readily available.  I suppose I could extract a very long span that I had on a previous machine, but this would only result in a data point set for one individual.

Sorry to be fishing around like this, but I don't know where else to ask this sort of thing.  Not going to find this info at my doctor's office, and probably not even PubMed.  (Just looked, but search there is pretty hard.)  Certainly not expecting anyone to go out and compute this stuff just for my curiosity, but if you are a data geek anyways and have this kind of info, I'd like to see it.
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#16
RE: Apnea statistics question, how tightly controlled is your apnea?
You said

Quote:My pet peeve with laboratory sleep studies is related to this.  One night, even in a lab, under relative control, is not indicative (in my opinion) of how one will do with a prescription PAP setting.  Humans seem to be too variable, both in their nature, habits and environments for a single night titration to be effective.  I'd like to get an idea how well individuals apneas are controlled using PAP machines.

Agreed, especially since the actual window of data that the Rx is defined from is frequently only minutes, not hours out of the night.  It is uncommon to find that the initial setting are working well for the user.  The main outcome of the Titration sleep study is that an Rx is written and a machine is purchased.  That is where we at the AB typically pick up and help the user.  

the number 1 criteria for success is subjective.  How does the user feel?
Before we get there we like to see a "success" by the numbers.
Criteria
  1. AHI < 5.0, which is accepted by the medical community.  This means a recognized event every 12 minutes on average, all night long.
  2. We here like to see about half that.
  3. chasing zero is futile.  
  4. A well-titrated user will have 
  • a fairly small pressure fluctuation (2 cmw)
  • A small Med FL (ResMed) of .10-.13 or less.  I'd like to see what stats say about this.  Higher values calling for increased PS/EPR.
  • Typically zero RERA events, because the flow limits are managed.
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#17
RE: Apnea statistics question, how tightly controlled is your apnea?
Very insightful.  

Have to agree with your comments on chasing zero.  Had a zero day once.  There was nothing magical about it.  Frankly, I've felt better on lots of non-zero days.  How you feel always is more important than numerical results.

Can you discuss further about median flow limitation?  Are you are discussing median flow limitation index?  At least for me, my index is low, because the majority of the time the limitation is zero, but have peak flow indices (during flow limitations) which are measurable.

One last question, on ResMed machines, do they detect RERA?  Since I have had a VAuto, I have not had a single RERA event flagged.  I would imagine there still are some, there's certainly a lot of micro-arousals (hallmark of UARS) still present in the data.  My Respironics had no problem flagging RERA's.  

The term RERA no longer seems to be in the Glossary.  In OSCAR > Preferences > Events it is defined as Respiratory Effort Related Arousal: A restriction in breathing that causes either an awakening or sleep disturbance.  According to SDB Workshop 2018 a RERA is a "Sequence of breaths lasting ≥ 10 seconds characterized by increasing respiratory effort or by flattening of the inspiratory portion of the flow signal leading to an arousal from sleep when the sequence of breaths do not meet criteria for an apnea or hypopnea".  

So is an event like this a RERA?  Or just a micro-arousal?  There was increased tidal volume in the interval between 23:48:46 and 23:49:30.
   
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#18
RE: Apnea statistics question, how tightly controlled is your apnea?
The image you posted is not RERA. I'll keep an eye out for a good image, but we would be looking for an increasingly flattened inspiratory wave leading to a higher flow rate indicating the arousal.

[Image: 4gm60ab.png]
Sleeprider
Apnea Board Moderator
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#19
RE: Apnea statistics question, how tightly controlled is your apnea?
Very interesting.  @Sleeprider It would be great if you could show a few more examples of RERA.  

Is RERA restricted to inspiry only?  Can one have increased collapse of expiry leading to a recovery breath?  Is that also RERA, or something else (nothing?)?  (Palatal prolapse?)
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#20
RE: Apnea statistics question, how tightly controlled is your apnea?
look here http://www.apneaboard.com/wiki/index.php...erapy#RERA

By Median I'm looking at the stats in the left sidebar for flow limits.  the .10 - .13 value was chosen by observation so if your statistical analysis can establish a more "justified" number let us know.  We know that hits in the flow limit chart are almost always accompanied by an increasing pressure on the ResMed.  SR, your take on the number?
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