Please Help Me Interpret my Stats

[MJS_]

Last night was my best sleep so far using (auto) CPAP. Since my machine won't tell me when I was sleeping , I made a point of turning my machine off and back on to mark those periods when I did not fall asleep and wanted to pause the therapy to adjust my headgear or humidity setting. I also turned the machine off and on when I woke up due to mask discomfort/noise or to urinate due to BPH. When I loaded last night's data into OSCAR, I was able to see that my AHI during the two sessions in which I never slept was 2.14 For the four sessions in which I slept (totaling 5 hrs 52 minutes which probably included close to 5-1/2 hrs of sleep), my AHI was 0.17 caused by a total of 1 Hypopnea event and 2 RERA events. My ResMed "mask seal" score was 20/20 and OSCAR reports a median Leak Rate of 0.00 with no Large Leak events for the sessions in which I slept (there were a few large leak events in the two sessions in which I did not sleep).

I've been inching my Min pressure setting up and my Max pressure setting down to find an optimal narrow range. My settings last night were 5.6 to 7.8 cmH20 with a 15 minute Ramp at 5 cmH20. OCAR reports my Median Pressure statistic was 7.78 for the total of my four sleep sessions, and also 7.78 for the session in which zero "Events" were detected. Why might my AirSense 11 want to deliver close to the max pressure nearly all the time?

I am not familiar with RERA events; could they be caused by my brain rather than my tongue? Could they be false positive flags caused by having to wake up to urinate or due to discomfort?

Any pressure setting recommendations based on this data? [I'm not yet capable of extracting more detailed information from OSCAR.]


EDITED: I realize I misinterpreted the 95% and 99.5% pressure stats so I edited my post to report the median pressure.

[Miss Emerita]

It would be helpful if you would post a screenshot of your Oscar chart. You will probably need to use an image-hosting service like Imgur, because the attachment capacity of this site is very limited.

[MJS_]

It would be helpful if you would post a screenshot of your Oscar chart. You will probably need to use an image-hosting service like Imgur, because the attachment capacity of this site is very limited.

I see that OSCAR has 14 charts. Do people post screenshots of all of them? Is there a tutorial link for how to do this?

EDIT: Nevermind.... I found the OSCAR screenshot command.

[MJS_]

Here is the link to my OSCAR screenshot. I removed (unchecked) the two sessions during which I did not sleep.

https://imgur.com/a/Egc2STp

[Miss Emerita]

Thanks. Could you make some changes and repost? The key graphs are these:

Events
Flow rate
Pressure
Leaks
Snores
Flow limitations.

Move the graphs around so that all and only these graphs show in your screenshot. You can fit them in by grabbing the grey bars that separate them and pushing them up a little.

[MJS_]

Here's my screenshot of those OSCAR graphs:

https://imgur.com/a/xQIE80I

Is that helpful? I don't really know how to scroll through the timeline of the graphs.

[robysue1]

Here is the link to my OSCAR screenshot. I removed (unchecked) the two sessions during which I did not sleep.

https://imgur.com/a/Egc2STp

First, can you make a screenshot that actually shows the flow rate graph, the pressure graph, and the leak graph. And the flow limitation graph if you can without reducing the sizes of the graphs to the point where they are difficult to read. The shot that you posted has none of those necessary graphs to answer the questions in your original post.

Second, since you are talking about AHI in the sessions when you were asleep and when you were not asleep, it's worth either posting the whole night's data (and telling us which sessions were the ones you never fell asleep), or posting a second shot where those are the sessions that are "on" and the others are off.


That said, I do want to respond to this in your original post:

I've been inching my Min pressure setting up and my Max pressure setting down to find an optimal narrow range. My settings last night were 5.6 to 7.8 cmH20 with a 15 minute Ramp at 5 cmH20. OCAR reports my Median Pressure statistic was 7.78 for the total of my four sleep sessions, and also 7.78 for the session in which zero "Events" were detected. Why might my AirSense 11 want to deliver close to the max pressure nearly all the time?

Given the low AHI, the most likely reason your machine is running close to max pressure for 50% (or more) of the night is flow limitations, snoring, or a combination of both. But in order to really tell why the machine is hitting max pressure so often, we need to see the flow rate graph, the pressure graph, the flow limitation graph, and the snore graph.

You also write:

Last night was my best sleep so far using (auto) CPAP. Since my machine won't tell me when I was sleeping , I made a point of turning my machine off and back on to mark those periods when I did not fall asleep and wanted to pause the therapy to adjust my headgear or humidity setting. I also turned the machine off and on when I woke up due to mask discomfort/noise or to urinate due to BPH. When I loaded last night's data into OSCAR, I was able to see that my AHI during the two sessions in which I never slept was 2.14

Looking at that known-to-be wake data would be useful to you:

First, you will be able to get a sense of what your particular wake breathing looks like. You will also be able to learn why your AirSense 11 responded (or didn't respond) to the events that were flagged as OAs, Hs, or CAs even though you know you were awake. In other words, it will help you understand why we tell newbies that PAP machines doesn't "know" (for sure) when you are sleep.

Second, looking at that data along with data from when you were sure you were asleep will help you understand that your AirSense can only detect that there is what appears to be a breathing human being at the end of the mask and it can track the flow rate into and out of that alleged breathing human being's lungs with some precision. As such, the machine's programming can make intelligent guesses about whether the alleged breathing human being is asleep and experiencing sleep disordered breathing events and respond to them. If your AirSense 11 is running during an AutoRamp period, you will also be able to see if/when the AirSense 11 terminated the ramp, and armed with that knowledge you can figure out which of the criteria the machine used to make an intelligent guess that you had probably fallen asleep.

I am not familiar with RERA events; could they be caused by my brain rather than my tongue? Could they be false positive flags caused by having to wake up to urinate or due to discomfort?

Machine detected RERAs are informed, intelligent guesses that a real RERA may have occurred.

Here's what you need to know about real RERAs as well as how an AirSense 11 is programmed to "flag" something as a RERA.

RERA stands for respiratory effort related arousal. On an in-lab PSG, determining when a real RERA has occurred requires the EEG data (to determine a real arousal has happened) and measurements of respiratory effort. In a sleep lab that wants to accurately measure RERAs, a PES device has to be added to the usual accoutrement of sensors. For a RERA to be scored, the PES data must indicate that respiratory effort is increasing during a series of breaths that are immediately followed by an EEG arousal and then a return to sleep with better sleep breathing. Respiratory effort indicates that the airway is compromised---i.e. it is in the very initial stages of collapse, but the collapse has not yet gotten bad enough to restrict airflow into the lungs enough for an H to be scored.

It's important to note three things:

1) If there's no EEG arousal, a RERA can't be scored even if the PES data indicates increasing respiratory effort is occurring.

2) If there is an EEG arousal, but the PES data does not indicate that breaths preceding the arousal show increasing respiratory effort, then a RERA can't be scored. (The arousal would likely be labeled as a spontaneous arousal in the data---meaning the arousal was real, but it was unrelated to sleep disordered breathing.)

3) If the PES data indicates that the respiratory effort is increasing a series of breaths that occurs in WAKE, then a RERA is not scored: RERAs are part of sleep disordered breathing, so for the event to be real, the subject has to be asleep.

Now, our PAP machines don't have the EEG data and they don't have the PES data needed to score a real RERA. What the engineers and programmers for the AirSense 11 have done is a lot of statistical study of real flow rate data from real PSGs conducted with PES. They've analyzed the characteristics of the inhalations in the flow rate data that are strongly correlated to the real RERAs scored on real sleep tests. And they've used that analysis to program the machine's RERA detection algorithm. It's looking for a series of inhalations with the earmarks indicating probable increasing respiratory effort followed by one or more so-called recovery breaths, which have the earmarks of the breaths during the EEG arousal on real RERAs scored on real PSGs using PES.

How good is the AirSense 11 RERA algorithm? I haven't the foggiest idea. PR has had a RERA algorithm going back to the original System Ones (which date from circa 2010). Resmed didn't introduce a RERA algorithm until the "S9 AutoSet For Her" was introduced. And the RERA algorithm was not part of the standard Auto algorithms event detection on S9 AutoSets and AirSense 10 AutoSets. As I recall, S9 For Hers and AirSense 10 For Hers would only flag RERAs if the "Auto For Her" mode was selected. With the introduction of the AirSense 11 machines, the "For Her" versions went away and the "Auto For Her" algorithm was simply incorporated into all AirSense 11 AutoSet as a second "auto mode" in the clinical menu. I don't know whether the AirSense 11s only record RERAs if the machine is running in Auto for Her mode or if it is running in any of Auto, Auto for Her, or CPAP modes.

The upshot of all this in connection to your questions is this:

"could they be caused by my brain rather than my tongue?" On a real PSG, RERAs involve an unstable upper airway. That means they're not caused by just your brain---i.e. they are not "central" events where your brain is just forgetting to breath (or forgetting to breath deeply enough). Whether the tongue or upper palate or uvula or something else in upper airway is causing the increasing respiratory effort can be difficult to tease out.

"Could they be false positive flags"? Of course they can be false flags: If you were awake when a RERA is scored by the AirSense 11, then that event is not a real sleep disordered breathing event simply because you were NOT asleep. They could also be false flags because the machine is misidentifying an inhalation pattern that is correlated to (but not necessarily caused by) increasing respiratory effort. Or a false RERA could be scored by the AirSense 11 picking up "recovery breaths" that are associated with a spontaneous arousal that is not related to increased respiratory effort. The point is, however, that Resmed's engineers and programmers believe that most of the time when a real RERA occurs, the machine will score a RERA. (i.e. there aren't too many "missed" RERAs) and that the number of false RERAs scored by the AirSense 11 is not so high that it will distort trending data looked at over weeks and months rather than looking at each individual RERA on a particular night's data.


"Could they be false positive flags caused by having to wake up to urinate or due to discomfort?" You'd have to have a decent sense of what your individual wake breathing typically looks like. In general, the breathing just before we are consciously aware that we are awake is often a transitional type of breathing pattern that is different from real sleep breathing. If your particular pattern of breathing while transitioning to wake has characteristics that match the machine's criteria for scoring a RERA, then yes, some machine scored RERAs could be caused by the fact that you woke up to urinate or you woke up in some kind of discomfort. But if a real RERA occurred right before a wake, it's also possible that the EEG arousal associated the RERA turned into a real WAKE---i.e. an EEG stage that is NOT sleep and lasts long enough for you to become consciously aware of the fact that you are indeed awake rather than asleep. And once you were consciously awake, you then noticed the full bladder or what ever other kind of discomfort you thought was responsible for the wake.

Teasing out whether a machine scored RERA right before a wake is real or a false positive is guess work: We just don't have the EEG data to determine whether you were already awake when that RERA was scored (so it's a false positive) or whether you were asleep when the RERA occurred, but the arousal itself was not transitory but led to you coming to a full wake.

Any pressure setting recommendations based on this data?

Without seeing the flow rate graph, the pressure graph, the flow limitation graph, and the snore graph all at the same time, none of us can do more than make a wild-ass guess about what to do in terms of your pressure settings.

[robysue1]

Here's my screenshot of those OSCAR graphs:

https://imgur.com/a/xQIE80I

Is that helpful? I don't really know how to scroll through the timeline of the graphs.

Much better.

If you copy the BBCode stuff on imgur and paste it into your post, the image will show up in your post. Here's what that data looks like:



This screen shot definitively shows the following:

Your AirSense 11 is hugging your max pressure of 7.8 for most of the time you were sleeping with the machine because the machine is detecting a lot of residual flow limitations. And it wants to increase the pressure further in an effort to smooth out the shape of the inhalations and eliminate the flow limitations.

You can think of a flow limitation as an early warning that the airway is in danger of collapsing: As the upper airway becomes unstable, the shape of the inhalations is distorted and the AirSense 11 can pick that up (and flag it in the Flow Limitation graph). Because flow limitations indicate the airway is in danger of collapsing, the Auto algorithm is designed to increase the pressure to prevent further collapse and further destabilization of the airway: The machine wants to proactively increase the pressure to prevent Hs and OAs from being able to occur.

Given this data, I think you need to increase both your min and max pressures. It looks to me like you most likely need a minimum pressure that is around 7.0-8.0cm. And unless aerophagia is an issue, I think this is one case where increasing max pressure to something like 10-12cm would allow the machine to treat those remaining flow limitations.

If more pressure doesn't eliminate the flow limitations and/or creates problems with aerophagia, then that's the time to revisit what narrow pressure range would be appropriate.

Whether the two RERAs scored are real or not cannot be determined from this screenshot. You'd have to zoom in to a window that shows no more than 3-5 minutes worth of breathing for each RERA, and you might need to be zoomed in even closer and then scroll through what was happening both before the RERA and after the RERA. Even then, you'd still be guessing, but at least it would be able to make an intelligent guess backed up by reasons shown in the data.

Same thing with that H: At this level, it's hard to tell if it occurred during sleep or if there's some SWJ and this is just part of transition to wake breathing that got mis-flagged because the machine doesn't know you're in the process of waking up.

[MJS_]

Thanks so much for your feedback! I find it helpful to know that RERA events are not considered central apnea.

[snip]

Second, since you are talking about AHI in the sessions when you were asleep and when you were not asleep, it's worth either posting the whole night's data (and telling us which sessions were the ones you never fell asleep), or posting a second shot where those are the sessions that are "on" and the others are off.

[snip]

In regard to my therapy data while awake, what I know is that my breathing has NOT been typical of how I normally breath when attempting to fall asleep due to my struggles adapting to the equipment. Also, the nature of my wake breathing has varied based on my changing pressure and comfort settings, as well as my recent swtich from F&P's uncontrollable excessively heated air hose to ResMed's controllable air hose and my recent switch from a poorly fitted face mask to a better fitting one. Today, a different style of full face mask (recommended by a sleep technician) arrived at my door (shipped by my DME) and I'll be trying that one out next. So I suspect my awake breathing data may be more useful when my CPAP therapy is more stable and better tolerated.

[MJS_]

Your AirSense 11 is hugging your max pressure of 7.8 for most of the time you were sleeping with the machine because the machine is detecting a lot of residual flow limitations. And it wants to increase the pressure further in an effort to smooth out the shape of the inhalations and eliminate the flow limitations.

You can think of a flow limitation as an early warning that the airway is in danger of collapsing: As the upper airway becomes unstable, the shape of the inhalations is distorted and the AirSense 11 can pick that up (and flag it in the Flow Limitation graph). Because flow limitations indicate the airway is in danger of collapsing, the Auto algorithm is designed to increase the pressure to prevent further collapse and further destabilization of the airway: The machine wants to proactively increase the pressure to prevent Hs and OAs from being able to occur.

Given this data, I think you need to increase both your min and max pressures. It looks to me like you most likely need a minimum pressure that is around 7.0-8.0cm. And unless aerophagia is an issue, I think this is one case where increasing max pressure to something like 10-12cm would allow the machine to treat those remaining flow limitations.

Thanks again! I suppose it makes sense that I'm having "flow limitations" since my (perhaps ill-advised) goal has been to approach the minimum air pressure needed to prevent OAs. If Hs and OAs are not occurring, then is it common or widely accepted knowledge (among apnea experts) that the air pressure should be increased to eliminate flow limitations? How harmful are air flow limitations in the absence of Hs and OAs?

What is the normal range for the Flow Limitation summary statistics (median, 95%, 99.5%)?

[palerider]

How harmful are air flow limitations in the absence of Hs and OAs?

What is the normal range for the Flow Limitation summary statistics (median, 95%, 99.5%)?

Get a drinking straw, breathe through it for a few minutes.

That's a flow limitation, let us know what you feel after doing that.

[MJS_]

How harmful are air flow limitations in the absence of Hs and OAs?

What is the normal range for the Flow Limitation summary statistics (median, 95%, 99.5%)?

Get a drinking straw, breathe through it for a few minutes.

That's a flow limitation, let us know what you feel after doing that.

Useful analogy! I'd still like to learn how far (or how many SD's for those who are math professors ) my Flow Limitation statistics are from the average, but I suppose I'll start inching my Min/Max air pressures up now.

[palerider]

I'd still like to learn how far (or how many SD's for those who are math professors ) my Flow Limitation statistics are from the average,

Which does you absolutely nothing to help you optimize your therapy.

You need what YOU need, it has nothing to do with what *I* need, or Pugsy needs, or a certain excellent math professor needs to make our sleep as good as possible.

[MJS_]

I'd still like to learn how far (or how many SD's for those who are math professors ) my Flow Limitation statistics are from the average,

Which does you absolutely nothing to help you optimize your therapy.

A couple points.... Diagnostic tests in the fields of psychology and medicine (including sleep disorders) generally rely on the concept of how much an individual's results vary from the mean, median, or "normal" range. Also, pretty much any medical or physical intervention that alters how our bodies function has the potential for negative side effects. It is possible that increasing CPAP air pressure until all flow limitations are eliminated could have negative side effects that outweigh the benefits.

You need what YOU need....

Since I am too early in my CPAP journey to know what I need, knowing how far my results deviate from what is normal may help me make informed decisions.

[palerider]

Since I am too early in my CPAP journey to know I need, knowing how far my results deviate from what is normal may help me make informed decisions.

I don't understand how.

Then again, I don't *need* to understand how you think it's going to help you.