A few questions a year or more into this

[Arlene1963]

After looking at SH charts for well over a year now I still have a few questions. I love looking at data, both mine and others, it's so interesting.

When I have obstructive events recorded they are usually preceded by an increase in flow rate and an increase in tidal volume. I find this odd as it seems it should be the opposite, i.e. large recovery breaths or arousals after the apnea not before.

Here is an example:



It almost looks the same as sleep wake junk.

Here is another example that is different to what I'd expect. Almost looks like a real central due to lack of change in flow rate and tidal volume before and after the event.



Jay posted a thread a while back with pics of SWJ but the pics are in Photobucket and they no longer display.

I know how to identify central "SWJ" and can rapidly ID the real deal, but not so much with obstructive events as they are still a bit of a mystery to me.

Do folks here think these examples are SWJ or legit obstructives? If they are obstructive in nature, why no recovery breathing after the events?

Thanks.

[Pugsy]

Sometimes it's really easy to identify asleep breathing events and awake breathing events/SWJ....and sometimes it isn't so easy for us lay people.

My opinion of the 2 you posted. The top one I lean towards SWJ because of the obvious arousal breathing right before the flag. If the arousal breathing had come after the flag instead of before I would lean towards real.
The bottom one I lean towards the real deal. Looks like asleep breathing right before and right after the flag.

[Arlene1963]

Thanks Pugsy! That's what I was thinking as well and because the second one is fairly short in duration no recovery breath would be necessary?

I usually have one or two of the second example per night recorded as centrals, so seeing it as an obstructive threw me a bit.

I always look at flow rate to figure out what is going on when my AHI nudges a bit higher. In my case it indicates restless sleep even though I am not aware of it, oddly. Last night of the 13 events recorded I think only 3 or 4 were the real deal.

[jnk...]

Although I don't read squigglies, I do believe that some of us may huff and puff a bit before we close off our airway, despite the PAP, with a sort of grunt, when we make a minor move to reposition ourselves slightly during sleep.

[CapnLoki]

I never paid much attention to the details of "Sleep Wake Junk" other than assuming it referred to either the period at the beginning of sleep where the body has trouble adjusting the breathing, or to the period of wakefulness following REM sleep. Given the regular breathing before and after the events, neither of these two examples look like those cases. What an I missing here?

[Pugsy]

I honestly don't know much about when a recovery breath is needed or not. I know that I often will see lone apnea events that appear real that don't have any big gulp of air following the event. Maybe the need has something to do with duration and maybe how many events have happened just prior to this event.

I always take this stuff with a grain of salt anyway because in the back of my mind I know that the machine can be fooled with labels or what they call something. They are good but not perfect with the labels.
Now the flow rate shown without labels is going to be accurate.
For me it goes back to the basics in that I don't worry about what something is called as much as I wonder about them if whatever they are called is present in large numbers or they disturb my sleep.

I know the machine can be fooled in some situations so that along with my own lay person interpretation of the flow rate leaves room for potential inaccuracies. I pretty much shrug my shoulders and scratch my head and have to accept that I don't always have nice clear cut answers for my questions.

[Jay Aitchsee]

While not as pronounced as the first, there is a change in breathing prior to the 2nd event as well. Blow it up a bit and have a look.
SWJ usually presents as CA, but sometimes as OA, too. Regardless, only two OA for the night is probably insignificant.

[Pugsy]

Given the regular breathing before and after the events, neither of these two examples look like those cases. What an I missing here?

Arlene's examples above....not as clear cut as some examples might be. Sometimes it's so obvious a blind man could see it and sometimes it takes a real professional to note the subtle differences. I am not that professional. I have been looking at flow rate under the microscope for years now and I am no way comfortable with absolutes.

To me the first image doesn't have normal asleep breathing immediately before the flagged event.
It's irregular and shows bigger gulps of air. Asleep breathing looks like this.



and when the nice boring smooth breathing pattern is broken up with arousals (we may or may not remember them) you get a flow rate that looks like this. Pretty much everything flagged here comes after the obvious arousal..and is SWJ. This one is real obvious....and I did run this by a sleep tech to confirm my ideas about this being all SWJ flags. These are NOT real...they are all SWJ events.



These are likely real and the little blip in breathing after the first flag is likely a bit of recovery breath. Still asleep though.

[Arlene1963]

Thanks folks .... and thanks for those examples, Pugsy.

Here is what I consider to be a true central when I look at my data ... I usually have 2 of these per night. On my sleep studies I had two over the whole night on both studies so I would say this is fairly accurate.

I look at tidal volume as well and if it looks fairly regular with no big intakes of breath before the event then I consider that as an indicator of the real deal for a central. In this example it is fairly flat preceding the event.

[CapnLoki]

I'm even more confused - are you claiming that any sign of rough breathing for a minute or so before the event means that its not really apnea? Even if it looked like sound sleep before and after the events? If this is true then I probably don't have any real events! Most of the references to SWJ I've seen are talking about early morning events while wakening.

So the sequence you point to with 4 events that you claim is SWJ, not apnea - are you saying this would not be causing O2 desats, and would not be prevented by a higher pressure?

I'm going to have to pull out some plots from 4 years ago, before I raised pressure and brought AHI down near zero - I certainly have many that show this type of pattern in the middle of NREM sleep, with no wakefulness showing other than rough breathing for maybe 30 seconds before the events. I admit that a few H events in the middle of NREM is very significant, but I do think they are real.

[jnk...]

The trick with all of it is to use trending data to look for indications as to whether a change in pressure(s) might improve someone's sleep. That is a highly individual thing, in practice.

As Pugsy says, in a true clinical NPSG, more information is available to evaluate when an increase in pressure may be warranted. That is especially important for the titration PSG, since usually only one night is available to get an Rx in the ballpark.

On the other hand, if a patient is comfortable tweaking PAP pressures in a responsible way, there is nothing wrong with using anything that looks odd as an excuse for a small tweak to bump pressure, just to see if that improves numbers or, more important, improves how one feels over time week-to-week, month-to-month.

The reason we give names to breathing events/nonevents is simply to have an easy way of keeping a running tab of our breathing trends. It isn't a true diagnostic clearcut evaluation of every single event, and that name-giving is not what makes PAP therapy successful over time.

That said, one of the joys of this forum is getting some sense of how to make sense of squiggly lines in reports. A person's individual circumstance is a key, though, to knowing how applicable someone else's breathing patterns are to our own.

In my opinion.

[Pugsy]

So the sequence you point to with 4 events that you claim is SWJ, not apnea - are you saying this would not be causing O2 desats, and would not be prevented by a higher pressure?

Are you talking about this example? Then yes....all the flagged events are SWJ and not real apneas and wouldn't be causing desats and wouldn't be prevented by a higher pressure or any pressure for that matter. This person doesn't have OSA confirmed in an in lab sleep study. And I ran all this by a sleep lab tech BTW. It's wasn't just me making a wild ass guess. I got professional input for this one and this example is but one segment of crappy sleeping out of maybe 50 such segments this person had.

I'm even more confused - are you claiming that any sign of rough breathing for a minute or so before the event means that its not really apnea?

No. Not saying that at all. I am just saying that the signs of rough breathing COULD mean an arousal and the flagged event might not be real.
Some situations it's a fairly easy decision and some it isn't. It's not always clear cut black and white.
If the irregular breathing immediately precedes the flagged event...then the validity of the flagging comes into question in terms of "real" vs "SWJ".
In Arlene's top example with the obvious arousal breathing it isn't clear cut but I would lean towards SWJ myself.
For all we know that was a very brief post REM stage sleep arousal and a little SWJ as a result.
For Arlene's example...I am LEANING towards SWJ...that's all I am saying.
For the example with the 4 flagged events with all the irregular breathing...Not leaning towards SWJ...stating it as fact SWJ and have professional input to back me up.

[TASmart]

The trick with all of it is to use trending data to look for indications as to whether a change in pressure(s) might improve someone's sleep. That is a highly individual thing, in practice.

As Pugsy says, in a true clinical NPSG, more information is available to evaluate when an increase in pressure may be warranted. That is especially important for the titration PSG, since usually only one night is available to get an Rx in the ballpark.

On the other hand, if a patient is comfortable tweaking PAP pressures in a responsible way, there is nothing wrong with using anything that looks odd as an excuse for a small tweak to bump pressure, just to see if that improves numbers or, more important, improves how one feels over time week-to-week, month-to-month.

The reason we give names to breathing events/nonevents is simply to have an easy way of keeping a running tab of our breathing trends. It isn't a true diagnostic clearcut evaluation of every single event, and that name-giving is not what makes PAP therapy successful over time.

That said, one of the joys of this forum is getting some sense of how to make sense of squiggly lines in reports. A person's individual circumstance is a key, though, to knowing how applicable someone else's breathing patterns are to our own.

In my opinion.

========

from a statistical process control trying to minimise variation and stablise a process
you should not be making changes based on one event

if you see the same thing for a week then it might be worth trying to change something
but give it a week to evaluate the results

dont keep tweaking daily trying to chase some new blip on the chart that may or may not be significant

If as you constantly harp we all should be on APAP because the constant variation of our various factors causing sleep apnea requires constant adjustment, then the concept of SPC doesn't work. The process is fundimentally subject to such large variations that statistical process control is meaningless. Which is it?

[chunkyfrog]

Researchers should be reading this.
The resident experts here have observations that might throw light on the science of sleep medicine.
The idiot, not so much . . .

[jnk...]

Researchers should be reading this.
The resident experts here have observations that might throw light on the science of sleep medicine.
The idiot, not so much . . .

Yep.

The establishment would dismiss most of what is discussed here about our use of trending data as being strictly anecdotal among a preselected exceptional population.

But thing is, when there is a preponderance of anecdotal evidence among any population, especially in a public setting like this, it really should, just as you say, be taken more seriously by researchers as a direction worthy of further exploration using scientific methods.

Dismissing offhand any collection of evidence that does not conform to standard methods is one way many present-day scientists have carelessly blinded themselves with the two-ended poker of "evidence-based medicine" as they understand that term based on arbitrary preconceived notions.

In other words, I again agree with the frog.