Variable Breathing

I understand that some variable breathing is a good thing as it happend during REM sleep. Does anyone know what a reasonable range is for percentage of time spent in variable breathing?

Susan

Fraction of Time in Variable Breathing: "Variable breathing" is defined as the situation when a person is not undergoing the quiet steady breathing of several stages of sleep. In particular, according to the Respironics patent" it happens during wakefulness, distress, and REM sleep. This chart may be taken as an indication of how "peaceful" a night was. Since REM sleep is a desirable state, some variable breathing is obviously a good thing.

This is from the cpaptalk article on MyEncore.

myencore.php


I don't know about a percentage of time, I think the point is that REM causes variable breathing.

This breathing pattern is not controlled by the chemoreceptors, but is due to the activation of behavioral respiratory control system by REM sleep processes

http://en.wikipedia.org/wiki/Sleep_and_breathing

Cheers

Peter

Spidermonkey wrote:I understand that some variable breathing is a good thing as it happend during REM sleep. Does anyone know what a reasonable range is for percentage of time spent in variable breathing?

Susan

It's tough to take one value and try to figure out what it means without looking at everything else that is occurring. But given that the variable breathing associated with REM is generally not all that variable nor widespread, I would caution against any tendency to equate VB% with REM% (course, it also depends on where the VB threshold is set). The respiratory variation associated with Wake would be a more likely culprit to trigger the VB layer, so the first thing I would look at would be Sleep Efficiency (or how much time is spent tossing and turning). And again, VB is not % of variable breathing per se, but rather how long the machine has been in Variable Breathing Mode (suspension of titration). With that in mind, I'm gonna put my vote in for <5%. If you can document good sleep efficiency and little to no sleep fragmentation, then you can bring up the REM thing. If there ever turns out to be a way to track VB vs when it actually occurs during the night, then we can make a better case for REM VB.
SAG

OK, here comes another one of those giant

Here's an example of REM. There's dramatic movements in the eye channels. These are REMs.


This is a very typical breathing pattern in REM (BTW, this is also a CPAP PSG, so this is what the Respironics machine is actually "seeing").

"Erratic" refers not only to depth, but also (and in this case, a great deal) to rate.

Now an interesting point is also raised about breathing in relation to REMs. There 2 kinds of REM, phasic (or "busy" REM) and tonic (umm, "not busy" REM). There are tons more REMs in phasic REM, and breathing is substantially more erratic. This REM example is obviously of the phasic variety.

As I understand how the Variable Breathing Module works, VB is declared when the mean flow in a 4-minute floating window exceeds an upper threshold. It would make sense for only a sudden increase in flow (depth) of respiration to be the trigger for VBM, because any sudden drops would be picked up in the Apnea-Hypopnea layer as respiratory events. And if it doesn't measure minute ventilation, then rate changes aren't considered at all.

So back to our example, there's a lot of rate change (the breathing waveforms get closer together as the rate increases, and vice-versa), but not a particularly large amount of flow change (except that drop in flow there at 4:07:43, and I wouldn't be surprised if an APAP picked that up as a hypopnea).

But continuing our tendency to be wishy-washy, how much is "much"? That "hypopnea" is undoubtedly a central response to that increase in ventilation immediately prior to it. And if the machine did go into VBM at the point of hyperventilation, then that would be exactly the type of event you wouldn't want to address. Back to "washy", would the 4-minute analysis window (the example above is 5 minutes, and VB isn't based on breath-to-breath) say that the increase isn't that relatively large?

But to interpret variable breathing, I think I'd still be looking at continuity of sleep issues before trying to equate VB with REM (and only phasic REM at that). In other words, VB is probably bad until proven otherwise. If we are able to plot VB against time, and VB seems to occur at points where REM would normally be, then you have some evidence there. If there's a lot of VB at sleep onset, or you know your architecture is a wreck, that should send you in another direction.
SAG

That was quite an explanation! The data you posted looks like sleep lab data--certainly not anything that I could get from Encore Pro etc. I am trying to figure out my sleep efficiency--and am not sure how or if I can do that with the data extracted from my
machine.

Susan

StillAnotherGuest wrote: There 2 kinds of REM, phasic (or "busy" REM) and tonic (umm, "not busy" REM). There are tons more REMs in phasic REM, and breathing is substantially more erratic.

I've never head about the two types of REM before. Are there books or papers somewhere discussing this in more detail?

-james

jskinner wrote:I've never head about the two types of REM before. Are there books or papers somewhere discussing this in more detail?

-james

Right, outside of the sleep laboratory, it's not a topic that really pops up a lot. It's certainly in all the textbooks, as is the concept of "REM density%" or "REM density index". I'll browse around and try to find something that isn't copyrighted or that I don't have to type a lot to get. Suffice to say, trying to establish a direct correlation between VB and REM is impossible (how about all those guys on REM-suppressant medications on top of everything else?).

Spidermonkey wrote:That was quite an explanation! The data you posted looks like sleep lab data--certainly not anything that I could get from Encore Pro etc. I am trying to figure out my sleep efficiency--and am not sure how or if I can do that with the data extracted from my machine.

Susan

You may get a clue from your sleep studies. If that night(s) bore any similarity to how you normally sleep, then Sleep Efficiency% or evidence of sleep fragmentation due to causes other than respiratory events might offer an explanation if you have high VB numbers.

While not meaning to create an "Omigod! I've got heart disease!" stampede, in another thread discussing VB:

VBabble I

I had expressed curiosity how Cheyne-Stokes Respiration (CSR) would affect the VB algorithm. I'd be willing to bet CSR would really mess it up, and you'd be getting some staggering VB% numbers.
SAG