What does the cpap machine do with you have a central?

Logies101 · Post by **Logies101** » Thu Jan 08, 2015 10:26 pm

Please bear with me, dumb question #2...When you experience a central sleep apnea how does the machine react, (assuming you don't have a machine specifically to treat centrals) does it just keep blowing air even though you are not inhaling? Where does all the air go? I know these might sound like weird questions but I really was wondering about it since I do have some centrals at night. Seems like it would just keep building up in your airway/mask or am I not understanding the process correctly?

palerider · Post by **palerider** » Thu Jan 08, 2015 10:41 pm

Logies101 wrote:Please bear with me, dumb question #2...When you experience a central sleep apnea how does the machine react, (assuming you don't have a machine specifically to treat centrals) does it just keep blowing air even though you are not inhaling? Where does all the air go? I know these might sound like weird questions but I really was wondering about it since I do have some centrals at night. Seems like it would just keep building up in your airway/mask or am I not understanding the process correctly?

it doesn't react, unless it's an ASV or a machine with a timed back up rate.
out the vent, just like when you hold your breath for a few seconds.

no, nothing 'builds up', you exhale all night long, doncha

Logies101 · Post by **Logies101** » Thu Jan 08, 2015 10:53 pm

palerider wrote:
Logies101 wrote:Please bear with me, dumb question #2...When you experience a central sleep apnea how does the machine react, (assuming you don't have a machine specifically to treat centrals) does it just keep blowing air even though you are not inhaling? Where does all the air go? I know these might sound like weird questions but I really was wondering about it since I do have some centrals at night. Seems like it would just keep building up in your airway/mask or am I not understanding the process correctly?
it doesn't react, unless it's an ASV or a machine with a timed back up rate.
out the vent, just like when you hold your breath for a few seconds.

no, nothing 'builds up', you exhale all night long, doncha

Got it

TangledHose · Post by **TangledHose** » Thu Jan 08, 2015 10:58 pm

PR has answered your question, so I am just making a comment..........I think it's interesting to zoom in on the flow graph in Sleepyhead.....Zoom in as far as it goes and you'll see the small little FOT pulses that the machine puts out to determine if you are having a central or an obstruction.......just kinda cool to see the machine doing it's thing in the flow graph. A couple times over the last couple years I have actually felt the FOT pulses while on my S9.....it's rare that you get to feel them because most of the time you are very much asleep when it happens, but every now and then I feel them and it kinda makes me chuckle that I am awake and feel them............it's only happened about twice in a year tho.

palerider · Post by **palerider** » Thu Jan 08, 2015 11:13 pm

many times you can see a difference in the FOT on the mask pressure, if it's fuzzy an indistinct, it's probably a central, if it's sharper and more defined, it's probably an obstructive

Suenyo · Post by **Suenyo** » Thu Jan 08, 2015 11:24 pm

Aha! So that's what the little square red dots mark? An FOT (Failure of The ?) I see there is a little blip just under the dot.

palerider · Post by **palerider** » Fri Jan 09, 2015 12:12 am

Suenyo wrote:Aha! So that's what the little square red dots mark? An FOT (Failure of The ?) I see there is a little blip just under the dot.

resmed machines attempt to detect the difference in a OA and CA by FOT (Forced Oscillation Technique) which is a 4hz 1cm oscillation of the pressure, by measuring the pressure response to the oscillation waveform in the airflow. if the pressure response is sharp, then the airway is likely blocked, however, if the pressure response is muted. then it's probably just wiggling the big balloons of your lungs, meaning your airway is open, and it's a central.

respironics uses a single bump in pressure and watches the response to that, they call it a pressure pulse. that may be what the little blocks are.

my guess is that they do that because the blowers in their 60 series machines aren't responsive enough to generate a FOT. (or, it could be patent issues, however, I believe respironics uses FOT in their trilogy NIV machines... which casts doubt on the patent theory).

you can hear the PP if you take your mask off and let it blow, after a bit, you'll hear the airflow rate increae briefly (half a second or so) every few seconds, that's it pulsing.

you can see FOT happening below between 6:52:21 and 6:52:28 on the mask pressure trace.

Wulfman... · Post by **Wulfman...** » Fri Jan 09, 2015 12:31 am

The difference in the techniques could also depend on who owns what patents/copyrights, etc.
It may have been Puritan Bennett who first used the FOT technology in their 420E machines about a decade ago.
Maybe ResMed got "dibs" on that technology (paid $$$) after Tyco got out of that market.

Den

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palerider · Post by **palerider** » Fri Jan 09, 2015 9:35 am

Wulfman... wrote:The difference in the techniques could also depend on who owns what patents/copyrights, etc.
It may have been Puritan Bennett who first used the FOT technology in their 420E machines about a decade ago.
Maybe ResMed got "dibs" on that technology (paid $$$) after Tyco got out of that market.

I thought I offered that possibility *scratching head*.

not knowing the ancient history of cpap too well, I'd thought FOT was a resmed thing, then I heard Madalot talking about the FOT on her respironics trilogy bothering her, and as far as my bit of curious digging could tell me, it's the same thing, not just something else using the same initials.

having examined the blower motors in the prs1 and the s9 machines, I believe that resmed came up with a considerably more responsive twin turbine unit that has a much lower moment of inertia, and as such can change speeds fast enough to generate a FOT signal. (a lot less of the inside of a s9 is actual blower than the inside of a prs1) at a glance, I 'd say the resmed turbine assembly is half the diameter of the prs1, which looks like the old m series motor.

Wulfman... · Post by **Wulfman...** » Fri Jan 09, 2015 5:55 pm

There have been lots of discussions on FOT on this forum in the past.
From my searching, it would appear that ResMed and the others may have used it over the years.

Here are some links to help put you to sleep.......

Den

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viewtopic/t40904/Discussion-on-Resmed-A ... tents.html

An early discussion.

viewtopic/t40904/viewtopic.php?f=1&t=42 ... que#p34544

viewtopic/t40904/viewtopic.php?f=1&t=16 ... ue#p141129

viewtopic.php?f=1&t=29851

viewtopic/t40904/viewtopic.php?f=1&t=29 ... ue#p261260

viewtopic.php?f=1&t=44347

viewtopic/t40904/viewtopic.php?f=1&t=44 ... ue#p397333

viewtopic.php?f=1&t=16570

viewtopic/t40904/viewtopic.php?f=1&t=44 ... 0E#p397415

http://www.google.com.mx/patents/EP1905049A1?cl=en

http://mgcdiagnostics.com/products/view ... scillation

http://mgcdiagnostics.com/images/produc ... -001rB.pdf

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What does the cpap machine do with you have a central?

What does the cpap machine do with you have a central?

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