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Resmed S9 Autoset question
#11
Thanks for this info Zonk. That's very good info about the algorithm of the S9 Autoset.
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#12
(04-26-2012, 02:04 PM)projman65 Wrote: Your explanation makes sense...so I guess it doesn't really adjust the pressure breath to breath.

while the manufacturer's FAQ says that it does "adjust breath by breath", the very next item in the FAQ explains that it samples data over a 5 breath period. i find those hilariously contradictory, but whatever.

instead of: breath by breath
think of it as: breath-breath-breath-breath by breath.
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#13
Oh you better watch out,
you better not cry.

You better not pout
I'm tellin' you why....

Resmed knows if you're about to die............
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#14
(07-10-2014, 04:14 PM)jrrs Wrote:
(04-26-2012, 02:04 PM)projman65 Wrote: Your explanation makes sense...so I guess it doesn't really adjust the pressure breath to breath.

while the manufacturer's FAQ says that it does "adjust breath by breath", the very next item in the FAQ explains that it samples data over a 5 breath period. i find those hilariously contradictory, but whatever.

instead of: breath by breath
think of it as: breath-breath-breath-breath by breath.
The statements are NOT contradictory.

The S9 has to compare each breath to something in order to figure out what to do next. And it compares the current breath to a running average of the last 5 breaths. (I actually think it's keeping track of more than one running average when it comes to scoring events.)

If the current breath is substantially smaller than the previous 5 breaths it starts timing how long the reduced breath size is in order to (potentially) score a hypopnea. If there's been no air movement for 5-6 seconds, it start the FOT algorithm in preparation to score an apnea if the "no air movement" lasts for a total of 10 seconds.

If the current breath looks much more ragged than the previous 5, the flow limitation curve will start to increase and if the current breath is ragged enough, the pressure will start to increase.

Back to the original question: Why didn't the S9 reduce the pressure after the OP woke up? The S9 has NO idea that you are awake and wake breathing is a lot more irregular than sleep breathing. AutoPAPs will often score Flow Limitations during wake breathing, as well as H's, CAs, and even OAs. And the S9 reacts pretty aggressively to flow limitations.

Look at the flow graph, the flow limitation graph, and the pressure graph together during the time that you know you were awake and looking at the S9's LCD. There may be a lot more raggedness than you would expect with your normal wake breathing.

And then there's also this: The S9 is very quick to increase the pressure: Under the right circumstances it will increase the pressure by as much as 1-2 cm/minute for 5-10 minutes, resulting in a 10cm rise in pressure. But the S9 reduces the pressure very, very slowly. After a 5-7 cm rise in pressure, it may take the S9 20-30 minutes to lower that pressure back down.
Questions about SleepyHead?
See my Guide to SleepyHead
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#15
(07-10-2014, 04:14 PM)jrrs Wrote: while the manufacturer's FAQ says that it does "adjust breath by breath", the very next item in the FAQ explains that it samples data over a 5 breath period. i find those hilariously contradictory, but whatever.

Yup, you have to take manufacturers' claims carefully. They may make you think they mean one thing, then you find out they meant something else. It's like they're trying to sell their product rather than describe it accurately. Too-funny

So in this case you might think that the pressure changes breath by breath. It's 7 for this breath, 10 for the next, 5 for the one after that, and so forth. But as RobySue explained, that's not what they mean.

And then you realize, well, duhh, of course!

This is the nature of the culture we live in.
Sleepster
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www.ApneaBoard.com


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#16
yup, you have to get an ST or ASV for breath by breath adjustments.
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