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Annals of Understatement
Posted: Sat May 19, 2007 1:07 pm
by GoofyUT
rested gal wrote:st3v3k4hn, I'm no expert on the way autopaps work, but I think the machine probably does a lot of behind the scenes sensing that we aren't going to see reflected in the data.
By that I mean... I believe the machine looks at subtle changes in airflow to decide what to do next. It's not just looking at the events you see tick marked, and then taking action. The marked occurrences are the events that actually happened despite the machine working to proactively prevent "events" -- apneas, hypopneas -- as well as flow limitations, snores.
So, if we see pressure rise with no "event" immediately preceding it, and the leak rate is normal (which I think yours was during the area you highlighted on the graph) my bet would be that the machine was seeing enough flow limitation from you that it decided more pressure was needed. Even if the flow limitation was not "limited enough" to warrant a tick mark on the data.
In the middle of the highlighted area, your breathing might have normalized some for awhile, so the machine did start the gradual move down. But apparently during that pressure drop in the center of the highlighted area your breathing showed signs of a problem again, so the pressure moved back up. It moved back up to PREVENT an event from happening. If the event is prevented and doesn't happen, it's not going to be marked. 'Cause...it didn't happen.
In other words, the machine was seeing problems with your breathing during the highlighted time. The problems just didn't get "worse enough" to trigger the official marking of an event. But the problems did warrant keeping the pressure up.
There was almost surely some amount of flow limitations happening in varying degrees all during the highlighted time for the machine to stay up there so long, try to come down, and then say (in effect) -- "Nah, when I try to move the pressure down, the airflow becomes more limited (restricted) again...gotta go back up BEFORE it turns into an official "flow limitation" or worse.
I could be very wrong about any/all of that. I don't know much about the way autopaps go about doing their thing.
Having RG say that she doesn't know much about how how autopaps work MUST go into the Annals of Understatement. That's like telling someone in SouthEast Asia that they're gonna get damp in the face of an on-coming tsunami. I don't know ANYONE who understands better how the various APAPs worh than does RG.
So, yes, she is right, that some APAPs, particularly those made by Respironics, do lots "behind the scenes" before an event actually happens. And, Den and others are here are incorrect; Resprionics employs a "probing" algorithm that constantly creates small, step-wise increases in its operating pressure throughout the night to determine whether each increase improves flow-dynamics of your breathing. It will keep doing this until it senses no further improvements, and then will mainitain or back down pressure gradually until it begins a new "probe" cycle.
So, in answer to your question, YES, auto-titrating PAPs made by Respironics will demonstrate small increases and decreases in pressure even if NO events are detected and scored, and will do so throughout the night. If it attempts three such increases in the face of what it scores as flow degradations in your breathing with NO improvements after those three steps it will then score the event as a "non-responsive" event (possibly a central event) and then decrease pressure.
Hope this helps.
Chuck
Re: Annals of Understatement
Posted: Sat May 19, 2007 4:13 pm
by Wulfman
GoofyUT wrote:rested gal wrote:st3v3k4hn, I'm no expert on the way autopaps work, but I think the machine probably does a lot of behind the scenes sensing that we aren't going to see reflected in the data.
By that I mean... I believe the machine looks at subtle changes in airflow to decide what to do next. It's not just looking at the events you see tick marked, and then taking action. The marked occurrences are the events that actually happened despite the machine working to proactively prevent "events" -- apneas, hypopneas -- as well as flow limitations, snores.
So, if we see pressure rise with no "event" immediately preceding it, and the leak rate is normal (which I think yours was during the area you highlighted on the graph) my bet would be that the machine was seeing enough flow limitation from you that it decided more pressure was needed. Even if the flow limitation was not "limited enough" to warrant a tick mark on the data.
In the middle of the highlighted area, your breathing might have normalized some for awhile, so the machine did start the gradual move down. But apparently during that pressure drop in the center of the highlighted area your breathing showed signs of a problem again, so the pressure moved back up. It moved back up to PREVENT an event from happening. If the event is prevented and doesn't happen, it's not going to be marked. 'Cause...it didn't happen.
In other words, the machine was seeing problems with your breathing during the highlighted time. The problems just didn't get "worse enough" to trigger the official marking of an event. But the problems did warrant keeping the pressure up.
There was almost surely some amount of flow limitations happening in varying degrees all during the highlighted time for the machine to stay up there so long, try to come down, and then say (in effect) -- "Nah, when I try to move the pressure down, the airflow becomes more limited (restricted) again...gotta go back up BEFORE it turns into an official "flow limitation" or worse.
I could be very wrong about any/all of that. I don't know much about the way autopaps go about doing their thing.
Having RG say that she doesn't know much about how how autopaps work MUST go into the Annals of Understatement. That's like telling someone in SouthEast Asia that they're gonna get damp in the face of an on-coming tsunami. I don't know ANYONE who understands better how the various APAPs worh than does RG.
So, yes, she is right, that some APAPs, particularly those made by Respironics, do lots "behind the scenes" before an event actually happens. And, Den and others are here are incorrect; Resprionics employs a "probing" algorithm that constantly creates small, step-wise increases in its operating pressure throughout the night to determine whether each increase improves flow-dynamics of your breathing. It will keep doing this until it senses no further improvements, and then will mainitain or back down pressure gradually until it begins a new "probe" cycle.
So, in answer to your question, YES, auto-titrating PAPs made by Respironics will demonstrate small increases and decreases in pressure even if NO events are detected and scored, and will do so throughout the night. If it attempts three such increases in the face of what it scores as flow degradations in your breathing with NO improvements after those three steps it will then score the event as a "non-responsive" event (possibly a central event) and then decrease pressure.
Hope this helps.
Chuck
I still stand by my interpretations and assements of the charts I've seen posted here. There were plenty of "events" (leaks, snoring, flow limitations, hypopneas and apneas") going on during those nights to elevate the pressure as it showed on the charts.
"Sensing subtle changes in airflow" could still be an "event" according to the machine's firmware/algorithm/program. The machines are run by program logic......(basically) "If this (condition exists) .....then perform this or this or this.....else this".
If you like that kind of pressure change/volatility all night long......it's YOUR choice.
Den
Pressure changes
Posted: Sat May 19, 2007 4:25 pm
by GoofyUT
REMstar autos will adjust pressure in step-wise increases and decreases whether there are ANY events or not. It is the nature of their "probing" algorithm. It operates under the principle that: "If a little is good, maybe a little more is better."
Chuck
Posted: Sat May 19, 2007 6:34 pm
by DreamStalker
st3v3k4hn wrote:... As I said this was a "bad" night for me. Here is a graph for a more typical night. 90% pressure is at 10 (which was also my titrated pressure) and AHI was close to 1...
Thanks again! Any and all feedback / opinions / advice appreciated!
Steve
You may also notice that your chart for the "more typical" night shows better control of your leaks than your chart for a "bad" night.
Re: Pressure changes
Posted: Sat May 19, 2007 7:20 pm
by Guest
GoofyUT wrote:REMstar autos will adjust pressure in step-wise increases and decreases whether there are ANY events or not. It is the nature of their "probing" algorithm. It operates under the principle that: "If a little is good, maybe a little more is better."
Chuck
Is this why there are all those little bumps in my chart, more like blips, where they go up a notch and then come back down over and over? The line can be straight, but with all these bumps? I've been curious about those.
Re: Pressure changes
Posted: Sat May 19, 2007 8:05 pm
by rested gal
RosemaryB accidentally guested wrote:Is this why there are all those little bumps in my chart, more like blips, where they go up a notch and then come back down over and over? The line can be straight, but with all these bumps? I've been curious about those.
All my graphs with the REMstar Auto (and with the IPAP line of the BiPAP Auto) have always had those same little bump/blips -- usually pretty regularly spaced.
Re: Pressure changes
Posted: Sat May 19, 2007 10:14 pm
by GoofyUT
Anonymous wrote:GoofyUT wrote:REMstar autos will adjust pressure in step-wise increases and decreases whether there are ANY events or not. It is the nature of their "probing" algorithm. It operates under the principle that: "If a little is good, maybe a little more is better."
Chuck
Is this why there are all those little bumps in my chart, more like blips, where they go up a notch and then come back down over and over? The line can be straight, but with all these bumps? I've been curious about those.
Yup...those little bumps are the REMstar's "probes" going on throughout the night.
Cheers!
Chuck
Posted: Sun May 20, 2007 8:28 am
by Wulfman
AND, only doing what it's program tells it to do in conjunction with its sensors detecting "conditions" or "events" that are defined in the programs/firmware/algorithms.
Since we don't have access to their program sources, we don't know exactly what those defined conditions and events may be. And, since it's based primarily on air flow (with the possible exception of snore detection), two different individuals may have different results based on how they breathe when they sleep.
Ever wonder why the machines are different firmware levels? The "classic" machines I own have versions 2.5 and 2.7 in them. When I sent my Pro 2 back to the factory late last summer, it had a 2.5 in it when it left and a 2.7 when it came back. (now it wants to drop 10 minutes at the beginning of the night where it didn't before.....but I figured out how to make it NOT do that)
Obviously, their programmers are re-writing and upgrading the programs/firmware.....and we really don't know what it is they're changing.
These are "DUMB" machines and, like computers, will only do what they are programmed to do in response to a predefined "condition" or "event".....(in a computer, it would be) keystroke, mouse click, new hardware detection, etc., etc.
This is (another) one of the reasons I use single pressure.....I don't have to look at or think about those little "bumps" in my pressure graph. They don't wake me up and I get excellent therapy without them......Nanner, nanner.
Den
Re: Pressure changes
Posted: Sun May 20, 2007 8:55 am
by GoofyUT
GoofyUT wrote:REMstar autos will adjust pressure in step-wise increases and decreases whether there are ANY events or not. It is the nature of their "probing" algorithm. It operates under the principle that: "If a little is good, maybe a little more is better."
Chuck
Re: Pressure changes
Posted: Sun May 20, 2007 10:28 am
by Wulfman
GoofyUT wrote:GoofyUT wrote:REMstar autos will adjust pressure in step-wise increases and decreases whether there are ANY events or not. It is the nature of their "probing" algorithm. It operates under the principle that: "If a little is good, maybe a little more is better."
Chuck
OK. Let's take a look at your terminology......
I just put the words "probing" and "algorithm" into a MS Word document and then looked up the synonyms/definitions. They ALL correlate to what sensors would do in an AutoPAP....."sensing" and "testing".....not the "pro-actionary" way you're trying to imply it. NO action wil result without a "sensed" (detected) condition occurring......PERIOD!
probing
Synonyms:
inquisitive
inquiring
snooping
interested
questioning
nosy
prying
Algorithm
a logical step-by-step procedure for solving a mathematical problem in a finite number of steps, often involving repetition of the same basic operation
a logical sequence of steps for solving a problem, often written out as a flow chart, that can be translated into a computer program
It's ALL going on "behind the scenes"......whether it shows it in the software reports or not. Remember.....WE aren't supposed to have the software, anyway. (it's only for the medical professionals.....we couldn't possibly understand it)
Den
Posted: Sun May 20, 2007 11:30 am
by Slinky
Well, they're partially right there. Most of those "graphs" produced by the Respironics leave me totally baffled!!! On the other hand, I really like the Daily Events Per Hour table. THAT I CAN understand.
The Resmed "graphs" I "can" understand.
Leaks
Posted: Sun May 20, 2007 5:22 pm
by st3v3k4hn
DreamStalker wrote:You may also notice that your chart for the "more typical" night shows better control of your leaks than your chart for a "bad" night.
I agree that leaks seem to be driving many (most?) of my highest pressures. I am trying to stop the leaks but I don't want to go to a full face mask or start taping. Would reducing my top pressure help (to stop the leak raising pressure increasing the leak cycle)? I was titrated at 10 and on good nites I am 90% at 10 or less...
Steve
PS - by the way, i recently switched from straight CPAP to A-PAP so please don't suggest going back to straight CPAP, I am trying to improve things not go back to how things were, thanks...
Re: Leaks
Posted: Sun May 20, 2007 7:49 pm
by Wulfman
st3v3k4hn wrote:DreamStalker wrote:You may also notice that your chart for the "more typical" night shows better control of your leaks than your chart for a "bad" night.
I agree that leaks seem to be driving many (most?) of my highest pressures. I am trying to stop the leaks but I don't want to go to a full face mask or start taping. Would reducing my top pressure help (to stop the leak raising pressure increasing the leak cycle)? I was titrated at 10 and on good nites I am 90% at 10 or less...
Steve
PS - by the way, i recently switched from straight CPAP to A-PAP so please don't suggest going back to straight CPAP, I am trying to improve things not go back to how things were, thanks...
OK.......set your bottom pressure at 10 and your top pressure at 11 or 12.
You'll still be in "Auto" mode.
Den