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Pressure from S9 Autoset when wide awake
#1
Question 
I am pretty new to all this and have now bought an S9 Autoset having had mixed experiences with various CPAPS provided free on loan by the NHS in England. (When I have more time I might entertain you all with the well-meaning but sometimes puzzling ways of the totally free health service in the UK). My problem now is that I am using this ResMed machine with a Quattro Air Mask and pressure settings of low 7 and high 16. I sleep fine for about 4 hours but then need a bathroom break. When I get up for this the S9 is showing good results with pressure of about 12 to 13 and AHI of about 4. So far so good. After the break the machine starts fine but as I don't go back to sleep easily it seems to get fed up and ups the pressure gradually and intermittently even though I am still wide awake. My main question then is why is it trying to treat an event when I am wide awake and obviously not having one. Common sense tells me that the machine should run at minimum pressure until I have an apnea. I have asked the hospital and ResMed about this and they are completely fazed by the question which is simple enough in my mind. Not only this but after a few hours of wrestling with the high pressures then going to sleep (or not) the AHI reading is magically increased to some stunning figure much higher than the one when I got out of bed for the bathroom break ( I have had 18.7 on one occasion!!). On no occasion has the machine shown a leakage level greater than 10 and it is usually much lower than that.

I would be eternally grateful for some advice about all this from all you wise and obviously very expert people please. I am still full of hope that I will eventually get a good nights sleep but at times I feel inclined to just throw the machine inti the River Wye which meanders gently past the house.

Please help!!
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#2
Our breathing pattern while awake is different than while asleep and apnea events that occur during awake periods are meaningless and does not count as the machine unable to differentiate between the two. AHI is average per hour that include obstructive/hypopnea/central/unknown apnea events which occur while using the machine, before and after bathroom break.

If you,re getting the numbers from LCD screen, you need to download either Resscan (does work with Mac computers) or Sleepyhead software so you get better idea of whats going on
Talk to your doctor about using the machine on CPAP mode so it deliver a constant pressure all night except ramp time if used, titration pressure is good start. This might don,t make any significant difference but are you changing mask setting to the type of mask are using, Nasal for nasal mask, etc ..

In my experience, having stuffy nose not breathing properly can cause big jump in AHI, your mileage may vary

Software download http://www.apneaboard.com/forums/Forum-P...-and-Links

Post Reply Post Reply
#3
(12-13-2013, 12:03 PM)Brian Rule Wrote: I sleep fine for about 4 hours but then need a bathroom break. When I get up for this the S9 is showing good results with pressure of about 12 to 13 and AHI of about 4. So far so good. After the break the machine starts fine but as I don't go back to sleep easily it seems to get fed up and ups the pressure gradually and intermittently even though I am still wide awake. My main question then is why is it trying to treat an event when I am wide awake and obviously not having one. Common sense tells me that the machine should run at minimum pressure until I have an apnea.
The machine has no EEG data and, unlike Santa Claus, it does not know when you are awake and when you are asleep. The presumption by the engineers who designed the machine is that if you're using the machine for any length of time, there should be a high probability that you are asleep. Hence the Auto algorithm is based on what the characteristics of what normal sleep breathing should look like and the machine responds by increasing pressure when the breathing pattern does not resemble normal sleep breathing.

But normal sleep breathing and normal wake breathing are two very, very different things. Indeed, sleep breathing and wake breathing are even controlled by different parts of our nervous system. Wake breathing is controlled by the conscious part of our nervous system---the part that we use to control our arms and legs; it's the part that allows us to walk (without thinking too much about walking). Sleep breathing, however, is controlled by the autonomic part of our nervous system---the part that controls the beating of our heart.

And the Auto algorithm is based on what normal sleep breathing is supposed to look like. Normal sleep breathing is much more regular than normal wake breathing is in terms of both respiratory rate and in the depths of the inhalations and exhalations. When we're awake, it's the conscious part of our nervous system that controls our wake breathing. And we do all kinds of things that affect our wake breathing without really thinking about them, but it's still controlled by the conscious part of the nervous system when we're awake. We take an extra deep breath now and then that may have a prolonged exhalation. We sigh. We momentarily hold our breath when we're concentrating on something (and we may not even be aware of this.) We clear our throats. We "sniff" more vigorously through a slightly stuffed up nostril. We take a series of deep, full breaths (think relaxing yoga breaths) and then naturally return to a more shallow breathing pattern.

All this normal amount of variation in wake breathing is capable of fooling an APAP which is programmed to expect the wave flow pattern to be the normal sleep breathing pattern---which is exceptionally regular in terms of the size of the inhalations and the lengths of the breaths. And the auto algorithm kicks in when the detected breathing starts to look "ragged" because it's not super regular and there's too much variation in the size of the breaths. So if you're using the APAP for long periods of time when you are very restless, but awake in bed, your wake breathing can fool the machine into thinking its seeing signs of abnormal sleep breathing.

In other words, if you're lying in bed fighting to get to sleep, your wake breathing can appear very ragged to the machine: If you hold your breath just a bit too long, the machine thinks you might be having an apnea and starts the CA/OA detection algorithm, which on the Resmed involves sending a series of oscillating small changes in pressure. If the machine thinks the air flow has dropped by something like 40-50% from baseline for at least 10 seconds, it will score a hypopnea. And when you're awake a drop of 40-50% in airflow can just me that you were breathing very deeply for a while (maybe as part of conscious relaxation exercises) and you let your breathing return to a more normal depth for your resting, but wakeful breathing. Or as you transition to sleep, the depths of your inhalations naturally become shallower, but relative to the last several minutes of wake breathing, the new "sleep breathing" inhalations meet the 40-50% reduction needed to flag a hypopnea. And if the machine scores two apneas or hyponeas with in a minute or two of each other, it's going to increase the pressure. And the pressure increase startles you back to full wake status and the cycle starts over ...

Also consider this: As part of its Auto algorithm the machine is measuring the shape of each and every inhalation in the wave flow data and comparing it to an expected shape for an unobstructed open airway during sleep breathing. Certain changes in the shape of the inhalation part of wave flow for sleep breathing are thought to indicate that the airway is beginning to collapse; these changes are called flow limitations and your S9 Autoset responds to flow limitations by increasing the pressure. And here again, the things that we do during wake breathing can fool the Auto algorithm into thinking that it is seeing flow limitations, and so it starts to increase the pressure because the machine has no way of knowing that you are awake.

Finally, the S9 Autoset will increase the pressure when it thinks it is detecting snoring. Since there is no microphone to pick up the audible noise of snoring, the machine is using certain characteristics in the wave flow that are strongly associated with snoring during sleep breathing. But a few people will occasionally have a relaxed wake breathing pattern that can fool the machine into thinking it is picking up snoring, and so the machine increases the pressure ....

So the net result of all this is: The Auto algorithm can misinterpret normal wake breathing patterns as evidence of problematic sleep breathing, and hence it increases the pressure even though you're wide awake.

Quote:I have asked the hospital and ResMed about this and they are completely fazed by the question which is simple enough in my mind. Not only this but after a few hours of wrestling with the high pressures then going to sleep (or not) the AHI reading is magically increased to some stunning figure much higher than the one when I got out of bed for the bathroom break ( I have had 18.7 on one occasion!!). On no occasion has the machine shown a leakage level greater than 10 and it is usually much lower than that.
Excessive restlessness while using the machine often leads to it scoring a whole lot of "false" events.

As to what to do: It sounds like what's happening is that after that bathroom break you get trapped in a nasty, positive feedback loop that looks like this:
  • ... ragged but normal wake breathing is misinterpreted by the machine as abnormal sleep breathing which leads to a pressure increase which leads to more restlessness which leads to ragged but normal wake breathing which is misinterpreted by the machine as abnormal sleep breathing which leads to an increase in pressure which leads to more restlessness which leads to more ragged, but normal wake breathing which is misinterpreted by the machine as abnormal sleep breathing which leads to an increase in pressure which leads to ...

You get the picture. The obvious thing is that you need to decrease the restlessness that occurs after that bathroom break. If you were getting back to sleep as quickly as you get to sleep at the beginning of the night, then this problem would disappear. So the question becomes, what kind of things can you do to decrease the restlessness? And what's triggering the restlessness in the first place?

So some questions:

1) Pre-CPAP did you have one or more bathroom breaks during the night? If you did, did you have the same trouble getting back to sleep pre-CPAP that you are currently having now?

2) Can you identify what is causing the restlessness? Does the problem start as soon as you mask up? Or does it start after you notice the pressure increases?

3) Are you using the ramp? If you are using the ramp, it may be that the linear pressure increase during the ramp period starts making you get more restless and increases your wakefulness, but the wakefulness, that's the start of the negative feedback loop. If you think this might be the problem, then turning off the ramp might go a long way in fixing your problem.

Finally a suggestion: If you haven't gotten back to sleep in about 20 minutes or so after that bathroom break, you may do better to just get out of bed and go into a different room and do something relaxing (not work related) for a while until you start to get sleepy enough where you won't be so restless when you mask back up. Because the sooner you actually fall back asleep with the mask on, the less likely you are to get trapped in the feedback loop of "restlessness triggers the machine scoring false events which triggers pressure increases which triggers more restlessness ...."



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#4
Hi Brian,
WELCOME! to the forum.!
What robysue said.
Hang in there for more responses to your post.
trish6hundred
Post Reply Post Reply
#5
(12-13-2013, 01:33 PM)robysue Wrote:
(12-13-2013, 12:03 PM)Brian Rule Wrote: I sleep fine for about 4 hours but then need a bathroom break. When I get up for this the S9 is showing good results with pressure of about 12 to 13 and AHI of about 4. So far so good. After the break the machine starts fine but as I don't go back to sleep easily it seems to get fed up and ups the pressure gradually and intermittently even though I am still wide awake. My main question then is why is it trying to treat an event when I am wide awake and obviously not having one. Common sense tells me that the machine should run at minimum pressure until I have an apnea.
The machine has no EEG data and, unlike Santa Claus, it does not know when you are awake and when you are asleep. The presumption by the engineers who designed the machine is that if you're using the machine for any length of time, there should be a high probability that you are asleep. Hence the Auto algorithm is based on what the characteristics of what normal sleep breathing should look like and the machine responds by increasing pressure when the breathing pattern does not resemble normal sleep breathing.

But normal sleep breathing and normal wake breathing are two very, very different things. Indeed, sleep breathing and wake breathing are even controlled by different parts of our nervous system. Wake breathing is controlled by the conscious part of our nervous system---the part that we use to control our arms and legs; it's the part that allows us to walk (without thinking too much about walking). Sleep breathing, however, is controlled by the autonomic part of our nervous system---the part that controls the beating of our heart.

And the Auto algorithm is based on what normal sleep breathing is supposed to look like. Normal sleep breathing is much more regular than normal wake breathing is in terms of both respiratory rate and in the depths of the inhalations and exhalations. When we're awake, it's the conscious part of our nervous system that controls our wake breathing. And we do all kinds of things that affect our wake breathing without really thinking about them, but it's still controlled by the conscious part of the nervous system when we're awake. We take an extra deep breath now and then that may have a prolonged exhalation. We sigh. We momentarily hold our breath when we're concentrating on something (and we may not even be aware of this.) We clear our throats. We "sniff" more vigorously through a slightly stuffed up nostril. We take a series of deep, full breaths (think relaxing yoga breaths) and then naturally return to a more shallow breathing pattern.

All this normal amount of variation in wake breathing is capable of fooling an APAP which is programmed to expect the wave flow pattern to be the normal sleep breathing pattern---which is exceptionally regular in terms of the size of the inhalations and the lengths of the breaths. And the auto algorithm kicks in when the detected breathing starts to look "ragged" because it's not super regular and there's too much variation in the size of the breaths. So if you're using the APAP for long periods of time when you are very restless, but awake in bed, your wake breathing can fool the machine into thinking its seeing signs of abnormal sleep breathing.

In other words, if you're lying in bed fighting to get to sleep, your wake breathing can appear very ragged to the machine: If you hold your breath just a bit too long, the machine thinks you might be having an apnea and starts the CA/OA detection algorithm, which on the Resmed involves sending a series of oscillating small changes in pressure. If the machine thinks the air flow has dropped by something like 40-50% from baseline for at least 10 seconds, it will score a hypopnea. And when you're awake a drop of 40-50% in airflow can just me that you were breathing very deeply for a while (maybe as part of conscious relaxation exercises) and you let your breathing return to a more normal depth for your resting, but wakeful breathing. Or as you transition to sleep, the depths of your inhalations naturally become shallower, but relative to the last several minutes of wake breathing, the new "sleep breathing" inhalations meet the 40-50% reduction needed to flag a hypopnea. And if the machine scores two apneas or hyponeas with in a minute or two of each other, it's going to increase the pressure. And the pressure increase startles you back to full wake status and the cycle starts over ...

Also consider this: As part of its Auto algorithm the machine is measuring the shape of each and every inhalation in the wave flow data and comparing it to an expected shape for an unobstructed open airway during sleep breathing. Certain changes in the shape of the inhalation part of wave flow for sleep breathing are thought to indicate that the airway is beginning to collapse; these changes are called flow limitations and your S9 Autoset responds to flow limitations by increasing the pressure. And here again, the things that we do during wake breathing can fool the Auto algorithm into thinking that it is seeing flow limitations, and so it starts to increase the pressure because the machine has no way of knowing that you are awake.

Finally, the S9 Autoset will increase the pressure when it thinks it is detecting snoring. Since there is no microphone to pick up the audible noise of snoring, the machine is using certain characteristics in the wave flow that are strongly associated with snoring during sleep breathing. But a few people will occasionally have a relaxed wake breathing pattern that can fool the machine into thinking it is picking up snoring, and so the machine increases the pressure ....

So the net result of all this is: The Auto algorithm can misinterpret normal wake breathing patterns as evidence of problematic sleep breathing, and hence it increases the pressure even though you're wide awake.

Quote:I have asked the hospital and ResMed about this and they are completely fazed by the question which is simple enough in my mind. Not only this but after a few hours of wrestling with the high pressures then going to sleep (or not) the AHI reading is magically increased to some stunning figure much higher than the one when I got out of bed for the bathroom break ( I have had 18.7 on one occasion!!). On no occasion has the machine shown a leakage level greater than 10 and it is usually much lower than that.
Excessive restlessness while using the machine often leads to it scoring a whole lot of "false" events.

As to what to do: It sounds like what's happening is that after that bathroom break you get trapped in a nasty, positive feedback loop that looks like this:
  • ... ragged but normal wake breathing is misinterpreted by the machine as abnormal sleep breathing which leads to a pressure increase which leads to more restlessness which leads to ragged but normal wake breathing which is misinterpreted by the machine as abnormal sleep breathing which leads to an increase in pressure which leads to more restlessness which leads to more ragged, but normal wake breathing which is misinterpreted by the machine as abnormal sleep breathing which leads to an increase in pressure which leads to ...

You get the picture. The obvious thing is that you need to decrease the restlessness that occurs after that bathroom break. If you were getting back to sleep as quickly as you get to sleep at the beginning of the night, then this problem would disappear. So the question becomes, what kind of things can you do to decrease the restlessness? And what's triggering the restlessness in the first place?

What about just switching from the Auto Mode to just the prescribed pressure setting, and bypassing the minimum/maximum setting. Would that help? I suppose you could also use the ramp or not, but maybe the simple CPAP would work best for a time, provided no other triggers for restlessness are discovered?

So some questions:

1) Pre-CPAP did you have one or more bathroom breaks during the night? If you did, did you have the same trouble getting back to sleep pre-CPAP that you are currently having now?

2) Can you identify what is causing the restlessness? Does the problem start as soon as you mask up? Or does it start after you notice the pressure increases?

3) Are you using the ramp? If you are using the ramp, it may be that the linear pressure increase during the ramp period starts making you get more restless and increases your wakefulness, but the wakefulness, that's the start of the negative feedback loop. If you think this might be the problem, then turning off the ramp might go a long way in fixing your problem.

Finally a suggestion: If you haven't gotten back to sleep in about 20 minutes or so after that bathroom break, you may do better to just get out of bed and go into a different room and do something relaxing (not work related) for a while until you start to get sleepy enough where you won't be so restless when you mask back up. Because the sooner you actually fall back asleep with the mask on, the less likely you are to get trapped in the feedback loop of "restlessness triggers the machine scoring false events which triggers pressure increases which triggers more restlessness ...."

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#6
How about just switching of the Auto function and bypassing the minimum/maximum setting and just a simple CPAP for the doctor prescribed pressure? If that is only partially successful, how about trying the ramp function in both the on and off positions? Finally, if this suggestion makes any sense, would you want to try it as a last resort after not finding any other triggers for restlessness, or try it first? Let me add that I had what appears on the surface to be similar problems during my recent sleep study last week; however, I don't get my S9 AutoSelect until next week.
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#7
(12-13-2013, 01:24 PM)zonk Wrote: Our breathing pattern while awake is different than while asleep and apnea events that occur during awake periods are meaningless and does not count as the machine unable to differentiate between the two. AHI is average per hour that include obstructive/hypopnea/central/unknown apnea events which occur while using the machine, before and after bathroom break.

If you,re getting the numbers from LCD screen, you need to download either Resscan (does work with Mac computers) or Sleepyhead software so you get better idea of whats going on
Talk to your doctor about using the machine on CPAP mode so it deliver a constant pressure all night except ramp time if used, titration pressure is good start. This might don,t make any significant difference but are you changing mask setting to the type of mask are using, Nasal for nasal mask, etc ..

In my experience, having stuffy nose not breathing properly can cause big jump in AHI, your mileage may vary

Software download http://www.apneaboard.com/forums/Forum-P...-and-Links
Also don,t rule out the possibility that machine might be faulty
Welcome

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#8
Since you are not using any software, the data you are seeing is extremely limited. Follow the suggestions of the more experienced and get Sleepyhead or Rescan. This one thing may be the most important at this stage. With the help of others, the data may help explain.

Since you are new, in my opinion, everything that can go wrong will go wrong in the beginning. Most of the crazy stuff fades with time. One thing that might be happening, it did with me, is that when I got frustrated about NOT sleeping, I became more agitated which makes going back to sleep near impossible. I know it's easy to say and harder to do, but if you can relax, natural sleep will come easier. It took me about 3 months to get comfortable. It WILL come.

By the way, I normally take my mask off as soon as I wake. A couple of times I just laid there awake...you know thinking about stupid things. When I looked at my data during a time that I knew I was wide awake, it looked like a San Franciso earthquake seismograph. I just laughed and ignored it. I knew it was B.S.
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#9
G'day Brian, welcome to the club.

As always, RobySue has given a really detailed explanation (she does my head in sometimes, she knows so much stuff Smile )

One thing that was touched on above is the ramp feature. This allows the machine to gradually increase pressure from a very low base to the working pressure over a period of time. On the S9, it is adjustable between 5 and 45 minutes. During the ramp period, the machine will record hypopneas but won't respond to them. As RobySue said, it's likely that you're awake at this time, so those hypos are meaningless. What the ramp does do, is allow you to settle down and (hopefully) get to sleep before the machine starts building up the pressure to maintain your airway and treat events.

A lot of the more experienced users here don't need the ramp any more and just set it to off. I find that I need about 10 minutes - it's enough time to get to sleep without recording too many spurious hypopneas. I suggest you use the ramp, set it for maybe 30 - 45 minutes to start with, then adjust as required. If it doesn't help, you can always turn it off.
DeepBreathing
Apnea Board Moderator
www.ApneaBoard.com


Bed

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#10
(12-13-2013, 04:07 PM)drgrimes Wrote: Since you are not using any software, the data you are seeing is extremely limited. Follow the suggestions of the more experienced and get Sleepyhead or Rescan. This one thing may be the most important at this stage. With the help of others, the data may help explain.

Since you are new, in my opinion, everything that can go wrong will go wrong in the beginning. Most of the crazy stuff fades with time. One thing that might be happening, it did with me, is that when I got frustrated about NOT sleeping, I became more agitated which makes going back to sleep near impossible. I know it's easy to say and harder to do, but if you can relax, natural sleep will come easier. It took me about 3 months to get comfortable. It WILL come.

By the way, I normally take my mask off as soon as I wake. A couple of times I just laid there awake...you know thinking about stupid things. When I looked at my data during a time that I knew I was wide awake, it looked like a San Franciso earthquake seismograph. I just laughed and ignored it. I knew it was B.S.

I'm getting my S9 AutoSelect next week and was encouraged by the sleep study people to use it for an hour or so during the day as a way to adjust to the breathing, since I had lots of problems during the sleep study.

I want to keep my data in ResScan as clean as possible, but I also want to get used to CPAP during the time I'm awake. Is there a way to prevent the awake data from being recorded with the legitimate nighttime data when I'm asleep?

Can you or anyone else suggest the best way to go about this? For example, I suppose I could just remove the SD card, but then I would be losing compliance data, which I would be willing to do if that was the only way.

Finally, on another note, I see things like "Attachment 591" in the body of a post, but I don't see the actual attachment, nor does anything happen when I click on it. I've looked all over the Help section and the Attachment area only talks about "posting" an attachment. Help?
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