Concerned/Worried - New Air Sense 11 AHI High

Forgot one important detail. I wore the mask for another 20 minutes or so, but didn't fall asleep. AHI was then 19.

Hi All,

Can anyone explain how a CPAP, specifically the air sense 11, calculates AHI? I just got a new machine and doc gave me the air sense 11. I was using an air sense 10 previously. New machine has same exact settings as air sense 10.

I took a 45 minute nap today and AHI read as 57.5. Is this accurate? I kind of freaked out since I never had a number that high. My AHI without treatment is normally between 19-22.

Background: Been using the Air Touch F20 (Foam) full face mask since being diagnosed with sleep apnea a few years ago. The Air Touch has always worked well and AHI was 0.3 - 1.0. Recently (last couple of months) the cushions seem to be leaking a lot (even new ones) and I've noticed AHI increasing, but not higher than 15.5. So, I decided to test different masks to see if it was the Air touch leak causing an increase in AHI. I switched to AirFit F20 full face (silicone) and it sealed much better. AHI went back down to 0.3 to 1.0 problem solved I thought. In the meantime my air sense 10 crapped out, and got the air sense 11 in its place. Air touch is more comfortable and I prefer it. Thus, I was wasn't ready to throw in the towel on the air touch.

So, I tested with the Air Sense S11 with both masks and both new cushions on different nights. Results:

When I use the Air Fit F20, AHI was again between 0.3 to 1.0. However, each time I use the Air Touch F20, my AHI goes back up to between 11.5 - 15.5. This number is in line with the reading I got on the Air Sense 10. Until today, using the Air Touch for this nap, I woke up to the 57.5 AHI. Yikes!!!

So, looks like the air touch is going in the trash bin. I'm wondering if the air sense 11 belongs in the trash as well. lol. I plan on calling the doctor if it continues, but was hoping someone may be able to help in the meantime. I am also going to use OSCAR tonight and see what that shows. I wish I had used OSCAR the past couple of weeks, but I didn't. Hind sight.

I will post OSCAR results tomorrow with air fit F20 mask on the air sense 11. I do like the S11, but I'm having trust issues with the machine now. lol.

Thanks everyone.

All xPAPs work the same way in how they calculate the AHI:

Each manufacturer has an algorithm that uses the flow rate to determine when an apnea or hypopnea may have occurred. The apnea algorithm is usually pretty simple: Little or no air flow into or out of the lungs has been detected for at least 10 seconds. Machines like the Resmed then use proprietary technique called FOT to determine whether the airway appears to be open/clear or obstructed and then classifies the apnea as a CA (clear airway) or OA (obstructed airway) depending on the results of the FOT algorithm.

To detect hypopneas, the machine has to calculate a running "baseline" of what the airflow look likes, and if the airflow drops by something like 50% from the running baseline for more than 10 seconds, a hypopnea is scored.

To calculate the AHI, the machine simply divides the total number of events scored by the run time (in hours) in which the events were scored.

Now all of this works reasonably accurately if the person using the machine is asleep for the vast majority the machine is on.

Problems happen, however, when a person uses the machine for an extended period of time while awake or while drifting in and out of real sleep. Wake breathing is simply not as regular as sleep breathing, mainly because different parts of the nervous system control breathing when we're awake versus when we're asleep. And when we're awake, there are all kinds of natural, normal breathing patterns (that we may not even be fully aware of) that can look like apneas or hypopneas in sleep breathing. That's why during a sleep test there should be some kind of mechanism (such as EEG leads) for determining whether the person is actually asleep or is awake: On a sleep test, an apnea or a hypopnea cannot be scored during any epoch where the person is awake.

Forgot one important detail. I wore the mask for another 20 minutes or so, but didn't fall asleep. AHI was then 19.

Because you were awake, that AHI of 19 is genuinely meaningless.

I took a 45 minute nap today and AHI read as 57.5. Is this accurate? I kind of freaked out since I never had a number that high. My AHI without treatment is normally between 19-22.

I suspect (but obviously can't prove) that you were most likely bouncing back and forth between wake and sleep during the nap---i.e. there may be a lot of what rubicon refers to as "sleep-wake-junk" (SWJ) during that 45-minute nap.

Background: Been using the Air Touch F20 (Foam) full face mask since being diagnosed with sleep apnea a few years ago. The Air Touch has always worked well and AHI was 0.3 - 1.0. Recently (last couple of months) the cushions seem to be leaking a lot (even new ones) and I've noticed AHI increasing,

If you've been noticing a lot of leaking with the Air Touch cushions, that might be causing you to arouse all the way to wake to fiddle with the cushion in an attempt to fix the leak. And while you're fiddling with the cushion, you may be unconsciously holding your breath (while awake) just long enough for the machine to score apneas. And it's worth noting, whether a machine scores an CA or an OA when you're holding your breath while awake seems to depend on exactly how you physically hold your breath. In my case, the machine will almost always score an OA, and I suspect that I use my epiglottis when I hold my breath in the same way that I do when I swallow food.

Curious as to what went wrong with your 10.

The 11 series has a hose leak problem... you should be aware of this, with big leaks you're not getting the therapy you need. Check for this and make sure you're not getting this leak... the work-around is to face the machine away from you so the hose comes straight out the back toward you.

https://youtu.be/ZAs01WRPtGk?si=jHSor7ikvWDD6jMD&t=134

Thanks for the detailed answer robysue1! I now understand a bit more of how the machine scores AHI and also the difference between sleep/wake breathing. I never heard of the SWJ, but after researching I see how the machine could be scoring what it believes are apneas/hypopneas while not really asleep. Ever since starting CPAP (2020), I've struggled with delayed sleep/drifting in and out of sleep. Sleep lab noticed the same thing when they did my study. At least I do fall asleep eventually.

vandownbytheriver wrote: ↑

Fri May 24, 2024 9:41 pm

Curious as to what went wrong with your 10.

The motor was making a lot of noise and the pressure wasn't accurate.

vandownbytheriver wrote: ↑

Fri May 24, 2024 9:41 pm

The 11 series has a hose leak problem... you should be aware of this, with big leaks you're not getting the therapy you need. Check for this and make sure you're not getting this leak... the work-around is to face the machine away from you so the hose comes straight out the back toward you.

Thank you for mentioning this issue. I watched the video and the climate line comes out way too easily. I don't use the climate line in the summer months, so no issue for me right now. I do use it sometimes in the winter though, so it is good to know this workaround. I don't suspect Resmed will fix the issue.

As an update, I used a Fisher Paykel Vitera last night and leak rate was low. AHI was 1.69 after 4:45 hours of sleep. One apnea was scored/along with some hypopneas that all seem related to mask leak, I think...LOL. Not great at reading OSCAR.

Not a great night sleep in terms of hours, but I noticed a difference in that I felt more awake in the morning. I tried to upload my OSCAR report for last night, but I can't figure how to do it through Imgur. I tried to follow instructions from the forum, but I can't seem to get a link that works.

Thanks again for the help!

Movieman wrote: ↑

Sat May 25, 2024 6:44 pm

The motor was making a lot of noise and the pressure wasn't accurate.

The motor is easily replaced and is 130USD on Amazon or Alibaba.

Not a great night sleep in terms of hours, but I noticed a difference in that I felt more awake in the morning. I tried to upload my OSCAR report for last night, but I can't figure how to do it through Imgur. I tried to follow instructions from the forum, but I can't seem to get a link that works.
Thanks again for the help!

SleepHQ is actually better for sharing information that Oscar screenshots... it is a free website that you upload your SD card data to. With one link we can see an entire night's data including your settings... you can expire the link at any time and it's anonymous. Here's a recent night of mine, note how you can click and drag to zoom into breaths:

https://sleephq.com/public/13bfec5f-5c8 ... dd6cb6d3a8

Thanks! Much easier. Here is my link.

Thanks for the tip on a new motor. I still have the unit, so maybe I'll look into replacing it. Then, I will have a spare.

https://sleephq.com/public/ab577243-48c ... 5d830597e4

Looks positional... see where your pressure pegged at 10cm? I believe that was when you were flat on your back... lots of Flow Limitations and Snore... wanted even more pressure but limited to 10cm.

The leaks are there but not horrible... the machine was not struggling but was held back by that 10cm limit. Was this the Vitera? What size cushion? I use the Medium and have to pull it downward to put it more on my chin and less up the nose bridge. It should be tighter at the bottom and looser at the top... the cushion inflates like a balloon to create the seal, amazing when it works right. I'm at double your pressure, 21/17cm bi-level... but that lets me go supine no problem. I can put a finger or two between the top frame and my forehead.

So stay off your back and/or let the pressure go higher... keep those leaks down. Looks like it wants you around 8cm base level... IMO.

Movieman wrote: ↑

Sat May 25, 2024 10:54 pm

Thanks! Much easier. Here is my link.

Thanks for the tip on a new motor. I still have the unit, so maybe I'll look into replacing it. Then, I will have a spare.

https://sleephq.com/public/ab577243-48c ... 5d830597e4

Questions and comments:

1) Is this night typical for your usual bedtime and wake up time? The night-time usage of the machine is between 12:40 and 5:25. That's a pretty minimal time in bed. Then add the fact that you turn the machine off and back on at 1:22 and 1:32 means you had at least one extended period of wake or that it took you a while to get to sleep. Most people need more than 5 1/2 hours of sleep each night to feel their best.

2) How long did it take you to get to sleep? In particular, there's a lot of stuff going on between 2:35 and 3:25. Any chance you were awake and tossing and turning during that time period while fighting a low-level, but potentially irritating leak?

3) There's a lot of flow limitations between 2:35 and 3:25. Again, if you were awake or tossing and turning and going back and forth between short wakes and bits of light sleep, this is probably just SWJ breathing. But if you were sound asleep, then something is going on and the machine would increase the pressure past 10cm if it could. The rest of the night is actually pretty decent in terms of the flow limitations. Whether to increase the max pressure or not really depends on what was going on between 2:35 and 3:25 and whether this kind of thing is a common occurrence in your data and you have good reason to believe you are actually sound asleep when this kind of thing is happening.

4) You have a lot of leaks. Whether they're a problem or not is an important question to answer. On the one hand, your leaks stay below the ResMed RedLine of 24 L/min. So they're not affecting the machine's ability to treat your apnea and accurately record hypopneas, OAs, CAs, etc. But on the other hand, those leaks might be repeatedly waking you up just enough to fiddle with the mask (in an attempt to fix them). Or it could be that you're waking up and fiddling with the mask to try to minimize the leaking for longer periods of time than you realize during the night. So what say you? Do you think you're waking up frequently to fiddle with the mask to fix leaks? Do you remember any extended periods of wake where you were fiddling with the mask to try to fix a nasty leak that just wouldn't stop? If so, then troubleshooting the leak problem is well worth it. But if you believe you are sleeping soundly through the leaks, these leaks are not large enough to adversely affect therapy and could be ignored.

5) And finally, there's the all important question: How did you feel when you woke up at 5:25 and started your day? Rested and refreshed? Or tired and feeling like you were tossing and turning or otherwise just got a bad night of sleep?

vandownbytheriver wrote: ↑

Sun May 26, 2024 4:13 am

Looks positional... see where your pressure pegged at 10cm? I believe that was when you were flat on your back... lots of Flow Limitations and Snore... wanted even more pressure but limited to 10cm.

Yes, I did notice that the pressure topped out which was a bit disappointing. I'm hoping this was just a bad night. The reports the past two days look better even on my back. The top pressure was 9cm and only a couple of hypopneas. No doubt my breathing is smoother on my side versus my back, but I had known that.

As background: I had a hard time with CPAP therapy and it took a long time to figure out my current settings and sleep position. You are correct that I was on my back, but not flat. I use a 7" wedge pillow since I had known already that my sleep apnea is twice and bad on my back versus my side. The issue is I need to avoid side sleeping as much as possible due to BPPV episodes. I also had higher settings in the past and was ripping my mask off at night without knowing. My doctor even sent me for a 2nd sleep study a year and half ago at a facility to figure things out. The titration showed that 7cm eliminated all apneas/hypopneas and oxygen desaturation. There were only a few RERAs, I think they are called. However, they really clamp that mask down! I don't do that at home. So, the facility recommended my current settings and to use a wedge pillow since I used it during the sleep study. They recommended leaving the RERAs alone and not raising the max pressure past 10cm since I was pulling off my mask.

vandownbytheriver wrote: ↑

Sun May 26, 2024 4:13 am

The leaks are there but not horrible... the machine was not struggling but was held back by that 10cm limit. Was this the Vitera? What size cushion? I use the Medium and have to pull it downward to put it more on my chin and less up the nose bridge. It should be tighter at the bottom and looser at the top... the cushion inflates like a balloon to create the seal, amazing when it works right. I'm at double your pressure, 21/17cm bi-level... but that lets me go supine no problem. I can put a finger or two between the top frame and my forehead.

Yep,I agree the leaks were not too bad. I was using the Vitera with a large cushion on this night. It was the air touch F20 that was leaking like crazy. I had leak rates of 35ml. I really like the air touch and how soft it feels, but it is apparent to me these cushions are not made the same anymore. The Air Fit sealed well, but shredded my nose bridge. The Vitera irritates my nose bridge, but nothing like the air fit. I also put the vitera on the same way describe and it is much more comfortable than the air fit.

vandownbytheriver wrote: ↑

Sun May 26, 2024 4:13 am

So stay off your back and/or let the pressure go higher... keep those leaks down. Looks like it wants you around 8cm base level... IMO.

If the issue continues, I would consider raising the minimum pressure to 8cm. Hesitant on raising the max pressure though.

Thanks for the help.

robysue1 wrote: ↑

Sun May 26, 2024 10:55 am

1) Is this night typical for your usual bedtime and wake up time? The night-time usage of the machine is between 12:40 and 5:25. That's a pretty minimal time in bed. Then add the fact that you turn the machine off and back on at 1:22 and 1:32 means you had at least one extended period of wake or that it took you a while to get to sleep. Most people need more than 5 1/2 hours of sleep each night to feel their best.

Well, it is typical of the last few months. having some insomnia and issues falling asleep. I even had to resort to day naps lately which have been wreaking havoc on my sleep. Before this current issue I was sleeping 8 hours a night on average and felt pretty rested. 5 1/2 hours definitely isn't enough to feel good.

robysue1 wrote: ↑

Sun May 26, 2024 10:55 am

2) How long did it take you to get to sleep? In particular, there's a lot of stuff going on between 2:35 and 3:25. Any chance you were awake and tossing and turning during that time period while fighting a low-level, but potentially irritating leak?

I think it took me about an hour to fall asleep. Yes, I saw the nonsense at those times, but I have been having insomnia issues of late. The few times I remember awakening, I didn't notice any leaks at all. However, I can't discount that it could be a low leak annoyed me at that time and I awoke to adjust the mask and simply don't remember it.

robysue1 wrote: ↑

Sun May 26, 2024 10:55 am

4) You have a lot of leaks. Whether they're a problem or not is an important question to answer. On the one hand, your leaks stay below the ResMed RedLine of 24 L/min. So they're not affecting the machine's ability to treat your apnea and accurately record hypopneas, OAs, CAs, etc. But on the other hand, those leaks might be repeatedly waking you up just enough to fiddle with the mask (in an attempt to fix them). Or it could be that you're waking up and fiddling with the mask to try to minimize the leaking for longer periods of time than you realize during the night. So what say you? Do you think you're waking up frequently to fiddle with the mask to fix leaks? Do you remember any extended periods of wake where you were fiddling with the mask to try to fix a nasty leak that just wouldn't stop? If so, then troubleshooting the leak problem is well worth it. But if you believe you are sleeping soundly through the leaks, these leaks are not large enough to adversely affect therapy and could be ignored.

I'm unsure if the leaks are causing me to arouse. I have recently been diagnosed with a few health issues that might be affecting my sleep. Currently, I'm leaning more toward the health issues as the culprit more than me fiddling with leaks. However, I could be wrong since this seemed to have started with huge leaks on the Air Touch F20. I do think my jaw drops when I fall asleep, so that is the likely culprit for the leaks. I'll have to see if things get better with the new mask.

I can tell you even with me sleeping less, I feel way better on CPAP than off CPAP. I had so many strange problems before getting on CPAP from heart palpitations, lightheadedness during the day, weird blood pressure changes from low to high, headaches, waking up gasping for air, hallucinations upon falling asleep or awakening, etc. Funny, I never felt tired. However, almost all these issues went away over time using the CPAP.

Thanks for the response and ideas!

vandownbytheriver wrote: ↑

Sun May 26, 2024 4:13 am

So stay off your back and/or let the pressure go higher... keep those leaks down. Looks like it wants you around 8cm base level... IMO.

Does this look like a leak rate issue or positional to you? I went to sleep on my back and woke up on right side. I think you may right about pressure needing to be raised if it looks positional. I saw 24ml leaks, but also some lower leaks when the OA and H's happened. Not too bad though for the night. Please note the time is not correct on the report. I need to + 1 hour my CPAP.

Here is latest report: https://sleephq.com/public/5df51740-fa2 ... cd2c2d3603

Thanks!

Movieman wrote: ↑

Tue May 28, 2024 11:15 am

vandownbytheriver wrote: ↑

Sun May 26, 2024 4:13 am

So stay off your back and/or let the pressure go higher... keep those leaks down. Looks like it wants you around 8cm base level... IMO.

Does this look like a leak rate issue or positional to you? I went to sleep on my back and woke up on right side. I think you may right about pressure needing to be raised if it looks positional. I saw 24ml leaks, but also some lower leaks when the OA and H's happened. Not too bad though for the night. Please note the time is not correct on the report. I need to + 1 hour my CPAP.

Here is latest report: https://sleephq.com/public/5df51740-fa2 ... cd2c2d3603

Thanks!

Uhhh... the link expired.

vandownbytheriver wrote: ↑

Wed May 29, 2024 10:09 pm

Uhhh... the link expired.

Oh! Hard to read then. Apologies. The original link was for May 27. The past couple of nights have been better though. I didn't upload last night to SleepHQ yet, but I have May 28 to compare.

See below:

May 27 Link - High leak rate (time off by an hour): https://sleephq.com/public/7acdc834-177 ... 929ac979e8

NOTE: May 27. First OA looks very long. Had mask issue and pulled it off to fix and the machine ran for a bit without me in it. Must have registered a big apnea.

May 28 link - Low Leak Rate (correct time): https://sleephq.com/public/29a036f4-742 ... af3d8e9ba5

Machine seems fairly accurate and Air Touch seems to have been the big culprit. Vitera is working much better. Still wondering if slight pressure bump might stop machine from maxing out and help leftover apnea/hypopneas/? I'll have to upload last night and see the results.

Thanks.

Still looks like it wants you around 8 or 9 base level. Or just leave it where it is... no biggie, you're doing great.

vandownbytheriver wrote: ↑

Thu May 30, 2024 9:59 pm

Still looks like it wants you around 8 or 9 base level. Or just leave it where it is... no biggie, you're doing great.

Sounds good. Thanks!