Varying AHI Readings on BiPap Auto SV Advanced

[JohnBFisher]

... Central apnea was observed, which is why I am on this particular machine, but the software is showing only about 1 per night now. ...

Others are doing a good job with most of the rest of your post, so I thought I would tackle this one sentence.

As you may know, I suffer from severe central sleep apnea. So, please understand that I am not a medical professional. I am just another person trying to struggle to find effective therapy.

Though you now only see one or two central apneas now, if you did not have this machine the number would probably be quite a bit higher. Why? The Auto SV unit is an adaptive servo-ventilator (ASV). This type of therapy, initially pioneered by Resmed, helps break the cycle that causes central apneas. Essentially, for whatever reason, your body does not always breathe as it should. You might either occassionally hyperventilate - just enough to blow of excess CO2 - or you might hypoventilate - slow down your breathing to the point excess CO2 builds up. The problem with other is that the precipitates a repeating cycle. When the body fails to properly ventilate to purge the CO2, an excess amount builds up. This is the undershoot side of the cycle. Eventually your body kicks in and triggers a slight hyperventilation. This tends to blow off too much CO2. This is the overshoot side of the cycle. The drive to breathe decreases. A central apnea occurs. The CO2 builds up. The body kicks in and triggers hyperventilation. Round and round and round you go.

If you were prescribed an ASV machine - and your insurance paid for it - I can guarantee you had severe enough central sleep apnea during your sleep study. These units a VERY expensive. You probably had over 5 central apneas per hour for the insurance company to approve the purchase. The good news is that you clearly are getting effective therapy with your ASV unit for the central sleep apnea.

So, now the doctor needs to work with you and your machine to get the obstructive side of the equation under control.

[JIMCHI]

I increased my EPAP Max to 10 last night while keeping the EPAP Min at 8. My AHI is still high- 13. I just have no clue what to do now.

[Banned]

Here is what I would try (The usual IANAD disclaimers apply): Set your EPAP max 2 cm higher than your EPAP min, for starters. If this makes an improvement, try 3 cm. Stop if this aggravates your central apnea issues. You might also increase your max pressure slightly, if you find you are improving, but coming close to your max pressure.

As an example, on my ASV advanced, my EPAP min is 8 cm and EPAP max is 15 cm. This accommodates the significant changes I see in my therapy from day to day. This was the original prescription setting (the rest is in my signature), and I have not had to touch the settings in 9 months.

You need to listen to this guy.

[JIMCHI]

I thought I did follow his advice. I increased my EPAP Max to 2 more (10) than my EPAP Min (8). I will try tonight with a min of 8 and a max of 12.

[Pugsy]

I thought I did follow his advice. I increased my EPAP Max to 2 more (10) than my EPAP Min (8). I will try tonight with a min of 8 and a max of 12.

One night might not give a clear indicator especially with someone who reports a wide variation in AHI from night to night already. That said, probably wouldn't hurt to try your next step. Just remember one night doesn't a trend make.

[-SWS]

EPAP 6 - AHI 13 (and I felt just awful the next day)
EPAP 7 - AHI's 14, 4, 7, 13, 10, 9, 15, 9
EPAP 8 - AHI's 5, 4, 11, 13, 9, 8, 11, 6, 8, 11, 16, 7, 9, 12, 5, 16
EPAP 9 - AHI's 10, 14
EPAP 10- AHI's 6, 10, 12, 8, 7, 11, 14, 11, 13, 10, 10, 11
EPAP 11 - AHI's 10, 12, 9

Well, moving EPAP around clearly isn't solving your problem. That might be because standard BiLevel titration protocol calls for IPAP to be increased in response to hypopneas. If fixed-EPAP 7 through fixed-EPAP 11 didn't make a dent in your problem, then I personally doubt allowing EPAP to automatically wander within those same EPAP bounds will solve your hypopnea problem either...

Looking at your graph below, we can see your excessive residual events are almost ALL hypopneas. And since standard BiLevel titration protocol wants to see IPAP increased to address residual hypopneas, I think I would be more interested in experimentally increasing PS min if it were me.

The good news is that you clearly are getting effective therapy with your ASV unit for the central sleep apnea.

So, now the doctor needs to work with you and your machine to get the obstructive side of the equation under control.

Since those hypopneas are undifferentiated, I don't think we can safely assume they're either obstructive or central. If they were obstructive, moving EPAP up might have better stented them; if they're central moving IPAP up would better ventilate those since stenting with EPAP is the wrong thing to do in that case. At least titration protocol calls for IPAP increases in EITHER hypopnea case...



RESIDUAL HYPOPNEAS:

[OutaSync]

Thanks, -SWS. I was hoping that you would come along and help him.

[-SWS]

Thanks, -SWS. I was hoping that you would come along and help him.

Well, I'm hoping my comments are converted to questions for the doctor during this essential visit:

I see my doctor next week.

Great! At this point your medical team are the ones who should be helping you with specific settings IMHO. In this thread you have mentioned almost no details about how prominent your central component was compared to your obstructive component during PSG diagnosis and followup titration. Additionally, we are not YET apprised of most of these current machine settings while you solicit suggested changes in this thread: a) rate, b) rise time, c) inspiratory time, d) EPAP min, e) EPAP max, f) PS min, g) PS max, h) Max pressure.

That's not to say people should quit sharing their ideas about possible settings. But I think far more details are warranted if you want the best possible input here. In any event, good luck!

[Banned]

Thanks, -SWS. I was hoping that you would come along and help him.

Nice call, SWS.

[JIMCHI]

Wow ! You all are wonderful to take an interest in my problems. I have had 2 sleep studies. In the first one, untreated I had 22 obstructive apneas, 13 central apneas (the longest was 20 seconds), and 11 hyponeas during 3.5 hrs of sleep. AHI was 13, REM AHI was 23. I was then started on a bi-pap machine at a pressure of 10/6. AHI was 13 with still a few centrals. Pressure was increased to 12/8 and AHI went to 38. A backup rate of 10 was added and AHI went down to 3.6, with a couple of centrals. So I was put on a bipap machine with 12/8. That pressure was too much for me and I was unable to sleep with it.

I then had another sleep study, this time with a VPAP. My AHI went to zero with no centrals noted when (the report says) "EEP was increased from 5 to 6 and IEP ranged from 9 to 16". So I was then put on a Resmed VPAP Adapt SV machine with an EEP of 6. But a few nights at home with that setting and I was somewhat exhausted the next day. DME provider then increased EEP to 8 and that is where I have been for 3 years, feeling OK but not great - but 75% better than I ever felt without any treatment.

Six weeks ago my Resmed machine was replaced with a Respironics BiPap Auto SV Advanced. EPAP was kept at 8. This machine apparently provides more data than the Resmed machine did and after a week the DME downloaded data and it showed I was having an average AHI of 9.5 Daily data showed a wide AHI range from 5 to 14 with most activity being hyponeas. Only 1 or 2 centrals were noted per night. The DME said that 9.5 was fair, but that the target AHI is 5 or less. So this is what started me on this quest to try and find the right EPAP. I purchased the Encore Reader software. But at no matter what setting I choose, over a period of days my AHI varies widely (as I listed in a previous message above).

Here are the settings on my machine as of tonight. I increased the EPAP maximum to 12 at someone's recommendation here and will try that tonight.
Pres Max 18
EPAP Min 8
EPAP Max 12
PS Min 3
PS Max 7
BPM Auto
Flex 3
Ramp 0
Apnea setup 0
Patient setup 0

[-SWS]

I see my doctor next week. I guess he could order another sleep study, but that would seem a waste as a sleep study is just a snapshot of one night. I could have an AHI of 4 at a EPAP of 8 on the night of the study, only to have a 16 the next night.

Bear in mind that Respironics claims your BiPAP autoSV Advanced can be set up to accommodate variability:
http://bipapautosvadvanced.respironics. ... otocol.pdf

It sounds like your DME originally set your machine up to match your Resmed Adapt SV settings---with the objective of garnering more detailed data. If it were me, I think I'd consider asking for an in-lab titration that adheres to the above protocol. There's a chance the machine will treat your variability well once they get it set up correctly.

And timbalionguy is right that your new machine offers titration features your previous-generation ASV machine didn't have: accommodating both obstructive and central variability is part of this machine's design premise. I look forward to hearing additional comments and opinions from others. Good luck.

[JIMCHI]

Tried last night with increasing EPAP Max to 12 (keeping EPAP min at and got an AHI of 14. Woke up a couple of times as with max pressure set so high I had some leaks, although my Encore report shows no large leaks and average leak of 42.3

I hate to have to go through yet another sleep study for titration. As my results are so random, the information captured from one night becomes insignificant; my chances of having an AHI of 5 are about as great as having one of 16.

[Banned]

..we can see your excessive residual events are almost ALL hypopneas. And since standard BiLevel titration protocol wants to see IPAP increased to address residual hypopneas, I think I would be more interested in experimentally increasing PS min if it were me.

Hey Guy,

As SWS suggested, you may be digging in the wrong pile.
Please review SWS's 'suggestion' to increase PS Min to mitigate the excessive hypopneas that is driving up your AHI.
You can start to help yourself by increasing PS Min to 4.

Your EPAP min 8 and EPAP max 12 settings are probably ok, as is.

Also, I would disengage Flex (set Flex to 0). Flex maybe messing with you, too.

[JIMCHI]

Thanks. I will make those changes tonight.

[JIMCHI]

I made the changes suggested. Still has an AHI of 9 last night. Is there some possibility that the machine is just incapable of fully treating my condition?