General protocol for self pressure adjustment – Comments?

[Captain_Midnight]

Hi folks.

Tomorrow I expect to receive my new Respironics A-Flex APAP, and I thought I’d run my pressure adjustment protocol by the experts. ( I did look through the morass of previous posts and couldn’t find such a protocol. It might be there, I just couldn’t locate it.)

As a background note, I’ve been using a Respironics CPAP w C-FLEX for the past 2 years, with reasonable success. My reasons for wanting the APAP are (1) determining just what my pressure “sweet spot” or therapeutic range might be, and (2) using the data generated by the machine as positive feedback to optimize my therapy on a continuous basis. It forever bugs me that my current machine only tells hours of compliance, and nothing about AHI etc.

. Self pressure adjustment protocol – Draft 1

1. First two or three nights, run APAP on CPAP mode at my current pressure (8 cm/H2O) in order to develop a baseline AHI.

2. For the 3 ensuing nights, run on APAP mode, setting the range at -1 and +1 from my titrated pressure (7-9 cm) and record results. If no improvement, try 6.5 – 9.5 cm range)

3. Using the data as a guide, adjust pressure accordingly (this is where my scheme starts to fade. I’m not sure how to proceed on a prudent pressure monitoring and modification path beyond this point.) Any and all suggestions and recommendations are welcome.


Thanks so much for your time and for sharing your wisdom.

Regards all -- Tom



.

[mindy]

Hi Tom,

Based on what I've read, I generally try to stay at one pressure range for a week or two. There are too many variables for a few nights to be definitive.

I've also noticed that as I slowly raise my lower pressure, my average pressure increases and 90% pressure increases ... but my AHI is going down and, most importantly, I'm feeling better.

I wouldn't plan too far ahead and look at the results before you make the second change... and so on.

Mindy

[GumbyCT]

I am by no means an expert in this or any other field. Expert simply means you've already made ALL the mistakes, right?
Well, I am still making my share of mistakes. So take this for what it is worth -

I didn't not see any plan in there to review your leak rate? Of course to do that YOU need to know your mask leak rate. My point is your therapy will not be as effective until you fix any leaks you have.

Please don't take this to mean that your mask rate AND leak rate MUST be identical. I do NOT believe that is even possible, except for unknown errors in the machine and/or software that make it appear they are identical. Just minimize the leaks you have.

I have seen many posts on here where the user appears to be right in their "sweet spot" so they begin to "prefect" it by looking for leaks which simply are no where to be found. To me, that is a very time consuming & unnecessary ordeal.

I am not sure if you should widen your window a bit to ensure you find the correct pressure w/o too many more events. But keeping an eye on the machine & software should clue you in if you are still having to many events.

Maybe include a reminder to note how YOU are feeling, how you slept, side or back, what you ate or drank?

Hopefully the many members who have much more insight than myself will weigh-in on their experience.

I will simply say, easy does it.

Good Luck,
GumbyCT
ps. keep in mind as your pressure increases so will your leak rate. Make sense? So don't go looking cuz it just ain't there.

[DreamStalker]

1. Get the software or at least set up a spreadsheet and collect 1 to 2 weeks efficacy data (leak rate, pressure setting, AHI, etc). Also assumes you already have a data capable machine.

2. Do whatever you have to do to properly control your leak rates before you try and make any adjustments to pressure(s). That means trialing different masks if neccessary so that you get a comfortable fit for the entire night of sleeping with minimal leaks. Confirm you are not leaking from your mouth while asleep. Finding the right mask interface is 80% to 90% of the difficulties.

3. Adjust your heated humidifier to work comfortably with your mask interface and bedroom ambient environment.

4. Once you have leaks and HH under control, you systematically adjust your pressure(s) up then down (1 cm at a time and collect data for 1 to 2 weeks between each change in pressure) without changing anything else and then plot your AHI and AI against the changes in pressure that you made (basically you do a sensitivity analysis of pressure vs AHI/AI). Patience is key to success in this phase. The plot will show you what pressure minimizes your AHI/AI. An APAP machine makes the tweaking easier and faster. Also, if you use Respironics machine/software, you can simplify the analysis with James Skinner's Encore Pro Analyzer software.

5. Then you periodically monitor to make sure your set up is optimized for minimum apnea/hypopnea events.

FORGOT TO ADD: As Bill pointed out in another thread, if you have other Sleep Disordered Breathing conditions besides OSA, you will need to consider the effects on those other conditions as you tweak your equipment to minimize AHI/AI.

[Captain_Midnight]

Thanks all!

DreamStalker, you said basically you do a sensitivity analysis of pressure vs AHI/AI, and I'm wondering what the significance of the AHI/AI ratio might be.

In other words, I was just going to plot pressure P vs RDI. If I plot vs the A+HI/AI ratio, this means that means that apneas are weighted differently from hypopneas; and I'm trying to figure out why this approach might be preferred simply to P v RDI

Again, I appreciate your response.

Regards all. - - Tom

[jskinner]

3. Using the data as a guide, adjust pressure accordingly (this is where my scheme starts to fade. I’m not sure how to proceed on a prudent pressure monitoring and modification path beyond this point.) Any and all suggestions and recommendations are welcome.

If it where me I would probably start out with a range of something like 7-10 or even 6-10 given that you are currently at 8cm. I'd run the machine for a week that way (as long as it was comfortable to do so) Checking the stats each day to see where in the range I was landing.

After that time is up you can compare the AHI at different pressures. (EPA can help you there if you want to automate it) Once you have an idea where your sweet spot is then you can narrow the range more and see how that goes.

If your happy with the results leave it at that or if you want you could then switch back to strait CPAP mode at the determine pressure. Remember that strait CPAP can give you the best therapy if you can tolerate the constant pressure otherwise find the tightest range that works for you.

The more expert users in the group can probably give you more ideas (or correct mine)

[rested gal]

2. Do whatever you have to do to properly control your leak rates before you try and make any adjustments to pressure(s). That means trialing different masks if neccessary so that you get a comfortable fit for the entire night of sleeping with minimal leaks. Confirm you are not leaking from your mouth while asleep. Finding the right mask interface is 80% to 90% of the difficulties.

3. Adjust your heated humidifier to work comfortably with your mask interface and bedroom ambient environment.

4. Once you have leaks and HH under control, you systematically adjust your pressure(s)

I like that advice from DreamStalker. It's essential that mask leaks (and mouth leaks if not wearing a Full Face mask) be absolutely well under control or your pressure and AHI data can be skewed.

If my prescribed pressure for "cpap" is 8 cm H2O, I'd set the autopap's minimum pressure at 7 and the maximum pressure at 15.

Using software (not just info from a machine's LCD window) is essential, imho, if you're going to tweak pressure settings.

[ozij]

HI s more sensitive to the change in the bottom pressure. AI is more sensitive to the top of the range. AHI is the total of them both.

In addition to Dreamstalkers excellent advice, I would also record and track the time spent in apnea - which your software reports.

O.

[Captain_Midnight]

Ozij, you said HI s more sensitive to the change in the bottom pressure. AI is more sensitive to the top of the range and I find this quite fascinating. This seems to mean that as PAP pressure rises, therapeutically hypopneas are treated at lower values than frank apneas. Is that correct?

I can't seem to search this out at Pub Med. Can you recommend an online source where I can read more?

Thanks much!

Tom

[ozij]

This is one case where I don't have a formal (study) source.

It's my personal expereince,knowledge gleaned from reading this forum for a long time, and also some common sense:

Think of a door you want to open and go through, and someone on the other side is leaning on it.

You try to go in like you would normally - obstruction. (Apnea)

You use some force to to push it open- you can now put you foot in the door - partial obstruction at lower pressure. (Hypopnea).

You use a lot of pressure, the person on the other side gives up, you go in through a wide open door.

With your bottom pressure too low, you'll be having more hypops than necessary. With the top too low, you'll be having more apneas.

O.

[rested gal]

This seems to mean that as PAP pressure rises, therapeutically hypopneas are treated at lower values than frank apneas. Is that correct?

I think it's the other way around. For example, in a sleep lab bipap titration (as I understand it) both pressures are raised together - 4/4, 5/5, 6/6, etc. - until apneas are eliminated. The lower pressure ("EPAP" for exhaling) is kept there while the titration continues raising what will be the IPAP pressure (for inhaling) until the remaining events (hypopneas, flow limitations, residual snores) are eliminated.

To me that means that in an autopap it would make sense to set the lower pressure at enough pressure to try to prevent all apneas, letting the higher pressures in the range handle the partial closures that produce hypopneas, flow limitations, and snores.

It always seemed odd to me, when I first thought about what pressure (low one or high one) handles complete apneas. Since "apnea" is the worst thing...least air flow coming through... it's intuitive to think, " Apneas are the worst, so it must take more pressure to prevent apneas than to prevent hypopneas."

But when you think about it this way... if only 7 cm keeps the throat from closing completely, you won't have an apnea. However, 7 cm might be letting the throat collapse somewhat. The partial collapse is an hypopnea.

It might take only 7 cm to prevent the full closure of a frank apnea, but might take 9 or 10 cms to keep the throat completely open...preventing even a partial closure. Preventing hypopneas.

[ozij]

To me that means that in an autopap it would make sense to set the lower pressure at enough pressure to try to prevent all apneas, letting the higher pressures in the range handle the partial closures that produce hypopneas, flow limitations, and snores.

I think you can't take the bipap titration as an example for setting up an APAP.

Suppose the pressure we set to eliminate most apneas would be EPAP on a bipap, and the bottom pressure on an APAP.

Nown on an APAP:
We rarely have 0 apneas. Apnea resoved the machine drops down to the level at which most apneas are resolved - regardless of whether the person is inhaling or exhaling. So basically on the APAP, you now have EPAP pressure, for inhale activitiy. And this is where hypops and all those other events start happening. So you have to raise the bottom pressure to keep them from happening.

IPAP sets a limit to how low the machine will go on inhale - and bipap titration assumes that further events occur on inhale.
Setting the bottom limit on an APAP to EPAP pressure (enough to eliminate apneas) is not enough, because the automatic machine doesn't switch to IPAP every time the person inhales. And those residual events - start happening at that EPAP equivalent bottom pressure.

By the way I find it hard to blieve that setting an EPAP minimum to "no apneas"means no apneas happen on inhale. I think it only means this is the lowest pressure reasonable for that person, and only on exhale. And then we start taking care of what happens on inhale. It is far easier for me to assume that snores and their ilk mostly happen on inhale.

And then of course there's that old discussion of "what is a hypopnea on a PSG, what if at all it on a machine's reprot, and what is a flow limitation" - I don't think we have to go into that because whatever we call them, they still are flow disturbances, occuring on inhale and needing to be taken care of.

O.

[DreamStalker]

Thanks all!

DreamStalker, you said basically you do a sensitivity analysis of pressure vs AHI/AI, and I'm wondering what the significance of the AHI/AI ratio might be.

In other words, I was just going to plot pressure P vs RDI. If I plot vs the A+HI/AI ratio, this means that means that apneas are weighted differently from hypopneas; and I'm trying to figure out why this approach might be preferred simply to P v RDI

Again, I appreciate your response.

Regards all. - - Tom

Sorry, I did not mean AHI/AI as a ratio ... I meant P vs both AHI and AI ... two curves superimposed on same chart.

[mindy]

Hi all,

I'll add one other small item to the stew, and, although I hate to raise this, it does speak to the issue of accuracy of our APAP machines vs PSG. Sleep doc told me that my M-series APAP is not as sensitive as PSG and will count some hypopneas as apneas.

When I started 3 months ago (today) I was rather obsess with the numbers. I've calmed down about it and now I don't think too much about how many of each but rather the total AHI, leaks and, most important, how I feel. The latter is a challenge because of numerous other health conditions but I do notice when things improve.

Mindy

[packer]

when I was starting DME was not around so-

I set the APAP at 8 to 15- put the aflex on 3- did my very best to not have leaks-
and just tried it for s few days- checking everyday- not just the numbers but how you feel- also- do you have a bed partner- their input is helpful also

then after a few days maybe raise your bottom a little - get it up a little closer to your 90%- top doesnt seem to matter much- its APAP right?
[my 90 is around 11]
I am no doctor- have no business giving advice!- just a old farm boy sort of way of making it work- which it does-- aflex is great- have my numbers down to consistent under 2 AHI- and feel better- aflex is great-

let the apap and aflex work - and read results- quit trying to do it perfect is what I am saying- its a great machine-- packer