using Auto to determine bi-level settings?

Hey, all.

Please pardon the longish post. There's some background below, then a question, and then a bit more info that I thought I should mention. I'm hoping some of you who are way more knowledgeable than I am can share your thoughts or make a suggestion.

I've been using my new Respironics classic BiPAP Auto for over a month now, almost exclusively in the bi-level mode with BiFlex at 2. Night one I started out in Auto, but it drove me crazy--well, what really did it was the Activa nasal mask. (I know some folks love it, but after ten-plus years on CPAP with a "normal" nasal mask, a Mirage Ultra, I can't deal with the Activa.)

After reading some recent posts (regarding pressure and other BiPAPian topics), I decided to try the Auto setting again Sunday night.

First, some background. With 35 nights of data in, here are my settings and averages:

• titration settings from 9-24-2008: 14 IPAP, 11 EPAP.
  pressure settings, first 10 days -- 14 IPAP, 11 EPAP
  pressure settings, next 24 days -- 14.5 IPAP, 11 EPAP
  avg AI -- 2.7
  avg HI -- 2.9
  avg AHI -- 5.6
  avg usage per day -- 6 h 57 m 33 s
  avg time in apnea per day -- 4 m 21 s
  avg VS -- 0.1
  avg 90% leak -- 54.6
  avg leak -- 45.2

So Sunday night I tried the Auto with BiFlex setting again, with max at 17 and min at 11 and a max PS of 5. Here's a breakdown of the data from that night:

• 73% of the IPAP time was spent at 17cm, with 0.4 FL, 0.0 VS, o.o NR, and 8.9 H. So basically, for that 4.5 hour chunk of time, my HI was 2.0.
  
  35% of the EPAP time was spent at 14 cm, with 0.9 FL, 0.0 VS, 0.0 NR, and 1.4 OA--that's an AI of 0.64.
  11% of the EPAP time was spent at 11 cm, with 4.3 FL, 0.0 VS, 0.0 NR, and 0.0 OA.
  (The other EPAP times had higher OA figures. . . .)
  
  avg leak for that one Auto night -- 51.0

First, I decided I just wasn't ready for Auto anything. Either that, or the Respironics algorithms don't particularly suit me.

Second, I decided to try something different last night rather than going back to 14.5 / 11. Using the data from the Night of the Auto, I set the machine at 17 cm IPAP and 14 cm EPAP. I also changed the BiFlex setting to 1.

The data from last night? Er, yes, the data. . . . Well, if I'd remembered to put the SmartCard back in the machine, I'd have some numbers to share. I think I got around 7 or 7.5 hours of sleep; the higher pressure didn't bother me, and I liked the BiFlex 1 setting better than the 2 setting. I don't think I felt as energetic today, but I'm not positive that isn't just because I've had a minor cold.

So tonight, I'm thinking of trying 17 / 14 again. That, or go back to 14.5 / 11 again, or 15 / 11, and see what happens.

The question: Anyone have any thoughts or suggestions? Is it crazy to use the best settings from one night of Auto as the bi-level settings for future nights, even if it's 3 cm higher for both IPAP and EPAP than what my titration study recommened?

I've got an appointment with my sleep doctor on Thursday, so I'm planning on mentioning this and all kinds of other stuff to him. (I wonder what he'll have to say about the connection between OSA and Central Serous Retinopathy . . . and about my taking charge of my therapy with the help of the cpaptalk folks.)

One other thing I should mention. During my titration study, I had an overall sleep efficiency of 68.5%, but in the three hours spent at 14 / 11, efficiency was 94.7%. Throughout the night, I had 147 centrals and 107 hypopneas--from what I can tell, I had no obstructives. During the 3 hours at 14 / 11, my AHI was 2.1. Which may be why they decided a BiLevel device was the way to go with my treatment.

I think some of the events at my titration study were brought on by the constant changes in pressure. I think the same may be true of my Auto numbers from Sunday night. I've also noted some apneas occurring about 90 minutes into each night of sleep, which I think Rested Gal has pointed out was when REM kicks in, and also just before I wake in the morning, and when I go back to sleep after waking for whatever reason (which sometimes doesn't happen, but when it does, is usually just once a night).

Anyway . . . any ideas would be appreciated. I figure after a month, I might want to do something different, and I really respect the advice offered here.

Thanks,

Nath

One night's data on an auto really doesn't tell you diddley-squat. Give the pressure setting change a full week then check your averages.The first two nights of a change generally don't tell me diddley-squat. They may be drastically better or drastically worse than the prior settings but then the next 4-5 nights averaged out w/the first 2-3 give me a true picture and seem to hold true if I stay at that change..

My opinion:

Pay special attention to which pressure takes care of which event:


From the graph above you learn that IPAP pressure takes care of Hypopnea.
EPAP Pressure takes care of Obstructive apnea and snore.

Think of IPAP as being a little hammer, EPAP as being the big hammer, apply a little logic to it,

While it is not always the case, think of the events as going left to right below and increasing in severity as you go to the right:

Silent Flow Limitation->Flow Limitation -> Hypopnea->Snore->Apnea

With some people you work backwards starting with EPAP to eliminate the apnea, eliminate the apnea the residual effect may be
a Hypopnea apply enough pressure you may still have residual Flow Limitation. Snoring can show up where it wants but many
times it shows up right before the apnea. So after eliminating the Apnea you may still have some residual snore, as you increase EPAP pressure to eliminate the snore you can still have residual Hypopnea and Flow Limitation. As the graph shows, those residual events are taken care of by higher IPAP pressure. So EPAP pressure stops increasing and IPAP pressure rises higher.

So in the above, you would

-use EPAP pressure with a high enough value to eliminate the Obstructive Apnea (OA) and snore.
-use IPAP pressure to eliminate the residual events.

What does it mean if IPAP pressure increased to 17 and EPAP remained much lower for a greater PS? It may mean Max. Pressure Support setting is to high. Goes back to the little big hammer theory, apply higher IPAP pressure to eliminate the residual events, if it does not eliminate it, you need a bigger hammer, in which you bump up EPAP where a lower IPAP pressure can be used.

Now another theory with UARS is there is another flow limitation lighter than the ones that show up on your report called silent Flow Limitation, you cannot see it on your machine or outside the lab, but the theory is these silent residual flow limitations are caused by resistive breathing found in the upper airway such as in the nose. This is known as UARS or Upper Airway Resistance Syndrome. A few theorist suggest these silent flow limitations are the cause of what were once consider Spontaneous arousals, thought to disrupt your sleep architecture to the point of leaving you with excessive daytime fatigue (aka. Big Secret).

So, after looking at your numbers, I find the AI=2.7 or 3 on average per hour (residual). The pressure that takes care of those
are EPAP. Your EPAP Min appears to be at 11 cm. I would increase it to 12 cm. That should lower that AI from 2.7 to 1 or less.

Next, you don't know WHAT HI will do after you increase EPAP by 1 cm. It could take the need of IPAP avg. working pressure from 17 down to 12 too, you just don't know. So if you want to give the machine the range it needs to automatically find you a new 90% IPAP pressure after making that change, then give the machine the room it needs to work.

Then it all depends on HOW you like tolerating that 17 cm IPAP pressure? Does it appear to be fine or does it appear to be too high?

If it appears higher than you want it, increasing EPAP should result in a lower IPAP being needed. If you want to reduce the high IPAP pressure seen you use a lower PS=x setting. You are currently using 5 with existing EPAP pressure. If you used PS=4 IPAP would increase EPAP pressure once the spread between EPAP and working IPAP reached 4 cm (right now that is happening when you reach 5 cm separation).

So from what I have seen of your numbers above, you ignore HI for time being, concentrate getting AI and Snore down, then HI and FL. So I would try:

EPAP Min=12
IPAP Max=20
PS=4 (you can use your current 5 if you don't mind the higher IPAP seen)
Flex=1 (use what feels the most natural for your particular breathing)

You should easily be able to see the effects of changing your settings on Encore reports. For example; if you set PS=3 then IPAP will never get any farther apart from EPAP more than 3 cm. If you set PS=4, they will never get farther than 4 cm.

If you want to use pressure to maintain or eliminate UARS (it would only be based upon how you feel as you cannot see those microarousals) you then would have to use fixed bi-level settings, you cannot use the Auto mode. In that case you would take your 90% pressures seen, leave EPAP set where it eliminates the obstructive apnea, then keep padding IPAP not exceeding 10 cm from EPAP. If you get lucky you may resolve those spontaneous arousals if they were there in the first place.

Slinky wrote:One night's data on an auto really doesn't tell you diddley-squat. Give the pressure setting change a full week then check your averages.

That makes sense, Slinky. I was just pretty disgusted with the full numbers from using Auto that night--an AHI of 12.1 (AI 2.9, HI 9.2), and that's what made me try the 17 / 14 setting last night.

But you're right--a week with Auto might tell me something different. It might even turn out that Auto makes sense for me--though I really think the pressure changes wreak havoc with my AHI.

At least I have the card in the machine tonight!

By the way, "diddley-squat" is an expression my father likes to use. It made me laugh to read it in your post, too.

Thanks,

nath

Snoredog wrote:Pay special attention to which pressure takes care of which event: From the graph above you learn that IPAP pressure takes care of Hypopnea. EPAP Pressure takes care of Obstructive apnea and snore.

Thanks for the response, Snoredog. Actually, I think it was your post of this graph in a recent thread that made me try the Auto setting again.

While it is not always the case, think of the events as going left to right below and increasing in severity as you go to the right:

Silent Flow Limitation->Flow Limitation -> Hypopnea->Snore->Apnea
[. . .]
Now another theory with UARS is there is another flow limitation lighter than the ones that show up on your report called silent Flow Limitation, you cannot see it on your machine or outside the lab, but the theory is these silent residual flow limitations are caused by resistive breathing found in the upper airway such as in the nose. This is known as UARS or Upper Airway Resistance Syndrome. A few theorist suggest these silent flow limitations are the cause of what were once consider Spontaneous arousals, thought to disrupt your sleep architecture to the point of leaving you with excessive daytime fatigue (aka. Big Secret).

I'd wondered what Flow Limitations I'd see using Auto since they don't show up in the BiLevel setting. Oddly enough, I think I've had just three Vibratory Snores over the last month-plus, so my current EPAP seems to be working for that. But the FL and SFLs are something else to deal with. I'll definitely ask the sleep doctor about this on Thursday; I don't remember any mention of silent flow limitations in the big report, but it'll be interesting to hear what he has to say.

Your EPAP Min appears to be at 11 cm. I would increase it to 12 cm. That should lower that AI from 2.7 to 1 or less.

That sounds wise, whether I'm using Auto or BiLevel.

Then it all depends on HOW you like tolerating that 17 cm IPAP pressure? Does it appear to be fine or does it appear to be too high?

17 cm didn't seem to bother me. A bit higher would probably be okay, too, if I go with Auto.

So from what I have seen of your numbers above, you ignore HI for time being, concentrate getting AI and Snore down, then HI and FL. So I would try:

• EPAP Min=12
  IPAP Max=20
  PS=4 (you can use your current 5 if you don't mind the higher IPAP seen)

Makes sense. I think I just need to decide if I want to go with the Auto, or stick with bi-level, especially given what you write here:

If you want to use pressure to maintain or eliminate UARS (it would only be based upon how you feel as you cannot see those microarousals) you then would have to use fixed bi-level settings, you cannot use the Auto mode.

Whatever I do, I'll give it a few days, as Slinky suggested. I usually do things slowly anyway, as you can guess from my moving my IPAP up 0.5 cm after ten days, and leaving it there for the next three weeks.

Thanks again, Snoredog!

Does Snoredog have a pointer to further info about the curves?
I still can't figure it out how EPAP affects snoring (and apnea) and I'd be very interested in the
mechanism. I might give me a whole new picture of the events.

Just out of curiosity, can EPAP be set higher than IPAP and are there (even theoretically)
situations, where that kind of setting could be useful?

turbosnore wrote:Just out of curiosity, can EPAP be set higher than IPAP and are there (even theoretically)
situations, where that kind of setting could be useful?

EPAP (the exhale pressure) can never be set higher than IPAP (the inhale pressure.)

EPAP can be set at the same pressure as IPAP (example: EPAP 12, IPAP 12) -- in which case the machine would work as if it were just a plain cpap machine...at one steady pressure of 12 for both exhaling and inhaling.

With the BiPAP Auto, the operating mode would have to be set to bilevel only (not "auto bilevel") if a person wanted to set EPAP and IPAP to the same pressure.

Ah, NightJaw!!! Remember to put the card in!

I guess I need to explain why I find that so funny. Most of my xPAP experience has been w/the Resmeds. They work a little differently. You don't put the card in the device UNTIL you want to do a download instead of having to leave it in the device to collect the data.

But when I added the S8 ResLink to my Resmed, the ResLink works like the Respironics. That doggone card has to be in the device when it is used to collect the data. Of course, my habit by the time I got around to adding the ResLink was to NOT keep the card in the device, to only insert it when I wanted to do a download.

So guess WHO has cheated herself outta the night's full data by NOT remembering to put the darn data card back in the ResLink before I use my VPAP??? And, yeah. On MORE than one occasion!! Grrrrrr. Spend all that money to get the extra data and then FORGET to put that little ole card back in the device! Snort! This ole broad is NOT the brightest candle on the cake at times!!

Slinky wrote:So guess WHO has cheated herself outta the night's full data by NOT remembering to put the darn data card back in the ResLink before I use my VPAP??? And, yeah. On MORE than one occasion!!

Now, that would be confusing--getting used to one thing and then . . . yep. Be thankful it wasn't a timecard!

But don't feel bad, Slinky: it's happened to me twice so far. Maybe two nights ago I could attribute it to being more focused on the pressure settings rather than the data. Or I could just attribute it to being thirteen times older than my son, who'll be four in a month. (Poor kid! Along with sleep apnea, he's my main excuse for forgetting or goofing up.)

Well, last night I had the card in the machine. I wound up using it in the bi-level setting at 15 IP / 12 EP. AI was down to 0.7, and HI was 2.7. I'm planning on leaving it there for the next week to see what happens. I've had only three nights with a lower AI, so pushing the EP up a cm helped, I'm thinking.

Time will tell.

Time, too, to wake my son, who's sleeping late today for some reason. Maybe he's storing up energy for the 3-6 inches of snow we're supposed to get today. . . .

nath

Er, uh, time card?? I had trouble w/those too. Supervisor was never happy about it. So it worked out real well when I switched from clerk to rural letter carrier. No more time cards. We got paid by the evaluated day regardless how many hours we worked. Not too many days I worked under my evaluated hours. *sigh* Especially in the winter!

Stuff that snow bit! We got a good bit here. Not bad. But I'm reee-tired. I haven't even stuck my nose out the door to get the mail! I'm curling up in front of the fireplace w/a roaring blaze, a good book (actually an old one I am re-reading after 15 years or so) and occasionally I look out the window at the snow.

turbosnore wrote:Does Snoredog have a pointer to further info about the curves?
I still can't figure it out how EPAP affects snoring (and apnea) and I'd be very interested in the
mechanism.

Basically, EPAP (Snoredog's "big hammer") does the big heavy work. It's what keeps the airways open--which means it's the pressure setting that keeps apneas at bay. The IPAP (Snoredog's "little hammer") takes care of the smaller events, the hypopneas.

Here in Wisconsin--and there in Finland--it might help to think of EPAP as the big snowplow that comes along to clear the roads, the main traffic arteries. Then IPAP might then be the shovels and small snowblowers that people use to clear the snow from their driveways--and the snow that the plow dumped in front of their driveways.

(What can I say? It's snowing here. Soon, I'll be shoveling and snow-raking. Metaphor, metaphor. . . .)

nath