BiPAP settings and false inspiratory triggering

[PeaceSleeper]

(TITLE UPDATED APRIL 23 TO MORE ACCURATELY REFLECT CONTENT)

Finally got hold of brand new M series Auto BiPAP.

Unit is set in bilevel with biflex, 9/4. Biflex is set at 2. (auto off)

Two puzzling behaviors from the machine.

1. Inhalation---it stops support pressure before I'm done inhaling. Sort of like having the air sucked out of your lungs 2/3 the way through an inhalation. Is it supposed to do this?

2. Exhalation--when I exhale, I usually have a one or two second post-exhalation pause. Well at the end of the my exhalation, the machine sometimes decides to do 2 (two) one second "bursts" of air---no kidding, and then stops doing it. Sometimes it will do 3 short bursts, then stops. I don't know if there is some backup program that is trying to stimulate breathing, or some other basic error I am making in setup.

Any help in solving these minor mysteries would be great, as I really, really like having the low expiratory pressure.

(And trying to use an Activa with this thing feels like I am part of a blacksmithing operating----the Activa is the bellows! Comfortgel seems to do much better.)

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CPAPopedia Keywords Contained In This Post (Click For Definition): bipap, activa, auto

[christinequilts]

A lot of what you're describing sounds like normal BiPAP behavior, though some may be a result of BiFlex settings. Do you know if BiFlex is turned on? None of my BiPAPs had that, so I'll leave that to someone who is more familiar with it on how to set. Basically BiFlex or, if BiFlex is turned off, Rise Time, is how quickly it switches from IPAP to EPAP. Too quickly can feel abrupt, choppy. BiFlex goes beyond what Rise Time does, and lets it drop below EPAP for just a fraction of a second to soften the difference even more.

You are the one leading the machine, its not leading you, but it is looking for any cues to switch from IPAP to EPAP or vice versa. The 'bursts' of air you feel at the end of exhalation is because it senses enough of a change in your air flow to think you are inhaling, but as soon as it realizes you aren't, it drops back. Same on inhale 'cutting out', you gave it enough of signal to make the change. Sometimes the changing in pressure can make some peoples breathing worse- some people can't even use Cflex or EPR on CPAPs because of the destabilizing effect it can have on breathing in a small percentage of people. It might be useful to set it in straight BiPAP mode and spend some time breathing normally so you can feel what it feel like and then throw it some curve balls, so you what it does when you do that too. A lot of people have problems in the beginning, especially if they think the machine is 'tripping them up', when in reality they its more they are 'tripping over themselves'.

As for the Activa, it sounds like you had it on too tightly. I used an Activa early on for a couple months with my BiPAP ST set at 12.5/7 with no problem, but whenever I pulled it out to use instead of my Swift or ComfortCurve, I had the same problem you did...it felt like someone was punching me in the bridge of my nose on every inhale/exhale cycle all night long. I'd put it away, wondering how I ever used it, until I knew I didn't have choice and needed to get use to it before switching to VPAP Adapt SV. When I finally took the time to get the straps adjusted loosely enough, there is no more 'punching' or bellowing, just a wonderful seal. The straps should be loose enough that they barely hold it on unless there is air flowing- the straps guide it and prevent it from blowing off your face completely, not holding it in place like other masks.

[DP]

Sounds like some of the settings are not right. You can talk with you DME about fixing this.

BTW, ResMed has just released an Auto-Bi-level machine called the Malibu. I have not used nor seen it yet, but I hear is uses some Adapt SV technology which means it may be easier to breathe on vs Respironics Auto-Bilevel. But again I do not know for sure. Just wanted to throw that out there.

[PeaceSleeper]

Christinequilts,

Thanks so much for the detailed reply---that gives me a good starting point. I think you are right---I had the mask too tight because it was also my first night using the Activa, though the auto-rise behavior occurred with my comfortgel as well--only after using the activa--so there is something to that.

It seems smart to start with biflex off, then progress from there since I can change the rise time. I'm traveling right now so don't have my card reader with me, so can't report on event control. I'm clearly throwing too many variables into the mix at once and expecting good results. I like the Activa from both a seal and comfort standpoint, but the bellows action will take some "training" on my part so it doesn't keep me awake. Narrowing the EPAP/IPAP range a bit should help that I'm guessing.

I'll get back on when I have more data to share.

Peace

[christinequilts]

Don't worry- even when my best friend started on a BiPAP after having heard me talk about it a lot, she called me in a panic because the machine was making her breath funny (pushing her around) & she could hear a loud noise when it switched from IPAP to EPAP (rise time set at 0). She even tried to get me to listen for the 'noise' over the phone

I wouldn't necessarily turn BiFlex off, but try it at 1 to start with. Alternatively, if you do turn it off, set the rise time to 3- that is equal to the default rise time on the original BiPAP from Respironics that didn't have all these extra adjustments. And once you get your Activa loose enough, it shouldn't 'bellow' really at all. One trick with it, or any air cushion mask, is to lay down with it on while hooked up to your machine, then undo the Velcro, letting it go out until it leaks, reVelcro just tight enough to prevent leaks. And don't forget to loosen the top straps on the Activa & play with the forehead angle thingy too.

[NightHawkeye]

PeaceSleeper,

You might also want to ensure that you have eliminated leaks - even small leaks. I had the same problem with my BiPAP-auto, and found that eliminating leaks was key to eliminating the problem.

Regards,
Bill

[Snoredog]

[quote="PeaceSleeper"]Finally got hold of brand new M series Auto BiPAP.

Unit is set in bilevel with biflex, 9/4. Biflex is set at 2. (auto off)

Two puzzling behaviors from the machine.

1. Inhalation---it stops support pressure before I'm done inhaling. Sort of like having the air sucked out of your lungs 2/3 the way through an inhalation. Is it supposed to do this?

2. Exhalation--when I exhale, I usually have a one or two second post-exhalation pause. Well at the end of the my exhalation, the machine sometimes decides to do 2 (two) one second "bursts" of air---no kidding, and then stops doing it. Sometimes it will do 3 short bursts, then stops. I don't know if there is some backup program that is trying to stimulate breathing, or some other basic error I am making in setup.

Any help in solving these minor mysteries would be great, as I really, really like having the low expiratory pressure.

(And trying to use an Activa with this thing feels like I am part of a blacksmithing operating----the Activa is the bellows! Comfortgel seems to do much better.)

[PeaceSleeper]

I am not understanding the last post.

If fixed pressure titration was at 9 cm, then the top end of bipap titration would likely be at or very close to 9 cm, no? I have had two fixed titrations and one bilevel titration. The fixed titrations resulted in two different recommendations from two different sleep labs. The first was 10 cm fixed, though they had titrated as high as 12 cm and found an unacceptable level of central apnea occurrence. That same lab also did a bilevel titration with IPAP 10 and EPAP 5 with what they called optimal results. The second lab did a fixed titration only and recommended 9 cm plus/minus 1 cm. I have monitored my fixed pressure levels from multiple auto mode titrations and the curve flattens at 8.5 cm with the lowest AHI at that point. (35 days of data) Above 8.5 cm, the AHI climbs fairly fast, I presume due to centrals.

When I asked the latest sleep doc for a script for a bilevel machine she wrote it for 9 IPAP and 5 EPAP. Unless the rise time is super slow, why would the top number increase, particularly since I have a bilevel titration showing it would not be appropriate?

As for the DME, he suggested going for a week in auto mode and see where the machine wanders with 10 IPAP, 4 EPAP, and support at 8 cm default---which of course is meaningless since support is at 6 cm to start with. That may be the right way to go though I have not been impressed with the M series auto mode operating in a wide range---only in a narrow. In a wide range it seems to end up at the max number which in my case may be a transition from obstructive to central apneas, where more pressure is not appropriate---but the machine can't tell as it cannot monitor respiratory effort only air flow.

Would greatly appreciate feedback and help understanding.

Cheerio!

[Snoredog]

[quote="PeaceSleeper"]I am not understanding the last post.

If fixed pressure titration was at 9 cm, then the top end of bipap titration would likely be at or very close to 9 cm, no? I have had two fixed titrations and one bilevel titration. The fixed titrations resulted in two different recommendations from two different sleep labs. The first was 10 cm fixed, though they had titrated as high as 12 cm and found an unacceptable level of central apnea occurrence. That same lab also did a bilevel titration with IPAP 10 and EPAP 5 with what they called optimal results. The second lab did a fixed titration only and recommended 9 cm plus/minus 1 cm. I have monitored my fixed pressure levels from multiple auto mode titrations and the curve flattens at 8.5 cm with the lowest AHI at that point. (35 days of data) Above 8.5 cm, the AHI climbs fairly fast, I presume due to centrals.

When I asked the latest sleep doc for a script for a bilevel machine she wrote it for 9 IPAP and 5 EPAP. Unless the rise time is super slow, why would the top number increase, particularly since I have a bilevel titration showing it would not be appropriate?

As for the DME, he suggested going for a week in auto mode and see where the machine wanders with 10 IPAP, 4 EPAP, and support at 8 cm default---which of course is meaningless since support is at 6 cm to start with. That may be the right way to go though I have not been impressed with the M series auto mode operating in a wide range---only in a narrow. In a wide range it seems to end up at the max number which in my case may be a transition from obstructive to central apneas, where more pressure is not appropriate---but the machine can't tell as it cannot monitor respiratory effort only air flow.

Would greatly appreciate feedback and help understanding.

Cheerio!

[PeaceSleeper]

Snoredog,

Thanks for the excellent graphic--makes sense that obstructive treatment occurs during exhalation since the airway should be well splinted with inspiratory pressure before exhalation occurs. I now understand your earlier comment and it suggests the first lab's bilevel titration of 10/5 may have been incorrect. I need to go find the PSG when I get home and look it over---currently traveling. My recollection is that there were mostly hypopneas on the first titration--the bilevel one. The second one, about 5 years later, which was constant pressure only, showed quite a few obstructives as well as hypos.

The machine's behavior I guess is still puzzling. I'm back using a comfortgel and am quite sure it has very minimal leakage. I can, while fully awake, take 2 or 3 normal breaths counted on a simple cycle of one-one thousand, two-one thousand or 2 seconds for inspiration. Then a 2 second expiration cycle, also counted mentally. The machine follows normally for 2 breaths, then on the third breath, the machine stops inhalation pressure at almost exactly one second, then starts what I will refer to as the "puff cycle", where it provides inhalation pressure for about 1 second, then exhalation pressure for 1 second, then immediately back to 1 second of inhalation pressure, then exhalation pressure for 1 second. It may do this little "puff" dance for 2 cycles, sometimes up to 4 cycles. This is with no inspiratory/expiratory input from me---I'm holding my breath observing what it is doing through all of this---which I presume tells the machine an obstruction is occurring so it needs to increase pressure, when that fails--it sees no flow, it backs off. From what you've said, I suppose it is possible even while fully awake to create subconsciously an expiratory event that the machine interprets as an apnea and the only option it has since I'm not in auto mode, is to turn on full inspiratory pressure since it cannot increment EPAP.

It sounds like the DME's original suggestion of running in Auto mode initially was the correct one. Maybe the machine will titrate me up to a near CPAP state. As for using just straight CPAP---perhaps true, but aerophagia was so bad that I could not be compliant after 3.5 to 4 hours so that is not a long term option imho. Also, even with the weird behavior, my AHI score on the first night went down so it appears something is working better. I haven't been able to collect data for the last 2 nights due to travel.

I do appreciate the education and comments.

[PeaceSleeper]

I will get some data posted here in the next day or two. I realize without it this is going to be a frustrating discussion.

[dsm]

As far as I can see, that epap setting of 4 is just not right. The others posts have covered that point well. Can you try 9/6 ?.

Snores graphic is a very good reference & hopefully explains why 4 is a no no.

A gap of 5 between ipap & epep at such a low titration is very big. That alone will affect an activa mask. Reduce that gap to 3 & the mask is likely to behave normally providing you have the straps 'soft'.

Bipaps are known to flip ipap to epap early if there are any problems NHK highlights the leaks issue.

Also if you are a shallow breather of have constant nasal congestion or sinus problems you may notice early flipping problems. Need to look at ways to keep nose clear (nasonex etc:).

Good luck

DSM

[PeaceSleeper]

Thank you DSM for your comments---very interesting. And yes I have had life-long sinus and congestion issues, so that will be a challenge. However with only a couple of nights under the belt I am sleeping better, longer, and feel better in the morning so I feel I am on the right path. Even on auto last night for 2 hours, I continued to experience the strange one-second bursts of air after exhaling---very annoying, though not as noticeable when IPAP and EPAP are close together---sort of CPAP-like.

For Snoredog---your question about hypopneas was spot on. My study showed almost all hypopneas---some very long ones, but no obstructive apneas. Most during REM, 59/hr. I had a total of 3 centrals during 312 minutes of sleep and fewer hypopneas for sure outside of REM. I don't know if there is any value of posting any of that or not.

Here is my first 2 hours last night (I know---not enough data to really conclude anything.....but maybe you can tell me why I'm getting the weird one second bursts of IPAP level air after exhaling.) while in auto bipap mode with these settings:
IPAP 10 cm
EPAP 5.5 cm
PSMax 3 cm
Biflex 2

It produced the following result:


And here is the detail:


I will plan tonight to raise EPAP to about 6 cm, maybe IPAP to 10.5 cm, since I am still having a fair number of hypopneas. However, I'm a little concerned that those OAs are really CAs since they come later in my little two hour window and at higher pressure.

Thoughts? And thanks!

[rested gal]

PeaceSleeper, that chart looks messed up...like none of mine. The doubles of the red IPAP line and doubles of the blue EPAP line are not the way it should be showing. Those should be single lines -- one single red line tracking IPAP pressure used and a single blue line tracking the EPAP pressure.

Occasionally I've had "double" lines like that show up in just a small section of one of my graphs, but nothing like all the way through, as they were in the short session you posted. Are you getting double lines like that on your other downloads?

If you don't mind, would you send me a PDF of your most recent download? I'll PM you my email address.

[Snoredog]

You need to IGNORE that 90% found pressure, it found those pressures because it had no other pressure finding to give (it won't refuse to report a 90% pressure).

For Snoredog---your question about hypopneas was spot on. My study showed almost all hypopneas---some very long ones, but no obstructive apneas.

You have to ask yourself: What are all those OA's I'm seeing above on that EncorePro report if my PSG showed I had zero? LOL.

those 3ea OA's seen at the beginning of your session... wouldn't surprise me if those were not onset CA's being scored as obstructive.

I'd go back down to 7/5 you have a zero AHI=0.0 there

(only kidding but your AHI is actually better there hehehe). But you have to understand that the machine "scores" events differently than a human being watching 12 channels on a EEG. They use specifically 50% reduction in flow vs. the machine's algorithm of 40%. For OA's, the machine may use 75-80% reduction in flow to consider an event an OA instead of complete occlusion which is what the lab would use.

Right now the problem as I see it: has more to do with the incorrect machine settings than anything. The problem is your IPAP and EPAP window isn't large enough for the machine to respond to anything, might as well just be in bilevel mode using fixed settings, in fact I bet your AHI would be better.

With those settings, first thing it is going to do is maintain that 2cm PS delta (pressure differential between IPAP and EPAP pressures), which is why it may be showing 9/7 as 90% pressure. Those 90% pressure findings are what the machine had to give you because of how limits are set. It won't refuse to give you a 90% pressure even if it is wrong.

Your 90% pressure finding is leaving you with a AHI=15.6, I wouldn't want to write home about that one.

Because of the narrow settings (i.e. limits set), EPAP cannot go any higher than 8cm because of the limit established for IPAP at 10cm. With the 2cm minimum delta always being maintained, EPAP will stop at 8cm.

My suggestion (with centrals being suspect above 9cm): Set or bump IPAP up 12cm, set PS=3, that will allow EPAP to come up to 9cm if needed and not trigger any CA's. Set your EPAP Minimum to the pressure that is comfortable for you to breathe at (I suggest 5cm or 6cm), but if you set it too high then IPAP won't be able to drop down (again because of the 2cm minimum PS delta that is always maintained).

IPAP Max=12cm
EPAP Min=6cm
PS=3

With those settings there, machine will start at 6cm EPAP pressure, IPAP will be at 8cm. On those 3 OA's seen, EPAP would have moved up by 1cm to 7cm (pushing IPAP to 9cm), over 5 minutes it would have moved up again by 1cm to 8cm (again pushing up IPAP to 10cm), another 5 minutes if those OA's were still there it would have increased EPAP to 9cm, IPAP would be pushed up to 11cm. Once EPAP got to 8cm, things change, it would kick in another part of the algorithm where it would need then to see a hypopnea and apnea together to respond. It would establish a NRAH threashold, but your limits would prevent that from ever being exercised. So if it did see the hypopnea it would have increased IPAP on up to the Max of 12cm, increasing the spread between IPAP and EPAP from 2cm to 3cm. With the new limits above, the maximum IPAP pressure that would be seen is 12cm. At the same time the Maximum EPAP that could be seen is 10cm (even if it was misreading and scoring CA's as OA's). So here is where a short PS setting comes in handy, that is lowering the pressure as events are eliminated, EPAP will begin to drop, as it goes down from 10cm to 9cm to 8cm, it hits the maximum PS=3 setting, so now if events remain calm, it will begin to pull down IPAP pressure (because you are at the PS=3 delta maximum spread). So it can go on down bringing IPAP with it. Set PS setting too high it will remain at higher pressures longer than it would if they were lower. This part requires a bit of common sense, if you were at 20cm pressure, I'd yeah man put PS=8 because your EPAP would still be at 12cm. But here you are only talking 12cm pressure tops, then that is only on IPAP not EPAP. EPAP is the one that maintains the patent airway. If you limit how high it can go, you limit its ability to splint your airway open. So if you are going to do that, you might as well set a lower fixed pressure and let those events go.

At this point you need to experiment within the constraints you are faced with, I think if you get your settings down correctly you'll find those pressures are very easy to breathe against and still get good treatment.

I'd get the pressure(s) set correct, Biflex at lowest setting or off, once pressures are established to get the AHI=<5, then increase Biflex util it is more comfortable. At those pressures, I don't see you using a higher Biflex setting of 2.