Getting "over inflated"

[den942]

Several times I have woke up unable to exhale because my lungs were full but the machine was
trying to force air into me to get me to breathe. With a full face mask I pulled it off so I could
exhale and start breathing again. Is this common or rare and what causes it?
Machine is a BiPap Respironics autoSV with heated humidity.

[Goofproof]

What pressures are you using, you should be able to exhale over any pressure the machine uses. Jim

[den942]

What pressures are you using, you should be able to exhale over any pressure the machine uses. Jim

I don't really know what it is. I'm pretty illiterate on the machine. I may have been able to breath out if I
wasn't pretty much in a panic mode waking up. As I was waking it sure seemed that I couldn't breathe out
and the machine was puffing air into me rapidly..

[Goofproof]

You have a very costly machine, most people don't have those unless they are very rich, or have very bad problems, I'd know how mine was set up before I turned it on. It's important to learn all you can about your treatment, and take a active part in it. Getting the software and reader for it is a useful addition too. If I breath out hard and fast my mask seals fail and the air escapes at any pressure the machine can push. Jim

[Snoredog]

You are using a SV machine most likely because you also have central apnea or Complex Sleep Disordered Breathing (CSDB).

The machine you are using is supposed to address periodic breathing and central apnea as well as keep obstructive apnea at bay. It sounds like the back-up rate is not set up correctly. You need to dump the smart card with Encore software to see what is happening. The machine should not be doing what it is doing, if you stop breathing from a central it is supposed to revert to machine mode and kick start your breathing again.

It is in your best interest to get the User or Clinical manual and learn what it does and how you can adjust it yourself. Suggesting anything else without a report on that machine would only be guessing.

[freepostg]

You have a very costly machine, most people don't have those unless they are very rich, or have very bad problems, I'd know how mine was set up before I turned it on. It's important to learn all you can about your treatment, and take a active part in it. Getting the software and reader for it is a useful addition too. If I breath out hard and fast my mask seals fail and the air escapes at any pressure the machine can push. Jim

I'm not very rich...but I do have a pretty nice fish tank..that probably costs as much as the machine in question. -not that this has anything to do with the post..but I certainly enjoyed the " very rich" point!

[den942]

You have a very costly machine, most people don't have those unless they are very rich, or have very bad problems, I'd know how mine was set up before I turned it on. It's important to learn all you can about your treatment, and take a active part in it. Getting the software and reader for it is a useful addition too. If I breath out hard and fast my mask seals fail and the air escapes at any pressure the machine can push. Jim

Does being on Disability Social Security count as being rich? When I was sent home with it, I was told it was set for
what I needed and there was only two settings I could change, the heat temp on the humidifier and the ramp up.
The smart card knows what it needs to do.

[Goofproof]

It sounds like they are treating you in the mushroom mode, in the dark & well fertilired. Surely you have something serious going on, I doubt if they got by with setting you up with that machine if you don't need, most people end up with the cheapest leaf blower they can find. Get back to you doctor and get it ironed out as soon as you can, something is wrong here in the way it's setup. Jim

[tuna]

You have a very costly machine, most people don't have those unless they are very rich, or have very bad problems, I'd know how mine was set up before I turned it on. It's important to learn all you can about your treatment, and take a active part in it. Getting the software and reader for it is a useful addition too. If I breath out hard and fast my mask seals fail and the air escapes at any pressure the machine can push. Jim

I'm not very rich...but I do have a pretty nice fish tank..that probably costs as much as the machine in question. -not that this has anything to do with the post..but I certainly enjoyed the " very rich" point!

I know what you mean! I have spent over a $1000.00 on a 55 gallon saltwater aquarium! But it is nice and the fish are happy!

[ozij]

Several times I have woke up unable to exhale because my lungs were full but the machine was
trying to force air into me to get me to breathe. With a full face mask I pulled it off so I could
exhale and start breathing again. Is this common or rare and what causes it?
Machine is a BiPap Respironics autoSV with heated humidity.

Your machine is not very common because it is so specialized. I doubt though that your reaction is one that is expected on that machine. I'd contact the doctor whe set you up with it.

I've read - much too frequently for comfort - of cases where the machine provider did not know enough about a machine, and handed it to the patient with the wrong set up. I would therefore ask the doctor or sleep clinic to check the machine's setup just be sure.

O.

[-SWS]

Several times I have woke up unable to exhale because my lungs were full but the machine was
trying to force air into me to get me to breathe. With a full face mask I pulled it off so I could
exhale and start breathing again. Is this common or rare and what causes it?
Machine is a BiPap Respironics autoSV with heated humidity.

This somewhat common problem is called "breath stacking". Decreasing "timed inspiration" on the machine can sometimes help, but not always.

The crux of the problem is that you're not fully exhaling before entering the machine's IPAP phase for that next breath in. When exhaled volume falls short of inhaled volume, you gradually or sometimes even quickly accumulate that surplus of inspired air. This is inspired surplus air that needs to be purged via exhalation, but just doesn't quite become fully purged or expired. It becomes a trapped pocket of air instead. Presumably that surplus or pocketed air just doesn't quite get purged thanks to stretch related chemoreceptor input being either incorrectly translated or over-ridden via defensive reflexology----a somewhat common unintentional side effect of BiLevel therapy (defensive reflexive skew is my theory only---and most definitely not established medical fact).

Be sure to tell your clinician(s) about your tendency to "breath stack" while using the BiPAP AutoSV at its current settings.

[den942]

Several times I have woke up unable to exhale because my lungs were full but the machine was
trying to force air into me to get me to breathe. With a full face mask I pulled it off so I could
exhale and start breathing again. Is this common or rare and what causes it?
Machine is a BiPap Respironics autoSV with heated humidity.

This somewhat common problem is called "breath stacking". Decreasing "timed inspiration" on the machine can sometimes help, but not always.

The crux of the problem is that you're not fully exhaling before entering the machine's IPAP phase for that next breath in. When exhaled volume falls short of inhaled volume, you gradually or sometimes even quickly accumulate that surplus of inspired air. This is inspired surplus air that needs to be purged via exhalation, but just doesn't quite become fully purged or expired. It becomes a trapped pocket of air instead. Presumably that surplus or pocketed air just doesn't quite get purged thanks to stretch related chemoreceptor input being either incorrectly translated or over-ridden via defensive reflexology----a somewhat common unintentional side effect of BiLevel therapy (defensive reflexive skew is my theory only---and most definitely not established medical fact).

Be sure to tell your clinician(s) about your tendency to "breath stack" while using the BiPAP AutoSV at its current settings.

What you described is what I think is happening. I have noticed a couple times that exhaling slowly will cause the
machine to give a puff of air to stimulate breathing before I completely exhale. If there is no response, it will give
bigger puffs of air more rapidly to get a response of an inhale. I think these are the current settings as they are
written on my receipt for the machine:
Max IPAP +19
Min IPAP +12
EPAP + 9
Rate= 10
IT 1.2
RT 3

Thanks a lot for the reply. It sure sounds like Breath Stacking could be the problem. It only happened a few times
in a year so it isn't a big problem. Knowing what it is sure helps.
When I had my sleep study done it was on a Tuesday. They had me come back on Friday so I knew there was a
problem. On my return I was told my O2 level was dropping to 38% at times and I kept them from getting bored
during my test. The machine has for the most part worked flawlessly. I was surprised because it is a complicated
machine. Having been a machine designer I can appreciate things that work very well.

Thanks again. This board sure has been informative for me.

[Wulfman]

If you want/need a copy of the manual and setup info, PM me with your e-mail address.

Den

From the manual:

3.2.2 Back-up Breath Rate Controls
In addition to the pressure controls, the device may be configured to deliver machine-triggered breaths
if the patient does not spontaneously breathe at a determined rate. Back-up breaths are machine-triggered,
machine-cycled breaths. The Rate and Time Insp controls are used to configure back-up breaths
to one of three selections.

Control / Settings Description

Back-up Rate: OFF
No back-up breaths are delivered to the patient. The initiation of each breath is exclusively controlled by the patient. The device triggers to IPAP in response to spontaneous inspiratory effort, and cycles to EPAP during exhalation. Figure 3-4 illustrates the trigger and cycle concepts.


Back-up Rate: 4-30
Time Insp: .5 - 3
This selection ensures that the patient will receive a minimum number of breaths per minute if their spontaneous breathing rate drops below the breath rate specified by the Rate control. If the patient fails to initiate an inspiration within the breath period determined by the control, the device triggers a timed breath. The duration of each breath is controlled by the
Time Insp control. Figure 3-5 illustrates patient-triggered and machine-triggered breaths when the back-up rate is 4-30.


Back-up Rate: Auto
With Auto selected, the back-up rate and the time of inspiration are automatically determined by the device. Spontaneous breaths are used to compute an average breath period and inspiratory period. In CSR, the 2 to 3 breaths prior to the central apnea are insufficient to ventilate. Thus, tidal volumes less than 100 ml are not counted as a breath. Timed breaths
are delivered in groups of 5 breaths. The First Timed breath has separate timing criteria as compared to the subsequent 4 breaths. Figure 3-6 illustrates breathing intervals when the back-up rate is Auto.

[-SWS]

I think these are the current settings as they are written on my receipt for the machine:

IMO it's a good idea to learn how to at least check the actual settings in your machine against those prescribed values. Not to sound overly harsh, but as ozij correctly points out, we have seen very many machines set up incorrectly by clueless DME providers. Then again we also have some DME providers who post here that are nothing short of superb IMO. I'd personally take Wulfman up on his typically generous offer for the clinician manual if I were in your shoes.

Max IPAP +19
Min IPAP +12
EPAP + 9

These values are undoubtedly common and reasonable for many. Nothing out of the ordinary here IMO.

Rate= 10
IT 1.2

You'll see in the BiPAP AutoSV clinician manual that Backup Rate (yours is prescribed at 10) and Inspiratory Time (yours is prescribed at 1.2) generally work together to achieve not only breath rate, but also a ratio of inspiration to expiration (I/E). Respironics does not want time spent in inspiration to exceed time spent in expiration. Accordingly, as a clinician enters a value for Backup Rate, Inspiratory Time may automatically adjust downward in the process so that time spent in I does not exceed time in E. That automatic adjustment of IT during clinician setup will occur so that IT is set at exactly half the value determined by Backup rate.

So with that Backup Rate of 10 breaths per minute, Respironics will assume a time of 6 seconds per breath. If Respironics needed to automatically adjust Inspiratory Time in your case (and Respironics clearly does not), then that 50/50 ratio rule would make sure that IT is set at half of your 6 seconds. If IT were above 3 (and it is not) then the Respironics setup algorithm would set that IT value at exactly 3 to automatically achieve a 50/50 I/E ratio.

So your two values above kind of hint at your sleep lab quite possibly having wrestled a bit with your breath stacking problem. That Rate of 10 allows for each breath (I+E) to be as slow as 6 seconds. And that IT allows for each inspiratory phase (each breath in) to be no longer than 1.2 seconds in duration. Those settings clearly favor allowing you to spend significantly more time in the expiratory phase (breathing out) to cope with that breath stacking tendency. I doubt you can or should set that IT much lower. Ratio-wise IT is already set pretty low.


Those 10 and 1.2 settings kind of hint at your breath stacking problem in the lab IMO.

RT 3

That's a rise time of 0.3 seconds, by the way. Very reasonable IMO. But RT=3 also happens to be the default or "hard coded" value (the latter actually) when BiFlex is turned on. Algorithmically BiFlex tries to account for the dynamics of elastic recoil and other dynamic changes in respiratory resistance. Great feature for most people. However, algorithms are not infallible IMO. Some people are known to experience breath stacking simply by having the Flex feature turned on. If BiFlex is enabled, you might want to try experimentally turning it off to see if that helps with the breath stacking.

Lastly, beware that message boards can be a "dial wingers" paradise. In general people love to help. And in general some helpful people simply don't know what it is they don't know---strange as that entirely lacking type of self assessment sounds. Proceed with caution if the dial wingers decide to woo you.

[Wulfman]

Lastly, beware that message boards can be a "dial wingers" paradise. In general people love to help. And in general some helpful people simply don't know what it is they don't know---strange as that entirely lacking type of self assessment sounds. Proceed with caution if the dial wingers decide to woo you.

Whatchu talkin' 'bout Willis?

When I read the part I bolded, I thought of this......

"Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know." - Donald Rumsfeld

Yes, proceed with caution.....don't be a "dial winger" unless/until "you KNOW what is is you don't know"....

Den