Machine trying to change breath rhythm?

I did my sleep test. They woke me at about 4:15AM to put on the cpap machine. As I sat with it on my face even before I started back to sleep it felt like it was trying to change the rhythm of my breathing. I would be breathing out and the machine would suddenly feel like it decided it was time for me to breathe in. Almost as if someone was doing mouth to mouth respiration on me. It would even happen when talking to the tech with the mask on.

Is this normal? Just something that will stop when I get my lungs trained? Is it supposed to feel like a battle with the mask on or is this just me? I had thought that these machines just applied a constant pressure.

Because it was a study they did not tell me much of anything. They just told me that the results will be back in a week or two. He did say when finished that “we are done torturing you, let me get you unhooked." I do not know what model of cpap they used or the settings.

Welcome! A CPAP will not try to change your breathing rhythm, but it's normal to feel a tad out of control when first using one. If the pap senses you are not breathing or that your airway isn't open, it will blow a quick puff of air to see if you will breathe (phillips respironics machines do three quick puffs, anyway). You may have been feeling that happen.

Many people, once they get a machine at home, will use them before going to bed (while watching television or out in the family listening to music) in order to get used to it so that it becomes easier to sleep with.

The CPAP's not a ventilator, so it can't determine when you can breathe. But if the machine is set with EPR/C-flex/A-flex, etc. on, during your expiration you'll arrive at a point where that feature switches off and you're again exposed to your full therapy pressure, so the feeling might be as you describe. You'll get used to it. The trick is not to fight the machine. The machine takes its cues from what you do. Try to relax and not breathe too deeply. Eventually you'll nod off and the machine will do its thing without your even knowing it. Since what you described happened in a sleep lab setting, maybe the techs didn't have the machine set up correctly or were a little ham-handed when you first were fitted with the mask.

What you ask is a very good question to put to your sleep doc.

jacobsbd wrote:I did my sleep test. They woke me at about 4:15AM to put on the cpap machine. As I sat with it on my face even before I started back to sleep it felt like it was trying to change the rhythm of my breathing. I would be breathing out and the machine would suddenly feel like it decided it was time for me to breathe in. Almost as if someone was doing mouth to mouth respiration on me. It would even happen when talking to the tech with the mask on.

Is this normal? Just something that will stop when I get my lungs trained? Is it supposed to feel like a battle with the mask on or is this just me? I had thought that these machines just applied a constant pressure.

Because it was a study they did not tell me much of anything. They just told me that the results will be back in a week or two. He did say when finished that “we are done torturing you, let me get you unhooked." I do not know what model of cpap they used or the settings.

It sounds like they were doing a bi-level titration on you. The timing in the pressure change from exhale (EPAP) to inhale (IPAP) is called "Rise Time" and can be adjusted within the machine's settings. Depending on the person doing your titration, it could be that they were trying to find your setting or they were not very skilled at determining the settings.


Den

It feels a bit like this to me when I am going to sleep, like the machine is anticipating my next breath, which it is. If you look at the curves for C-Flex or A-Flex in the provider's guide on my PR System One it shows pressure increasing before you take your next breath so it feels like it is forcing you to take a breath sooner than you want. If this rhythm is not to your liking, you may be more satisfied with therapy with no exhale pressure relief (C-Flex, C-Flex+, A-Flex for Respironics machines).

When I wake up in the morning I can no longer feel the pressure or the rhythm, like the machine is turned off, until I pull off the mask and get a blast of air.

Thanks.

He woke me up, hooked up a nose pillow mask and told me i had a choice of another mask if I had problems. He adjusted the staps and hooked an electrode back up that had come unhoocked, had me layback down and hit the lights on his way out.

I asked the tech about how if felt like it was forcing a breath, or out of adjustment and he said, "no it can't do that." very much a don't be silly attitude.

I ask for a mask change, He swapped in the nose mask. that was the only change he made before morning. Not sure how they are going to figure out the pressure I need but I will see.

jacobsbd wrote:I did my sleep test. They woke me at about 4:15AM to put on the cpap machine. As I sat with it on my face even before I started back to sleep it felt like it was trying to change the rhythm of my breathing. I would be breathing out and the machine would suddenly feel like it decided it was time for me to breathe in.

Hi Jacob, and welcome to the forum.
Yes this can happen - and not necessarily on bi-level (i.e. BIPAP) machines.
Modern machines have an "exhale relief" option - and in order for that to be applies in a helpful way, the machines have to keep correct track of you breathing. In Respironics machines, this called xFLEX, with x standing for A(uto) B(ipap) or C(onstant) - Flex drops the pressure when you exhale, bringing it back in slightly before you finish exhaling. This works great for many people - keeps their airway from collapsing as the exhale ends - but if the machines tracking is wrong -- as it is for some -- this can be a big problem.

I suggest you make sure to enquire which machine they were using, and do your best to rent a machine - of any type - for trial before you buy.

PAP therapy takes getting used to -- but if the machine misreads your breathing, you need to either turn off the exhalre relief, or use a machine made by another company. They are all software guided -- and the companies' approaches are very different.

O.

I do not know what sort of machine they had me on at the end. I do know they did not enter the room to adjust it after the mask swap.

Can the machines in the sleep study rooms be ramped up and down and otherwise adjusted remotely? If not I do not see how he could know what the proper pressures to set are.

Thanks

jacobsbd wrote:Can the machines in the sleep study rooms be ramped up and down and otherwise adjusted remotely? If not I do not see how he could know what the proper pressures to set are.

Yes. They can adjust the pressure remotely. It's normal in a titration to start the pressure low and then gradually increase it until all the apneas are eliminated. They can see the number of apneas you are having on a computer screen as they happen.

I agree with everyone else. What felt like the machine trying to control your breathing was almost certainly the expiration pressure relief (EPR also known as CFLEX or AFLEX). This is supposed to make it easier for you to exhale by sensing when you start to exhale and dropping the pressure slightly. Unfortunately it drops it only for a very short time and then goes back up. It doesn't sense when you are done exhaling so the pressure may go back up while you are still trying to breathe out. It drove me crazy and I found I could exhale without it so I turned it off. On my machine it's a standard user control - no need to get into special clinician menus to turn it on or off - using it is up to you. It's also true that as you get used to the pressure it may not bother you as much. Putting the mask on for the first time is always when the pressure feels worst.

I think it would be highly unusual for a sleep lab to use exhale relief when doing titrations.
And, not all exhale relief systems are created equal.


Den

Wulfman... wrote:I think it would be highly unusual for a sleep lab to use exhale relief when doing titrations.
And, not all exhale relief systems are created equal.


Den

I agree that would be unusual for a sleep lab to use. But what the poster described sure does sound like the way C-Flex works...bringing in the regular pressure before an exhalation is completely finished.

Many labs use Respironics machines, usually one designed for labs. The lab machines are capable of using bilevel mode, with or without a timed back up rate turned on. Bilevel machines (when "timed" is not turned on) are supposed to wait, and wait, and wait down at the EPAP (exhalation pressure)... and wait, and wait down there... indefinitely... UNTIL the person starts to breathe in again.

So, if the sleep tech was using plain bilevel mode during the titration, the tech was correct in saying -- "no it can't do that" when asked if the machine was "forcing a breath." Correct as far as he knew.

However.....

Respironics' "digital tracking" doesn't suit some people in identifying what's going on in with their exhalations. Several people I know have reported that exact same feeling of more pressure coming in before they are finished exhaling, when using a Respironics bilevel machine. Respironics' "Digital Tracking" doesn't "track" some people's breathing well.

Bi-Flex in Respironics bilevel machines is another thing that might cause a "forced" feeling for some people. Bi-Flex works like C-Flex at the beginning of an exhalation. In a bilevel machine, Bi-Flex drops the EPAP pressure just a little bit more...making the start of the already lower EPAP pressure be even a little bit lower the instant the person starts to breathe out. And, like C-Flex, Bi-Flex lets the regular pressure (in this case the low EPAP pressure) back in before the exhalation is finished.

So, if Bi-Flex was turned on during a bilevel titration, a feeing of a little bit more pressure coming back in while a person was exhaling could give a feeling of being forced to take another breath before ready -- to someone who might be very sensitive to the "feel" of what Bi-Flex does in a bilevel or what C-Flex does in a CPAP.

Whether or not Bi-Flex was turned on, Respironics' "digital tracking" doesn't track some peoples' inhale/exhale cycles well. Probably does for most, but not everyone:

viewtopic.php?p=555348#p555348
On page 3, -SWS wrote:
P.S. As a side note, I can't get Respironics' BiLevel (with or without Flex) to cycle comfortably for me. But the fact that EPR triggers very comfortably tells me to stick with Resmed BiLevel's if I ever need one... More importantly, I know better than to breathe into a tube and generalize either patient-response characteristics or even design characteristics based on my own potentially unique/anomalous breathing presentation. I'd recommend Respironics BiLevel, or the other brands, despite my own incompatible and unique breathing.


viewtopic.php?p=552899#p552899
-SWS wrote:
BTW, excessive, brief leak spikes can prematurely trigger IPAP---as they look like the start of positive/machine-outbound flow to a sensor. Also, expiratory pauses with a brief inhale "hitch" or false start---before true inspiration---can prematurely trigger IPAP.


viewtopic.php?p=553331#p553331
ozij wrote:
To give you an example:
My breathing pattern is such that it confuses the Respironics exhale inhale tracking - a Respironis BIPAP was the only machine I tried (after 4 years of therapy experience) which I could not even use through one night -- simply because that's the way I breathe. I belong to a small minority in this - but in bed at night I am 100% of the study, and the way the machine works for other people becomes irrelevant

The machines they use for in-lab titrations are pretty sophisticated and can perform all sorts of functions.
Just what they used for this poster is anybody's guess at this point.
My comments have been based on what I read in the initial post and what I suspect might happen in a (typical) sleep lab.

Den



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they called me this afternoon to set up a second sleep study to do titration so I guess I will know lots more when it is over.

I will make my first real call to insurance in the morning to get some idea of how they do machines.

Thanks for all the help