How bad can pressure induced central apnea be?

I know that too much pressure can cause central apneas. What I'm interested in is how long and severe can they be? Has anyone with this problem looked at their waveforms for pressured induced centrals and seen how long their duration is? Are they 100% non-breathing, or just reduced breathing?

Archangle, a central apnea is an open airway event. The brain does not tell the body to breathe, so I imagine no air is moving. As to duration, I don't know. From what I've read (take this with a grain of salt) the idea of pressure induced centrals is over emphasized.

Forum member Firehope definitely had pressure induced centrals. They say only 10 to 15 % of CPAP users get them. He is the only one recently that I know of with clear cut case of it. You might ask him to share his flow pattern.

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He is using EncoreViewer 2.0 which doesn't offer wave form but perhaps he would try SleepyHead for you so you could see wave form on the individual centrals.

archangle wrote: . . . how long and severe can they be? . . .

I believe it depends.

In some people, pressure centrals happen during titration but then go away completely after a while, once effective PAP stabilizes overall breathing.

In other people, effective PAP uncovers centrals that indicate formerly hidden health problems that need treatment.

Said another way:

CPAP-related CSA appears to represent a benign and transient phenomenon and is likely related to sleep fragmentation and sleep stage shifts that occur with initial CPAP titration. [But] the persistence of CSA despite adequate CPAP therapy may warrant further investigation for occult cardiovascular disease. -- http://chestjournal.chestpubs.org/content/132/1/81.full

archangle wrote: . . . Are they 100% non-breathing, or just reduced breathing?

When there is no signal to breathe, usually very little air moves, as I understand it. But reductions in breathing can be considered "central" too when they aren't the result of obstruction.

The thing to remember, though, is that harmless centrals are harmless, regardless of their length, within reason. Whereas centrals that are evidence of other health problems are mostly only useful to document in the context of uncovering those health problems. The important thing is what they mean, or don't mean, to a particular patient--not so much how long they last or what they look like, according to my way of looking at it, anyway.

But the whole idea that home PAP users diagnosed with simple OSA need to worry about pressure-induced centrals with changes in pressure is mostly just a myth/urban legend that DME RTs use to scare OSA patients, in my opinion. The existence of APAP machines proves that point.

I ain't no doc, though.

It may be a matter of symantics, but Merriam-Webster's dictionary of medical terms describes hypopnea as: Definition of HYPOPNEA: abnormally slow or especially shallow respiration. Whereas, the people at Mayo Clinic define Central Apnea as: Central sleep apnea is a disorder in which your breathing repeatedly stops and starts during sleep. Central sleep apnea occurs because your brain doesn't send proper signals to the muscles that control your breathing — Now for my opinion on the subject, and although I am NEW to the forum, I've been a hose-head for about eleven years. As you can see by the definitions, they are not the same, and I believe you are describing pressure induced hypopneas. I have strings of them on my charts and have had them for years. In the last month I've had one Non-Responding Incident (read as central apnea), and yes I woke up gasping for air, and one apnea. You can argue I have bad apnea treatment with almost all of my AHI coming from my HI. The hypopneas don't bother me since my body tells me to breathe when the CO2 rises. If it didn't I wouldn't be breathing at all. My best days, believe it or not seam to come with the highest hypopnea index that previous night. So I quit worrying about the HI,and work on keeping the leaks as low as possible, so my AI stays as low as possible. How many times have I read on this forum "my worst night on cpap is better than my best night without it."

I had cpap induced central apneas that did not go away with time. I don't know about how the waveform changed, but I do know that those apneas made my spo2 drop even though I was on cpap. Those hypoxic events made me feel bad the next day. I am now on S9 Adapt ASV, no longer have drop in spo2 and feel much better during the day. IMHO, I would not minimize the impact of ca's on the effectiveness of xpap therapy. My ahi runs at zero and I have been titrated to round out waveform.

Mary Z wrote:Archangle, a central apnea is an open airway event. The brain does not tell the body to breathe, so I imagine no air is moving. As to duration, I don't know. From what I've read (take this with a grain of salt) the idea of pressure induced centrals is over emphasized.

You're assuming that "central apnea" is an all or nothing event. That's not what waveform data from CPAP machines show. Many people have posted waveforms of "central apneas" scored by CPAP machines and there is a partial reduction in airflow, but there is definitely some breathing going on. Of particular interest to me is that the really low breathing may only be a short time period in the entire "duration" of the event, and the rest of the "event" is when the patient is actually doing a significant amount of breathing?

Someone posted the criteria used by some organization for scoring an event as a central apnea and it wasn't a "zero breathing" event, it was a "reduced by x% plus other criteria" event.

For instance, here's a 29 second "clear airway" event from my PRS1. Note that 29 seconds is half the width of the screen, so I was breathing somewhat for a considerable part of the "duration" of the event.

Bright Choice wrote:I had cpap induced central apneas that did not go away with time. I don't know about how the waveform changed, but I do know that those apneas made my spo2 drop even though I was on cpap. Those hypoxic events made me feel bad the next day. I am now on S9 Adapt ASV, no longer have drop in spo2 and feel much better during the day. IMHO, I would not minimize the impact of ca's on the effectiveness of xpap therapy. My ahi runs at zero and I have been titrated to round out waveform.

Sounds like you had a good diagnosis, mostly that they checked for O2 desats to be sure the central apneas were "real."

archanble, the problem is that untreated central apneas can lead to all the same issues as untreated obstructive apneas. It does not matter if the event is pressure induced or not.

I would stop breathing so long that after a minute my machine would turn off. I would awaken. I would go back to sleep. The machine would turn off. Etc. Turning off the 'auto off' feature did not really help.

By the time my current doctor prescribed ASV therapy, the resulting stress had led to permanent kidney damage as well as type 2 diabetes. I actually had a previous doctor say that central apnea was very rare so I could not have it ... Regardless of the number of my central apnea events! So the problem is that some sectors don't want to apply current technology to address their patients issues.

How bad can it be? In a word: Bad!

My titration study showed a dramatic increase in centrals at high pressure:

JohnBFisher wrote:archanble, the problem is that untreated central apneas can lead to all the same issues as untreated obstructive apneas. It does not matter if the event is pressure induced or not.

I would stop breathing so long that after a minute my machine would turn off. I would awaken. I would go back to sleep. The machine would turn off. Etc. Turning off the 'auto off' feature did not really help.

By the time my current doctor prescribed ASV therapy, the resulting stress had led to permanent kidney damage as well as type 2 diabetes. I actually had a previous doctor say that central apnea was very rare so I could not have it ... Regardless of the number of my central apnea events! So the problem is that some sectors don't want to apply current technology to address their patients issues.

How bad can it be? In a word: Bad!

"It does not matter if the event is pressure induced or not."

Well, since I'm asking about pressure induced centrals, it does matter in terms of this thread.

Do you believe your damaging centrals were pressure induced, or is it possible you had centrals before CPAP?

A sustained desat is not necessary for a central event to be "real," as I understand it.

Home machines can only estimate that an event MAY have been central. They cannot confirm apneas as being central in the way lab/center PSGs can by means of effort belts. PSGs have mostly standard criteria for labeling events. Home machines, on the other hand, use proprietary algorithms and proprietary definitions for patent reasons. Therefore, the estimated events from home machines should never be given the same weight as what is found during an attended PSG.

It is common for application of PAP to cause centrals during titration, but that does not necessarily mean they will continue or that the patient has central sleep apnea.

It is common for arousals to cause central events rather than for the central events to cause the arousals. That can be why "rounding the curve" helps reduce the centrals--the airway gets stabilized, so there are fewer arousals, which in turn, then, means that there are fewer stage shifts that would pause breathing. (When it is the state of the airway that is causing the arousals, anyway.)

The information we get from our home machines is very useful. But only as trending information. Not as diagnostic information. The info should be used to find the best pressure, but may not be all that useful for much else, all things considered.

Knowing whether an airway was open during an event, for example, can be useful information. But it is not the same thing as knowing that an event was truly central in nature. Sometimes obstruction is partial. Sometimes the airway closes during a central event. That is why we can't read too much into what our home machines tell us.

In my opinion.

The above is based solely on what I've read. I have no actual experience with any of it.

I don't have the data avaible to post, as the sleep studies were 2 years ago. However I had some experance with pressure induced Centrals during my two tiration tests. (*As a disclaimer let me note that I have central sleep Apnea, So your milage may vary)

When I was first tested without titration, I was seen to have about 45 Apnea Events a hour. My O2 levels would drop to the low 80's. During Titration on CPAP, and then on BiPAP, depending on the pressure being tested and used my Events at their highest broke 100 a hr. (Understandably they did not leave me at those preassures for a hour, but the rate of Central Apnea Events increased greatly) In addition my O2 stats dropped to under 70% during the titration. WHich really freaked the Tech out.

I had simmilar troubles on ASV machines. In the end I was put on a BiPap at 15/11 because that was where I scored the best out of all macines. I might just be a odd case, but for me pressure can and will induce Centrals. And they can be very very bad as was seen during my titration. One intresting thing to note, It was not a increasing number of events with High preassure, I saw a increase of events with lower preassures as well.

archangle wrote:... "It does not matter if the event is pressure induced or not."

Well, since I'm asking about pressure induced centrals, it does matter in terms of this thread.

Do you believe your damaging centrals were pressure induced, or is it possible you had centrals before CPAP?

No, no. I don't think you understand my statement. REGARDLESS of the underlying cause, if central apneas occur, they can and will damage your body. The underlying cause does NOT matter.

If you wonder if pressure induced apneas can reach 10 per minute or 20 per minute compared to other causes, then the answer once again is that it depends on the individual. You might have a very mild number of central apneas due to pressure. Or you might have a HUGE number.

But then the same is true for other causes of central apneas. If it is due to brain stem problems the number of apneas might be small or it might huge. Ditto if the central apneas are due to heart related problems. Ditto if due to opiate use. The number that might occur depends entirely on the individual. The score of the number of apneas might range from a minor blip on the sleep study to life threatening.

There is no set limit due to the cause of the central apnea. That is, we can not say:

If you have "x" then the central apneas will only be "mild". If you have "y" then they will be moderate. And if you have "z" then they will be severe.

There are people here who experience SIGNIFICANT jumps in central apneas as the pressure increased (as noted in a previous post).

Hope that makes more sense.

Some links to related discussions and to more wisdom and research from John, as compiled by Rested Gal:

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