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General Discussion on any topic relating to CPAP and/or Sleep Apnea.
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Aswab
 
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Pressure

Postby Aswab on Wed Feb 22, 2006 7:47 am

Hi Folks,

What are the symptoms and escalating side effects of too high a pressure? Is too high a pressure a serious problem? At what point? How does is manifest?

Thanks

David
O.G.S.D.K.

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WAFlowers
 
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Postby WAFlowers on Wed Feb 22, 2006 8:35 am

Some people have been known to exhibit central apneas at higher pressures. I am one of them.

"Higher" is a relative term, of course. What is a high pressure for me is low for many people.
The CPAPer formerly known as WAFlowers

snorzalot
 
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Postby snorzalot on Wed Feb 22, 2006 10:01 am

WA Flowers,

I also experience CSAs (Central Sleep Apneas) at higher pressures. During my original sleep study (this last round) they started with my old 1999 setting of 8 cm H2O which I knew didn't work as my wife reported snoring while using the CPAP equipment. Long story short, I was out of compliance for nearly seven years. In the middle of my study they turned the pressure up to 10 cm H2O which started causing CSAs very quickly. They didn't like the number of CSAs, so they stopped pressure adjustments at 10 cm H2O even though I was still having 22 apneas per hour. (50.5 untreated).

I started reading about CSAs the day after the study and to be honest the concept really scared me. A polysomnography therapist explained to me that CSAs are fairly common in patients that require higher cm H2O settings and that I needed to get used to the 10 cm H2O pressure for a bit and then do another titration study to start adjusting higher. My doctor claimed that I would need around 16 cm H2O (good guess) and that most likely I wouldn't tolerate that well without BiPAP which he ordered. During my titration study, my chart showed 0 CSAs! I was a bit amazed by the results since I had so many the first round, but a respiratory therapist and another polysomnography therapist told me they shouldn't have been counting them during the first study anyway which led me to believe they just didn't report them in the second polysomnogram I picked up from the sleep lab.

I ended up going to 18 cm H2O during my tritation study, but they found around 93% sleep efficiency at 16 cm H2O so that's where my current settings reside. I have the BiPAP Auto w/Bi-Flex, but it's running in straight Bi-PAP mode (3 Bi-Flex).

Obviously, I'm VERY interested in purchasing the card reader now so I can see for myself more precisely what is happening each night. I'm thrilled to report I slept a full 8 hours last night with only 1 noted wake up which is so rare. I woke up at midnight, turned on my side and my wife woke me up in that same position this morning :-) I'm still leary of the CSAs though based on my early readings so any comments about CSAs would be welcome!

Thanks!


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WAFlowers
 
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Postby WAFlowers on Wed Feb 22, 2006 11:02 am

snorzalot wrote:I'm thrilled to report I slept a full 8 hours last night with only 1 noted wake up which is so rare. I woke up at midnight, turned on my side and my wife woke me up in that same position this morning :-)

The good news is that you seem to be getting the treatment you need in order to get a good nights sleep. Congratulations!

The CPAPer formerly known as WAFlowers

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Postby Guest on Wed Feb 22, 2006 2:58 pm

How is a CSA event distinguished from an OSA event?

I need to be frank here in that I suspect my pressure is too low but I am not seeing the RT and Pulmonologist until late next month. I am currently at 8cm H2O and considering taking myself to 9 but perhaps that is not wise.

Since I have the Remstart Pro but not the Pro 2 the software will not help me a lot in figuring out this myself so I was wondering what risk I might run just adjuting it up a notch by myself.

I have put on a little weight since the sleep study (25 months ago) and sometimes when I lay on my back I get the same waking closure at 8cm that I get without the CPAP, but certainly not with the same frequency.

David


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Aswab
 
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Postby Aswab on Wed Feb 22, 2006 2:59 pm

Guest was me, David. I see how people get guested now.
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Postby GrumpyInKC on Wed Feb 22, 2006 4:11 pm

Aswab, I would call my doctor and see if he can get you a APAP that can record your events so he can have the data available for your next appointment.

Sounds ironic for me to recommend this since my doctor recommended it for me and I haven't decided if I am going to do it or not, but I don't believe my problems to be pressure related.


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WAFlowers
 
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Postby WAFlowers on Thu Feb 23, 2006 8:35 am

Anonymous wrote:How is a CSA event distinguished from an OSA event?

Simplified explanation (which is all I can give):
In CSA there is no obstruction but you aren't taking a breath anyway. With OSA you want to take a breath but can't becuase of an obstruction.

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Aswab
 
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Pressure OSA/CNSA

Postby Aswab on Thu Feb 23, 2006 10:09 am

I understand that but how is it distinguished as being CNSA v. OSA during evaluation/titration. Particularly when both events can be occurring for both reasons.

What is the indicator?

Thanks

David
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WillSucceed
 
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Postby WillSucceed on Thu Feb 23, 2006 10:57 am

OK, so, first and foremost, I'm not a Dr.
I'm just telling you the bit that I know. For a central apnea to occur, your brain stem does not send the signal required for you to breathe. This is, of course, very different from an obstructive apnea during which your throat is physically closed such that the air can't get through.

My Dr. explained pressure-induced central apnea like this: if you are in the car, travelling fast, and stick your head out the window, the force of the air hitting you in the face is enough to cause some O2 overload such that your brain does not send the signal for you to breath as regularly as it would if your head was NOT hanging out the window. The high CPAP pressure is no different than this. Centrals will happen and, he said, are not that big a deal because we will, eventually, take a breath when needed. Unfortunately, these centrals can cause micro-arousals which, are not good because they fracture your sleep. He told me that the patient can get used to the higher pressure and the number of centrals will reduce.

Some folk do have central apneas that occur because there is something going on in their brain stem such that the signal to breath does not get initiated. These folk are treated with a bi-pap that has a back-up rate; the machine tracks the number of breaths and initiates a breath if the patient does not breath appropriately. If you did not have centrals showing up at lower pressure, then, in all liklihood, this scenario does not apply to you.

I had a ton of centrals showing up during my first titration study when they had me at a pressure of 15. These reduced significantly over time and, when I lost some weight and was able to be at a lower pressure, they dropped down to only a few during the night. You should bear in mind that anybody (this includes non-OSA folk) can have central apneas during the night; this is considered normal.

If you are using an autopap, take a good look at the number of centrals that it thinks are happening. Hopefully, you will find them decreasing over time.

Buy a new hat, drink a good wine, treat yourself, and someone you love, to a new bauble, live while you are alive... you never know when the mid-town bus is going to have your name written across its front bumper!

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WillSucceed
 
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Postby WillSucceed on Thu Feb 23, 2006 11:01 am

What is the indicator?


If I have understood your question correctly, the indicator is that for a central, your airway is OPEN, but no air is moving; your diaphragm (sp?) has not received a signal to move and, as such, your lungs have not expanded (filled with air).

In an obstructive, the signal is sent and your diaphragm is moving, trying to inflate your lungs but the air can't get through the closed throat.

During the titration, the belts around your chest and stomach let them know that your diaphragm is moving, trying to inflate your lungs -this is how they know that it is NOT a central apnea. In the central apnea, your chest/stomach are NOT moving.

Buy a new hat, drink a good wine, treat yourself, and someone you love, to a new bauble, live while you are alive... you never know when the mid-town bus is going to have your name written across its front bumper!

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Postby NightHawkeye on Thu Feb 23, 2006 11:45 am

WillSucceed wrote:He told me that the patient can get used to the higher pressure and the number of centrals will reduce.

This seems to be a recurring theme . . .

I take it then that this involves a shift in CO2 threshold somehow. Perhaps the association is not so much pressure but rather that the person has developed an abnormal CO2 threshold caused by apnea which forces high concentrations of CO2 in the lungs. (I've read that buddhist monks and apnea divers can change their CO2 thresholds with a little practice.)

This would certainly alleviate a lot of the concern about centrals if they are largely a response to too much of a good thing during the early stages of CPAP treatment. Hmm . . ., yet another reason that APAP should be the standard of treatment, and also a good reason to go slow by limiting the highest pressure for a short period of time while an individual acclimates to CPAP therapy.

Regards,
Bill


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Postby Guest on Thu Feb 23, 2006 11:55 am

Great! Thanks, that is precisely what I was looking for and, yes, I understand you are not an MD.

I guess I still wonder what the APAP uses as an indicator of a CNSA?

I do not have an APAP. I am going to ask the sleep center to see if they one that the can and will lend me so there will be some results to interpret before my next visit in late March. I started on this thread because I suspect (without any empirical data) my pressure is too low, that I am not getting the full benefit, and was considering stepping up a notch without that empircal information and was wondering what the risk was. I'll wait. I am heavy, have put on some weight since my last study (which was, IMO, a fiasco I am skeptical of to begin with).

My suspicion is due to a physical closure at the back of my throat that, pre-CPAP, I experienced while on my back then later my left side and then even later my right side. This closure went away on the CPAP but now shows up occasionally when on my back (( am not on my back often) so I was wondering if the pressure is too low.

Thanks again.

David


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Aswab
 
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Postby Aswab on Thu Feb 23, 2006 12:11 pm

That was me, I got guested. Thanks again.
O.G.S.D.K.

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NightHawkeye
 
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Postby NightHawkeye on Thu Feb 23, 2006 9:45 pm

Anonymous wrote:I guess I still wonder what the APAP uses as an indicator of a CNSA?

Basic answer is that an APAP has no way of distinguishing between central and obstructive. However, the Respironics algorithm does know, at least some of the time, when an event is not responding to pressure increases and longs that in the output data as a non-responsive event.

Regards,
Bill


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