AHI changes with altitude

[cappy]

Hi all, it has been a long time since I posted here. I have been on CPAP for over 4 years now. A month ago, I went from the S9 to the AirSense 10 Autoset with FX Quattro full face mask on both machines. Pressure is set at 12-14. I travel between sea level and 5,300 feet regularly. At sea level, my AHI is 5 or less. At 5,300 feet, my AHI is 16-18 events per hour. I was told that the AirSense 10 adjusts automatically for altitude but I am not seeing that in the results. My pressure is in the 95th percentile at 13.9 and I am in the process of getting the higher end adjusted to 16, but that hasn't happened yet. Any thoughts here? Does anyone travel to higher altitudes and have a similar experience?

[LSAT]

Hi all, it has been a long time since I posted here. I have been on CPAP for over 4 years now. A month ago, I went from the S9 to the AirSense 10 Autoset with FX Quattro full face mask on both machines. Pressure is set at 12-14. I travel between sea level and 5,300 feet regularly. At sea level, my AHI is 5 or less. At 5,300 feet, my AHI is 16-18 events per hour. I was told that the AirSense 10 adjusts automatically for altitude but I am not seeing that in the results. My pressure is in the 95th percentile at 13.9 and I am in the process of getting the higher end adjusted to 16, but that hasn't happened yet. Any thoughts here? Does anyone travel to higher altitudes and have a similar experience?

Why don't you just do it...what are you waiting for?

[Pugsy]

What is the breakdown into each category (Central/CA, OA, Hyponea) when you are at altitude and the AHI is too high?

I have been to over 10, 000 feet with my machine (not the same as your brand but it will auto adjust for altitude up to 8,000) and the AHI was pretty much the same.
They do auto adjust up to a point and you were below that point.

I have an idea about why the higher AHI but I need to know the event category breakdown to see if that idea is viable.

Otherwise we need to see a software report daily details to see what the pressure is doing along with the other usual stuff.

[Wulfman...]

Hi all, it has been a long time since I posted here. I have been on CPAP for over 4 years now. A month ago, I went from the S9 to the AirSense 10 Autoset with FX Quattro full face mask on both machines. Pressure is set at 12-14. I travel between sea level and 5,300 feet regularly. At sea level, my AHI is 5 or less. At 5,300 feet, my AHI is 16-18 events per hour. I was told that the AirSense 10 adjusts automatically for altitude but I am not seeing that in the results. My pressure is in the 95th percentile at 13.9 and I am in the process of getting the higher end adjusted to 16, but that hasn't happened yet. Any thoughts here? Does anyone travel to higher altitudes and have a similar experience?

It automatically adjusts for altitude, but that doesn't mean your pressure settings are "optimal".
I couldn't function with AHI numbers like that.
I live at over 5800 ft. elevation, year round, and my AHI numbers are around 0.2 - 0.3.

You need to jack up your pressures till you get your numbers down.
At a higher altitude you're breathing air with less oxygen in it.

Are you monitoring your therapy with SOFTWARE? ( Or just getting numbers from the LCD screen? )

As Pugsy said, you need to look at the breakdown of the type of events you're having, too.


Den

.

[Pugsy]

You need to jack up your pressures till you get your numbers down.

Nope. More pressure won't fix cappy's high AHI.
The bulk of his AHI change from lower altitude to higher altitude is Central and more pressure isn't going to fix it and might make things worse.

I heard from cappy privately.
He travels for work to higher altitude and sometimes stays there for a week or two or three. His AHI is only higher (because of the centrals) for about the first 4 days that he is at the higher altitude and then it returns to his normal AHI like what he has at home.
This has been going on like this for years.
It takes the 4 days for his body to get acclimated to the less oxygen in the air and during that time the unstable breathing which manifests itself as centrals (probably has complex sleep apnea during this time frame) will happen. Once his body has adjusted the AHI drops down and the centrals go away until the next time he returns after some time at home and the body has to readjust all over again.

He does report that he has always wondered by he feels like crap the first 4 days...now he knows.
Is it something bad enough to do anything about...don't know but that is something he can chat with his doctor about. A possible solution would be to keep an ASV machine at the higher altitude address for use there.

Edited to include Wulfman's post in its entirety since it upset him that I elected to respond to one specific area.

It automatically adjusts for altitude, but that doesn't mean your pressure settings are "optimal".
I couldn't function with AHI numbers like that.
I live at over 5800 ft. elevation, year round, and my AHI numbers are around 0.2 - 0.3.

You need to jack up your pressures till you get your numbers down.
At a higher altitude you're breathing air with less oxygen in it.

Are you monitoring your therapy with SOFTWARE? ( Or just getting numbers from the LCD screen? )

As Pugsy said, you need to look at the breakdown of the type of events you're having, too.

[palerider]

You need to jack up your pressures till you get your numbers down.
At a higher altitude you're breathing air with less oxygen in it.

it's *completely* irresponsible to spew out advice like this without even bothering to get any information first, like "what is that AHI comprised of?"

[Wulfman...]

Well, when you two edit out my other comments or hide pertinent information, you can make it look like I said something "irresponsible"!!!

Are you monitoring your therapy with SOFTWARE? ( Or just getting numbers from the LCD screen? )

As Pugsy said, you need to look at the breakdown of the type of events you're having, too.
And, when other information is not posted, it also compounds the problem of responding to the posts.

You need to jack up your pressures till you get your numbers down.

Nope. More pressure won't fix cappy's high AHI.
The bulk of his AHI change from lower altitude to higher altitude is Central and more pressure isn't going to fix it and might make things worse.

I heard from cappy privately.
He travels for work to higher altitude and sometimes stays there for a week or two or three. His AHI is only higher (because of the centrals) for about the first 4 days that he is at the higher altitude and then it returns to his normal AHI like what he has at home.
This has been going on like this for years.
It takes the 4 days for his body to get acclimated to the less oxygen in the air and during that time the unstable breathing which manifests itself as centrals (probably has complex sleep apnea during this time frame) will happen. Once his body has adjusted the AHI drops down and the centrals go away until the next time he returns after some time at home and the body has to readjust all over again.

He does report that he has always wondered by he feels like crap the first 4 days...now he knows.
Is it something bad enough to do anything about...don't know but that is something he can chat with his doctor about. A possible solution would be to keep an ASV machine at the higher altitude address for use there.

Well, I searched through his past posts and found nothing regarding Centrals. I did find that in 2012 he was using Sleepyhead that apparently had a known problem.

And, I don't believe you can say for sure that a little higher pressure would have an adverse effect on the Centrals......until it's been tried.

Back here, he was using a fixed pressure of 11 cm. and getting AHIs less than 5.0.

viewtopic.php?f=1&t=81781&p=742992#p742992

Does he have a copy of his sleep study and were Centrals noted in it?


Den

.

[palerider]

Well, when you two edit out my other comments or hide pertinent information, you can make it look like I said something "irresponsible"!!!

you did say something irresponsible, your words are right there in your original post, but I suppose you can go and edit that to hide what you said.

telling people they need more pressure without even seeing a chart, or even finding out what their increased AHI is made up of? yeah, that is irresponsible, and potentially damaging 'advice'.

And, I don't believe you can say for sure that a little higher pressure would have an adverse effect on the Centrals......until it's been tried.

SERIOUSLY? you're suggesting that it's appropriate to treat centrals with more pressure??

[Pugsy]

Well, when you two edit out my other comments or hide pertinent information, you can make it look like I said something "irresponsible"!!!

Would it make you feel better if I go edit things so that all of your response was included?
I will go do that right now.

And, I don't believe you can say for sure that a little higher pressure would have an adverse effect on the Centrals......until it's been tried

I didn't say that it would for sure have an adverse affect...I said

more pressure isn't going to fix it and might make things worse.

did you miss the word "might"?

Finally..more pressure is never advised when a large number of centrals are present because we don't know what is causing them.
I can't believe you would even go there in your thinking.
More pressure won't fix centrals...Period...even if it doesn't make them worse it sure as hell isn't going to make them go away and it won't help oxygen saturations either. If the air way is open and no breathing is happening...doesn't matter how much oxygen is in the air that isn't going down the airway because more pressure can't ventilate like that.

Well, I searched through his past posts and found nothing regarding Centrals.

I didn't search past posts. He sent me a private message in response to my above questions about the AHI breakdown.

I heard from cappy privately.

I don't normally share the contents of PMs unless I am told that it is okay. I wouldn't have said anything at all here in this thread past what I first said if you hadn't told him to go "jack up the pressures" because I had already explained my thoughts privately in PM and I didn't see the need to do it here until someone tells him to "jack up the pressures" without even knowing what is going on.

[palerider]

And, I don't believe you can say for sure that a little higher pressure would have an adverse effect on the Centrals......until it's been tried

Finally..more pressure is never advised when a large number of centrals are present because we don't know what is causing them.
I can't believe you would even go there in your "thinking"..

(fixed that for you )

[Wulfman...]

I didn't say that it would for sure have an adverse affect...I said

more pressure isn't going to fix it and might make things worse.

did you miss the word "might"?

Finally..more pressure is never advised when a large number of centrals are present because we don't know what is causing them.
I can't believe you would even go there in your thinking.
More pressure won't fix centrals...Period...even if it doesn't make them worse it sure as hell isn't going to make them go away and it won't help oxygen saturations either. If the air way is open and no breathing is happening...doesn't matter how much oxygen is in the air that isn't going down the airway because more pressure can't ventilate like that.

Well, I searched through his past posts and found nothing regarding Centrals.

I didn't search past posts. He sent me a private message in response to my above questions about the AHI breakdown.

I heard from cappy privately.

I don't normally share the contents of PMs unless I am told that it is okay. I wouldn't have said anything at all here in this thread past what I first said if you hadn't told him to go "jack up the pressures" because I had already explained my thoughts privately in PM and I didn't see the need to do it here until someone tells him to "jack up the pressures" without even knowing what is going on.

Well, actually you said.......

Nope. More pressure won't fix cappy's high AHI.

More pressure won't fix centrals...Period...even if it doesn't make them worse it sure as hell isn't going to make them go away and it won't help oxygen saturations either.

Maybe not, but he initially indicated he was contemplating working his pressure up to 16 cm.

Are they "true" Centrals or are they just "Open Airway" events or your favorite......"SWJ" ? ( Sleep/Wake/Junk )
At what pressure do they occur? Higher or lower?
When you go from low altitude to higher altitude, you're breathing less oxygen and can easily "crash" when falling asleep.
I can imagine all kinds of scenarios with changing altitudes and CPAP pressures and events.
But, it's like our old arguments about fixed or pressure ranges......you don't know FOR SURE what will happen until you try it.

I also was under the impression that ASV machines, which were designed to treat Centrals, could put out LOTS or pressure.


Den

.

[palerider]

wulfman going the way of avi?

or just flaunting his ignorance of modern tech?

needs to read up on how ASVs work, and why his statement is nonsensical?

enquiring minds want to know.

[avi123]

As of Dec 2011:

"For patients living at altitude with central sleep apnea syndromes, adaptive servo-ventilation has led to significant improvements in AHI compared to noninvasive PAP.24 Treatment with respiratory assist devices (RADs) such as adaptive servo-ventilation, in patients with central apnea has been shown to lead to a dramatic improvement in achieving AHIs in the optimal treatment range (AHI < 5.0) during PAP titration.25,26 Clinically, utilization of these systems is limited by cost, adaptability to existing titration protocols, and a limitation in the number and quality of applicable research studies. This study indicates that the O2 > CPAP/Bilevel PAP protocol used in this study is effective in treating altitude-associated central apnea in OSA patients as an alternative to RAD systems. This approach has its own difficulties: (1) a level of technical expertise during PAP titration is required beyond that required in the use of RAD systems, and (2) a second night of titration is often required in a patient grouping that demonstrates, at least in this study, a high potential for failure to appear for the second study. It is possible that OSA patients developing central apnea on treatment will be more likely to tolerate RAD systems for treatment However, at present, no comparative studies utilizing alternative treatment modalities for central apnea are available."

Source:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3227706/

[Wulfman...]

wulfman going the way of avi?

or just flaunting his ignorance of modern tech?

needs to read up on how ASVs work, and why his statement is nonsensical?

enquiring minds want to know.

Oh, but I have. And I also have lots and lots of saved documents about them. They've been around for quite a few years.

Let's see.........

viewtopic/t81340/What-on-earth--is-ASV.html

by Pugsy on Fri Aug 24, 2012 12:55 pm

ASV Adaptive servo ventilation machine.
Several different modalities...used for special cases where people have a lot of central apnea or all central apneas or a combination of obstructive and central events.
It acts like a ventilator and will actually force a breath if you don't breath on your own. Usually with a big burst of pressure.
Considered non invasive therapy.. Invasive with be the type of ventilators you see in the movies with the machine doing all the breathing through a trach in the throat and hooked up all the time.
ASV machine don't breathe for you unless it thinks you aren't doing good enough job on your own.

https://www.resmed.com/assets/documents ... ow_eng.pdf

http://www.alaskasleep.com/blog/adaptiv ... leep-apnea

Now, these could be some "serious" pressures........25 - 30 cm.

IPAP Min - 4 to 30 cm H2O
IPAP Max - 4 to 30 cm H2O
EPAP - 4 to 25 cm H2O
Breath Rate - 4 to 30 BPM
Greater of ± 1 BPM or ± 10% of the setting (when measured over a 4 minute period)
Timed Inspiration 0.5 to 3.0 seconds ± (0.1 + 10% of the setting) seconds
Ramp Duration 0 to 45 minutes ± 10% of the setting
Rise Time 1 to 6 ** ± 25%***


Den

.

[Pugsy]

Maybe not, but he initially indicated he was contemplating working his pressure up to 16 cm.

I think that idea was because of the 4 to 5 ish AHI he was having at home and the AHI wasn't primarily central.
I didn't even go there in my thoughts to him. He was going to send me a detailed software report but I haven't got it yet and really didn't need it for the central discussion.

Are they "true" Centrals or are they just "Open Airway" events or your favorite......"SWJ" ? ( Sleep/Wake/Junk )
At what pressure do they occur? Higher or lower?
When you go from low altitude to higher altitude, you're breathing less oxygen and can easily "crash" when falling asleep.
I can imagine all kinds of scenarios with changing altitudes and CPAP pressures and events.
But, it's like our old arguments about fixed or pressure ranges......you don't know FOR SURE what will happen until you try it.

I treat all machine reported Centrals/Clear Airway Events as "real" until proven otherwise. So I never suggest more pressure until we have a better idea what the "centrals" are...real or not.

I did some extensive reading quite a while ago when I was trying to help someone else living at high altitudes who was having centrals. It's carbon dioxide levels that trigger the brain to wake up and send the "breathe" message...It's not the oxygen content in the blood. From what I gather at altitudes the breathing can become unstable and the person blows off/exhales too much carbon dioxide and it doesn't get a chance to build up to the levels to where the brain wakes up and thinks "Oh..Carbon dioxide levels getting up there so I guess the dude needs to breathe..and it sends the breathe signal".
Why this happens to some and not others I don't know. I suppose it is like when some people get put on cpap that never had centrals and they drew the short straw and they end up one of the 10 to 15 % of the people who get Complex Sleep Apnea simply due to the cpap therapy for their Obstructive Sleep Apnea.

I do know that this is fairly common with people at altitude who aren't used to the higher altitude.
Once the body gets acclimated the centrals normally will fade away as the unstable breathing ceases.
The fact that the OP says his AHI returns to what is his normal at home...after 4 days and has seen this happen repeatedly over multiple years..sure points to the centrals as being the real deal and they go away on their own when he is at altitude long enough for the body to adjust.

So in this situation...I don't see the need to go the SWJ or post arousal discussion...there's a reasonable explanation as to their cause and they go away after a relatively short time. Now if they didn't go away then we dig deeper.

I also was under the impression that ASV machines, which were designed to treat Centrals, could put out LOTS or pressure.

It's not really LOTS of pressure...they only go up to 25 cm (they used to go up to 30) which isn't all that much in the grand scheme of things. What they do is give that pressure in a short big burst and it isn't sustained and it happens quickly instead of the slow upward movement normally associate with auto adjusting pressures.
We are talking it might go to 22 or 25 within 10 to 15 seconds...fairly rapid when compared to what regular machines do. It's that "burst" that seems to sort of jump start the body so that it gets out of the unstable breathing mode and starts in with its normal breathing mode. And it doesn't stay up there very long...we are talking really short term "burst". Nothing anywhere near the length of time for the pressure to go up or down like we see with apaps. How that burst changes the Carbon dioxide levels so that the breathing goes back to normal...I don't know the mechanics behind that.

More continuous single xpap pressure isn't going to fix or prevent centrals that are the result of unstable breathing. It doesn't help get the carbon dioxide levels up so that the brain knows that it needs to signal the body to breathe and it could potentially make things worse because it can cause too much carbon dioxide "wash out" which could make the unstable breathing worse. If the carbon dioxide levels don't get up for whatever reason...the brain isn't going to send the signal to breathe.
I don't know that more continuous single pressure will even help with desats because if the person isn't breathing they aren't getting any fresh air in the lungs anyway. Kinda like if a person was on O2...doesn't matter if the air isn't going into the lungs for some reason or other.

Now if the centrals are post arousal and we see them on the reports in conjunction with a large number of OAs or hyponeas along with other signs of OSA not being optimally treated...then yeah try to fix the OSA related stuff with more pressure and cross your fingers the Central stuff goes away with the better therapy for the OSA stuff but I always warn those people to keep one eye real close on the centrals when we are doing that. I try to always explain all of that ahead of time so that they know why the more pressure is suggested and what the pros and cons are to that increase.

If you had said "let's see what the AHI is made up of...you might need more pressure" I wouldn't have said anything about what you said.
Again...until I know what I am fighting I don't want to go telling people to increase the pressure.
I don't believe in going down that road. It could maybe hurt someone one and I won't go there.
Maybe I am being over cautious but if I am going to err..it's going to be on the side of caution whenever possible.