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Re: Continuous Pressure for Central Apnea
Posted: Thu Apr 25, 2019 9:51 pm
by katestyles
ajack wrote: ↑Thu Apr 25, 2019 9:38 pm
yes it does reduce exhale pressure. This can cause more CA, so it is said by those that know. so it alters the inhale and exhale pressure. or another way, the inhale pressure stays the same and the exhale drops. either way there is a difference.
I watched the video. It explains that if the flex makes the pressure drop below the pressure needed to hold the airway open, it can increase
obstructive apneas, but I don't see it say it causes centrals.
Perhaps I have the wrong video
Re: Continuous Pressure for Central Apnea
Posted: Thu Apr 25, 2019 9:53 pm
by katestyles
katestyles wrote: ↑Thu Apr 25, 2019 9:51 pm
ajack wrote: ↑Thu Apr 25, 2019 9:38 pm
yes it does reduce exhale pressure. This can cause more CA, so it is said by those that know. so it alters the inhale and exhale pressure. or another way, the inhale pressure stays the same and the exhale drops. either way there is a difference.
I watched the video. It explains that if the flex makes the pressure drop below the pressure needed to hold the airway open, it can increase
obstructive apneas, but I don't see it say it causes centrals.
Perhaps I have the wrong video
Ajack, please stop editing your posts so much - it is getting really confusing that they keep changing
Re: Continuous Pressure for Central Apnea
Posted: Thu Apr 25, 2019 9:56 pm
by Pugsy
Kate....
When we use the exhale relief feature it creates a bilevel situation...inhale is one pressure and exhale has a slight drop depending on the setting and the force of the breath for Respironics users. 2 distinct pressures...so bilevel is created. The difference between inhale and exhale is called pressure support and it's Pressure Support itself that can trigger centrals in some people...actually a very small percentage of people.
So the idea to turn off exhale relief is just to see if the centrals reduce or not. They may or may not.
I have a friend who gets about 15 to 20 centrals per hour when she uses Pressure Support of 4 (think EPR of 4 if ResMed cpap/apap machines could do 4) but when she uses Pressure Support of 3 her centrals average out to less than 1 per hour. Big difference in the number of centrals just between the 3 PS and the 4 PS.
It's an easy experiment to try....may or may not make any difference at all in the number of centrals but worth at least trying.
Normally exhale relief is simply a comfort feature and causes no problems at all but there is a very small subset of people that find that bilevel itself actually causes centrals....and sometimes all we need to do is find maybe a line where it doesn't...like my friend.
She uses pressure almost as high as yours and she really needs the comfort of exhale relief. We got lucky in that all she had to do was reduce PS from 4 to 3 and the centrals went away and she still was able to use the exhale relief she needs due to pressures in the upper teens.
Re: Continuous Pressure for Central Apnea
Posted: Thu Apr 25, 2019 10:00 pm
by katestyles
Pugsy wrote: ↑Thu Apr 25, 2019 9:56 pm
Kate....
When we use the exhale relief feature it creates a bilevel situation...inhale is one pressure and exhale has a slight drop depending on the setting and the force of the breath for Respironics users. 2 distinct pressures...so bilevel is created. The difference between inhale and exhale is called pressure support and it's Pressure Support itself that can trigger centrals in some people...actually a very small percentage of people.
So the idea to turn off exhale relief is just to see if the centrals reduce or not. They may or may not.
I have a friend who gets about 15 to 20 centrals per hour when she uses Pressure Support of 4 (think EPR of 4 if ResMed cpap/apap machines could do 4) but when she uses Pressure Support of 3 her centrals average out to less than 1 per hour. Big difference in the number of centrals just between the 3 PS and the 4 PS.
It's an easy experiment to try....may or may not make any difference at all in the number of centrals but worth at least trying.
Normally exhale relief is simply a comfort feature and causes no problems at all but there is a very small subset of people that find that bilevel itself actually causes centrals....and sometimes all we need to do is find maybe a line where it doesn't...like my friend.
She uses pressure almost as high as yours and she really needs the comfort of exhale relief. We got lucky in that all she had to do was reduce PS from 4 to 3 and the centrals went away and she still was able to use the exhale relief she needs due to pressures in the upper teens.
Thanks Pugsy. I'm not sure I understand
why it causes centrals, but that is a clear explanation that it
can cause centrals.
Re: Continuous Pressure for Central Apnea
Posted: Thu Apr 25, 2019 10:07 pm
by dee604
Thanks to all for your contributions.
I see there is lots for me to learn.
I can only hope my brain gets the rest it needs to do the necessary learning for optimal self-care.
This forum is an inspiration that there are positive changes ahead for me.
Blessings to each of you....Dee604
- thank you.jpg (26.59 KiB) Viewed 3839 times
Re: Continuous Pressure for Central Apnea
Posted: Thu Apr 25, 2019 10:09 pm
by katestyles
dee604 wrote: ↑Thu Apr 25, 2019 10:07 pm
Thanks to all for your contributions.
I see there is lots for me to learn.
I can only hope my brain gets the rest it needs to do the necessary learning for optimal self-care.
This forum is an inspiration that there are positive changes ahead for me.
Blessings to each of you....Dee604
You can do this, Dee!
Re: Continuous Pressure for Central Apnea
Posted: Thu Apr 25, 2019 10:13 pm
by Pugsy
katestyles wrote: ↑Thu Apr 25, 2019 10:00 pm
Thanks Pugsy. I'm not sure I understand why it causes centrals, but that is a clear explanation that it can cause centrals.
Sometimes bilevel pressures creates a situation where the person breathes in such a manner that they blow off too much carbon dioxide...I call it "wash out".
It's actually carbon dioxide levels in the blood stream that dictate the brain sending the "breathe" signal to the body...not low oxygen like some people think.
So with bilevel the carbon dioxide washes out too soon...doesn't build up to the required level in the blood stream for the brain to wake up and send the "breathe" signal...and when the brain doesn't tell the body to breathe...that's a central apnea. The airway is open but no air is moving because the brain didn't tell anyone to breathe.
Now why bilevel pressures do this for some people...and not the majority of people because remember bilevel is normally the first thing a doctor tries to deal with central apneas....I don't understand the why or how technical mechanics of the exchange of gases that causes this to happen. It's not common though....maybe 1 % of the already small Percent of people who get centrals from cpap/apap therapy.
I have seen it maybe a dozen times here on the forum over the years since we have learned this could happen and machines came about that flagged centrals.
Most recently if you go read AngieLynn's comments about her husband's reports....I am fairly sure that exhale relief was the primary trigger for his centrals.
viewtopic/t175537/Husband-is-More-Tired-with-CPAP.html
We only had the one report from last night turning off EPR...she also dropped the minimum so made 2 changes....so I can't be certain but the drop in number of centrals was significant. We are going to get more data from more nights to make sure....but it sure points to EPR being a significant factor. Might not be the whole factor but I think it plays a big part.
Re: Continuous Pressure for Central Apnea
Posted: Thu Apr 25, 2019 10:19 pm
by katestyles
Pugsy wrote: ↑Thu Apr 25, 2019 10:13 pm
katestyles wrote: ↑Thu Apr 25, 2019 10:00 pm
Thanks Pugsy. I'm not sure I understand why it causes centrals, but that is a clear explanation that it can cause centrals.
Sometimes bilevel pressures creates a situation where the person breathes in such a manner that they blow off too much carbon dioxide...I call it "wash out".
It's actually carbon dioxide levels in the blood stream that dictate the brain sending the "breathe" signal to the body...not low oxygen like some people think.
So with bilevel the carbon dioxide washes out too soon...doesn't build up to the required level in the blood stream for the brain to wake up and send the "breathe" signal...and when the brain doesn't tell the body to breathe...that's a central apnea. The airway is open but no air is moving because the brain didn't tell anyone to breathe.
Now why bilevel pressures do this for some people...and not the majority of people because remember bilevel is normally the first thing a doctor tries to deal with central apneas....I don't understand the why or how technical mechanics of the exchange of gases that causes this to happen. It's not common though....maybe 1 % of the already small Percent of people who get centrals from cpap/apap therapy.
I have seen it maybe a dozen times here on the forum over the years since we have learned this could happen and machines came about that flagged centrals.
Most recently if you go read AngieLynn's comments about her husband's reports....I am fairly sure that exhale relief was the primary trigger for his centrals.
viewtopic/t175537/Husband-is-More-Tired-with-CPAP.html
We only had the one report from last night turning off EPR...she also dropped the minimum so made 2 changes....so I can't be certain but the drop in number of centrals was significant. We are going to get more data from more nights to make sure....but it sure points to EPR being a significant factor. Might not be the whole factor but I think it plays a big part.
This might be what is happening with Dee as well then - Perhaps you should try the same experiment Dee, and turn off your EPR/Flex.
Re: Continuous Pressure for Central Apnea
Posted: Thu Apr 25, 2019 11:33 pm
by palerider
katestyles wrote: ↑Thu Apr 25, 2019 10:00 pm
Thanks Pugsy. I'm not sure I understand
why it causes centrals, but that is a clear explanation that it
can cause centrals.
Briefly, "exhale relief", increases ventilation, by having less pressure on exhale, you're effectively having more pressure on inhale, and that usually causes your Tidal Volume to increase, which increases your ventilation, which will cause you to blow off more co2.
EPR does it more than *flex, number by number (2EPR is a greater pressure difference than 2*flex).
If someone is very sensitive to the level of co2 in their blood, then that extra ventilation/lower co2 can momentarily depress the respiratory drive, and you just won't have any need to breathe for a few extra seconds,.. this can get flagged as a central.
Make sense?
Re: Continuous Pressure for Central Apnea
Posted: Thu Apr 25, 2019 11:35 pm
by palerider
katestyles wrote: ↑Thu Apr 25, 2019 10:19 pm
This might be what is happening with Dee as well then - Perhaps you should try the same experiment Dee, and turn off your EPR/Flex.
It's rare, but it does happen, and turning off EPR/*Flex is an easy way to rule it out.
Re: Continuous Pressure for Central Apnea
Posted: Fri Apr 26, 2019 1:37 am
by ajack
katestyles wrote: ↑Thu Apr 25, 2019 9:51 pm
ajack wrote: ↑Thu Apr 25, 2019 9:38 pm
yes it does reduce exhale pressure. This can cause more CA, so it is said by those that know. so it alters the inhale and exhale pressure. or another way, the inhale pressure stays the same and the exhale drops. either way there is a difference.
I watched the video. It explains that if the flex makes the pressure drop below the pressure needed to hold the airway open, it can increase
obstructive apneas, but I don't see it say it causes centrals.
Perhaps I have the wrong video
Ask on his website, if you wish to. It is on one of his videos, I don't remember which one. General conciseness here and apneabopard seems to confirm this. I also agree with it. You still need to check it out because groups can be wrong and just share misinformation.
I don't know that adding flex/epr causes OA, because it is on the exhale breath. The inhale is still at the treatment pressure for OA. In my case I do obstruct on exhale, so flex,epr or PS is relevant. I need 12cm to hold my throat open on exhale. My inhale starts at 17. You do raise epap on bpap for OA, but that is because you are also raising ipap and keep the same PS. I think it is actually the rise in ipap that clears the OA.
Hypothetically, a person can be on 0.0 exhale and 10cm on inhale and be treated.
Re: Continuous Pressure for Central Apnea
Posted: Fri Apr 26, 2019 11:38 am
by palerider
ajack wrote: ↑Fri Apr 26, 2019 1:37 am
Hypothetically, a person can be on 0.0 exhale and 10cm on inhale and be treated.
This is *completely* and totally wrong.
It is the EPAP that holds the airway open and prevents apnea. If EPAP is too low (which can happen with EPR, possibly with *Flex though it's less likely because *flex raises the pressure at the end of expiration), then the airway can close, and you can't inhale, thus never triggering an increase to IPAP pressure.
Re: Continuous Pressure for Central Apnea
Posted: Sat Apr 27, 2019 12:43 pm
by dee604
Update and another few questions....
Thanks all, for your contributions to my learning.
I do believe my respiratory therapist is on the right track with her adjustments from APAP to CPAP.
My CAs are down from a high of 34 per night on Monday to just 5 last night
As I am still using the loaned equipment and am under the care of the RT, I am reluctant to do any dial a-wagging just yet. Especially as we seem to be making headway.
I'm entirely uncertain if the RT turned off the FLEX/EPR, is there a way to check for that in SleepyHead?
Another question I have is in regard to the image of the first CA of the night.
Does the CA at 1:11:23 even look like a CA?
The flow rate pattern is not consistent with the flow rate of other CAs I have been having.
Thanks again for your input! Dee
Re: Continuous Pressure for Central Apnea
Posted: Sat Apr 27, 2019 1:02 pm
by Pugsy
When Flex is turned on you can usually see 2 pressure lines on the pressure graph. One is inhale and one is exhale.
If you see only one pressure line then Flex is probably turned off.
Re: Continuous Pressure for Central Apnea
Posted: Sat Apr 27, 2019 1:29 pm
by dee604
Sure enough, there are two lines. I'll see what the RT has to say when we meet on Wednesday.
Dee