Why should I have a minimum air pressure?

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daisy56
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Why should I have a minimum air pressure?

Post by daisy56 » Sat Jan 28, 2012 11:00 pm

How important is the minimum air pressure number? Mine is set to 6 right now and seems fine I guess..not sure what it is I want with that number. I know my maximum number is set to 12 and so far I haven't gone pass 11 during my sleep. But my question is why and how do I know if I should set my number to a lower number...the reason I'm asking is because I wondered if I am able to be comfortable at a lower number, like 4 or 5... wouldn't I WANT to set it to that? In other words, why would we want more air pumping into us that is really not needed, I feel like I'm making myself more dependent on it or forcing myself to need more air when or if I really don't need it.....I HOPE I have made sense with my question.. Lol


Thank you in advance so very much. I get these questions in my head and it bothers me so much until I understand.
I'm dealing with Tinnitus (ringing in ears after a sudden moderate hearing loss this past October) so I have been on a chat forum more for this condition than I have been on this sleep apnea site. I need to take time to read more on here and learn more by reading, but I was diagnosed with sleep apnea and Tinnitus in the same month and it has been a real struggle...Thank you for soooooooo very much for answering my random questions.
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Mr Bill
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Re: Why should I have a minimum air pressure?

Post by Mr Bill » Sat Jan 28, 2012 11:34 pm

The minimum is the minimum you need to keep the airway open and its lower to make it easier to exhale. If it is set too low you will feel like you are sucking hard on a tiny straw for air. Pugsy will probably have a better universal definition.

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Re: Why should I have a minimum air pressure?

Post by Muse-Inc » Sun Jan 29, 2012 1:58 am

As Mr Bill stated, the minimum is what is needed to keep your breathing stable and apnea and hypopnea events from occurring. You don't become dependent other than this is the amt of pressure you need to maintain stable breathing & minimal events while you are asleep. Many of us find that 6 is not sufficient pressure as we have sensations of suffocating, you on the other hand may be fine with 6 as your minimum -- pressure needed is unique to our particular airway.

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Re: Why should I have a minimum air pressure?

Post by robysue » Sun Jan 29, 2012 2:14 am

daisy56 wrote:How important is the minimum air pressure number? Mine is set to 6 right now and seems fine I guess..not sure what it is I want with that number. I know my maximum number is set to 12 and so far I haven't gone pass 11 during my sleep. But my question is why and how do I know if I should set my number to a lower number...the reason I'm asking is because I wondered if I am able to be comfortable at a lower number, like 4 or 5... wouldn't I WANT to set it to that?
In general the min pressure number for an APAP needs to be high enough to be effective at keeping your airway open much of the time---as in at least 50 or 60 percent of the night. If the min pressure is too low, then even with an APAP, the pressure adjustment might not be fast enough to really keep the nastiest of your clusters under control.

For many people on the board, that means that the min pressure setting on an APAP needs to be within 2 or 3 cm of what their long-term 90% pressure reading is. In other words, many people with a 90% pressure reading of 10cm often find that the machine does a better job overall of controlling their apnea (and hence letting them sleep), if the min pressure is around 7 or 8 cm.

But---if you're not getting nasty clusters caused by the machine not ramping up fast enough AND if you're comfortable breathing at 6cm, there's no good reason to increase your min pressure just because others find they need to do so.

As for further reducing the min pressure to 4 or 5 cm. Well, the lower that min pressure, the longer the machine takes to get the pressure up to 10cm in response to your events. That may or may not be a problem, but it is worth considering. And then there's the problem that if your min pressure is set to 4 or 5 cm, sealing the mask is easy at the beginning of the night, but once the pressure gets up near 10cm, there's a real chance that leaks will start. Sealing the mask at the beginning of the night needs to be at pressures that are "close enough" to the maximum pressure that you might need during the night---where "close enough" typically means no more than about 4 or 5 cm below the expected maximum pressure.

As for comfort: There are some of us who are quite comfortable breathing with our machines set to minimum pressure levels---and often we also have rather low therapeutic pressure settings to begin with. But for many people whose therapy pressure is regularly above 8 or 9cm, trying to breathe at 4 or 5cm can cause comfort problems---they'll describe the feeling as not getting enough air in through the mask or say that it makes them feel as though they are suffocating or breathing through a straw. Such feelings are often a major sign that the person is fully adjusted to breathing against their therapy pressure.
In other words, why would we want more air pumping into us that is really not needed, I feel like I'm making myself more dependent on it or forcing myself to need more air when or if I really don't need it.....I HOPE I have made sense with my question.. Lol
Keep in mind that the main problem with "too much air being pumped in" is aerophagia for those of us unlucky enough to suffer from it. The air being pumped in is just plain old room air so you're not going to become "dependent" on it in the sense of some kind of addiction.

And some other things to keep in mind:

1) Your diaphragm actually has to work a tiny bit harder with additional air pressure because exhaling against the pressure is a tiny bit harder than just exhaling against ambient air pressure. And the higher your prescribed therapy, the harder your diaphragm has to work.

2) The APAP does NOT force you to breathe like a ventilator does. And hence the pressurized air from the APAP does NOT weaken your lungs or the muscles you use to breath. All the pressurized air does is make it physically much harder for your upper airway to collapse and close during the night.

3) At its maximum pressure setting of 20cm H20, the added pressure is about the difference between the ambient pressure on a bright sunny, "high air pressure" day and a dark and stormy "low air pressure" day. In other words, even if your APAP were set to maximum pressure, you are breathing against pressures that are pretty much "normal" as far as our bodies are concerned. This is also why we get used to breathing with the machines and eventually don't really notice our pressure all that much. (And hence the reason so many of us stick our hand in front of the vent when we wake up just to make sure the mahcine is still on.)

4) Yes, many of us do feel like we become dependent on the machines. But the dependence is not a physical dependence in the sense that we can't breathe without the additional air. The emotional/psychological dependence comes from our brains and bodies realizing just how much better it feels to sleep without the constant battle with the apneas. I'll use myself as an example: Pre-CPAP I never consciously woke up with to a feeling of choking or not being able to breath because of my apneas and hypopneas---indeed, my problem was primarily with "hypopneas with arousal"---my body would arouse itself just enough to restart the breathing before any serious O2 desats occurred and these arousals were not long enough for me to remember the next morning. Now? If I accidentally fall asleep on the couch or in the recliner without my BiPAP, I find that I do startle myself awake with a feeling my breathing is just not right. My brain and body both resent having to arouse to restart the breathing over and over and over now. And it's not that my body is physically dependent on the air being pumped into my lungs that causes this problem----it's that my body and brain resent being expected to wake up every few minutes when trying to sleep. And since it's no longer normal for my body to have to do this when I'm sleeping, the arousals from the hypopneas are much more likely to cause me to arouse all the way to WAKE than they did pre-PAP.
Thank you in advance so very much. I get these questions in my head and it bothers me so much until I understand.
I'm dealing with Tinnitus (ringing in ears after a sudden moderate hearing loss this past October) so I have been on a chat
forum more for this condition than I have been on this sleep apnea site. I need to take time to read more on here and learn more by reading, but I was diagnosed with sleep apnea and Tinnitus in the same month and it has been a real struggle...Thank you for soooooooo very much for answering my random questions.
It's a bummer about the Tinnitus. I've suffered from it most of my life. Fortunately for me, most of the time mine is not painful and is pretty easy to ignore. One thing that works for me is always trying to have some verry,very soft background noise around. The background noise can be white noise, nature noise, or very, very soft music, but I need to keep the volume really low---the idea is not to drown out the tinnitus, but rather give it some competition for my brain's attention.

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Re: Why should I have a minimum air pressure?

Post by teknomom » Sun Jan 29, 2012 9:38 am

I love it when people just HAVE to understand their therapy. I feel the same way. Keep asking questions! Sorry about the Tinnitus and thanks to robysue for the suggestion about white noise. I'll try it, too.

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Re: Why should I have a minimum air pressure?

Post by daisy56 » Sun Jan 29, 2012 12:52 pm

Thank you MrBill and Muse-inc, robysue and teknomom! WOW, wow, wow is all I can say...you all explained it sooo very well.
I cant tell you how much better I feel now just understanding this more. I was surprised to learn all this. robysue, you have eased my concerns a great deal. I wondered..no I Obsessed over wondering if my muscles or lungs would become weaker being dependent on this air over time, and you cleared that right up, THANK YOU for all your information so very much. I'm sorry robysue and teknomom that you have 'T' as well. I have been using a fan at night so far, but haven't bought any nature sound cds like I want as of yet...I want to finally get my sleepyhead going before anything else. I don't have the piece I need for my computer yet to be able to download this, errrr.

teknomom, please join me and many wonderful people on https://www.facebook.com/AmericanTinnitusAssociation if you have Facebook. We cry, vent, laugh and exchange many coping ideas on there, they have been there for me since day one.

robysue, you mentioned that you mostly just had "hypopneas with arousal", if I remember correctly that is what my Doctor said I was dealing with, like 40 and hour. Again Thank you sooooooooo much, I learned soo much from you!!!
Lord help me to remember that nothing is going to happen to me today that you and I together cant handle.

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Re: Why should I have a minimum air pressure?

Post by archangle » Sun Jan 29, 2012 2:03 pm

Don't worry about it too much if it's working for you.

Slight simplifications follow.

The machine doesn't increase pressure immediately. If the minimum pressure is too low, you will have some degree of apnea after you fall asleep until the machine increases the pressure up to the level that keeps your airway open. My machine seems to want to only go up 1 pressure point per minute. Repeat the cycle for every bathroom break.

The machine will slowly drop your pressure if you stop having apneas. You may breathe fine on your own for part of the night and your auto pressure can drop. When your apneas start again, you have to suffer from apnea until your pressure comes back up.

If you put your mask on at a low pressure and adjust it to not leak, it may start leaking if your pressure goes up. Mask fit is easier with a smaller pressure range.

Lots of people feel they're suffocating if the pressure is too low, even if they're still awake. This is sort of funny because you don't feel you're suffocating with 0 pressure without the mask, but it happens.

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daisy56
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Re: Why should I have a minimum air pressure?

Post by daisy56 » Sun Jan 29, 2012 4:31 pm

archangle, thanks! You and someone else said this - "If you put your mask on at a low pressure and adjust it to not leak, it may start leaking if your pressure goes up. Mask fit is easier with a smaller pressure range" - I'm trying to sit here and read this over and over till I get it, but my brain wont work! lol If you feel like it, could you explain this again as if you were talking to a 3rd grader this time, . Again, someone else mentioned this too and I so desperately want to understand this.

Thanks!!
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Re: Why should I have a minimum air pressure?

Post by kteague » Sun Jan 29, 2012 5:14 pm

Hello and welcome. About your pressure range... Have you ever been in the middle of a game - any kind of game - and someone changed the rules and it messed up your strategy? Well, if you put your mask on and it's sealing well at the lower end of your pressure range, once your pressure increases a lot, your mask (if it could talk) would probably shout, "Hey, don't change the rules in the middle of the game - I'm not prepared for that!" Yes, it is ideal to use only the pressure needed for effective treatment, but if you put your mask on at a pressure way lower than it is going to be asked to perform at, it may be too much of a rule change for it to handle without leaking.

Others have already talked about the time it takes a machine to incrementally climb to an effective pressure. If a pressure range was smaller or more narrow (as in maybe 8-12 just for an example), the time to reach effective pressure is quicker and the changes asked of the mask in performance are less dramatic.

Did I just make the water muddier? lol

Again, welcome.

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Re: Why should I have a minimum air pressure?

Post by chunkyfrog » Sun Jan 29, 2012 6:02 pm

I am curious if many others find the sound from their machine provides any relief from tinnitis.
To quote my very first post on this forum,
". . . sounds from my machine . . . drowns out my tinnitis very nicely."

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Re: Why should I have a minimum air pressure?

Post by daisy56 » Sun Jan 29, 2012 7:01 pm

kteague, you explained it perfectly. Thank you so much I think the reason I was confused too was because I was thinking if the mask is fairly snugged on a lower setting, why or how could there be more chance of a leak happening once the air pressure goes up to a higher number during sleep...thinking this would only make the mask tighter once the air is blowing harder.... BUT now I think I realize what you mean - the leaks your describing are leaks as in 'APNEAS', right?? Meaning I should get closer in range to avoid anymore leaks (apneas) from happening...right?? Lol, if you still talk to me after this one, I declare you my best friend!

Chunkyfrog, so funny you should say that!! My machine actually does not make noise like the older models, BUT
for some reason it feels like once I take off the nasal mask, I notice my Tinnitus more!! I don't understand it, one because my machine is quiet, and two my ringing is very annoying! errrr. Something else I noticed, sometimes when I swallow with the mask on, I can hear/feel the air against the inside of my eardrums....hahahaha, I really don't know if thats even possible, but it feels like it! It kind of worried me.....but I'm not too worried, soooo
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Re: Why should I have a minimum air pressure?

Post by ems » Sun Jan 29, 2012 7:47 pm

chunkyfrog wrote:I am curious if many others find the sound from their machine provides any relief from tinnitis.
To quote my very first post on this forum,
". . . sounds from my machine . . . drowns out my tinnitis very nicely."
Happily, no noise from my machine... but the white noise machine that I purchased recently does the same thing. It's a very calming, soothing sound (to me), and helps with the "T" as well as any outside noises.

Edit: CF... just realized we have the same machine. I'm surprised to read yours makes any noise at all... mine doesn't. Well, not exactly, but I had yours before I was switched over to BPAP, and it didn't make any noise either.
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Re: Why should I have a minimum air pressure?

Post by Mr Bill » Sun Jan 29, 2012 10:46 pm

daisy56 wrote:kteague, you explained it perfectly. Thank you so much I think the reason I was confused too was because I was thinking if the mask is fairly snugged on a lower setting, why or how could there be more chance of a leak happening once the air pressure goes up to a higher number during sleep...thinking this would only make the mask tighter once the air is blowing harder.... BUT now I think I realize what you mean - the leaks your describing are leaks as in 'APNEAS', right?? Meaning I should get closer in range to avoid anymore leaks (apneas) from happening...right?? Lol, if you still talk to me after this one, I declare you my best friend!

Chunkyfrog, so funny you should say that!! My machine actually does not make noise like the older models, BUT
for some reason it feels like once I take off the nasal mask, I notice my Tinnitus more!! I don't understand it, one because my machine is quiet, and two my ringing is very annoying! errrr. Something else I noticed, sometimes when I swallow with the mask on, I can hear/feel the air against the inside of my eardrums....hahahaha, I really don't know if thats even possible, but it feels like it! It kind of worried me.....but I'm not too worried, soooo
Once you get your software going you will see a leak line in the software. Your mask is constructed so it must leak all the time to let your exhaled breath out. You can feel that breeze if you hold your hand in front of your face. If, however, you have mask seal leaks around the edges, they are usually audible and if they are significant you will see them show up in your leak line. Don'' make the mistake of making your mask too tight. Set your machine for the upper pressure and loosen your mask till it almost starts to leak. The seals are made to expand against your face and so the mask does not need to be on that tight. Once you get it set, then pull your mask off over your head instead of undoing the straps. Once you have it right, you hardly need to adjust it ever.

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Re: Why should I have a minimum air pressure?

Post by kteague » Sun Jan 29, 2012 11:46 pm

Ha ha, your sense of humor is a welcome relief. There is a term used around here for some mask leaks - mask farts. (for obvious reasons) A mask leak is when air that should be going down your throat escapes around the edges of the mask. The higher one's pressure, the greater the liklihood in some masks that they will leak air. Now, every mask has some air escaping from its vents, as they are designed to vent exhaled air. But if a lot of air escapes other than at the vent, your treatment could be compromised. And if the leaks are too great, your data may not be reliable. Your data from your machine can tell you if your leaks are in an acceptable range.

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Re: Why should I have a minimum air pressure?

Post by Pugsy » Sun Jan 29, 2012 11:50 pm

Yep. Some masks fart and some masks whistle.. Mine doesn't fart but if the nasal pillows aren't seated properly I get this annoying whistle until I get them properly situated. I know it really isn't a loud whistle but in the middle of the night when all else is quiet, it sounds as loud as a train whistle.

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