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What does CPAP pressure really do?
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PaulaO2 Offline
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Post: #1
What does CPAP pressure really do?
So I was thinking (I know, bad habit) about how an obstructive apnea event happens. The muscles in the throat are voluntary so when we relax in sleep, they do too.

And we also know that a normal CPAP set to 20cmH2O does not have enough umph to blow up a balloon. We know that it does not inflate our lungs like a ventilator can.

So if it cannot blow up a balloon, then how does it open the airway? Those muscles must weigh a lot, especially for those of us who are obese and have the added fat to lift.

Does the pressure actually force the airway open?

OR does it cause some sort of stimulation that makes us open it on our own without us realizing we are doing it?

PaulaO2
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Breathe deeply and count to zen.

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
01-21-2013 02:41 PM
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Shastzi Offline

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Machine: ResMed S9 Autoset
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Post: #2
RE: What does CPAP pressure really do?
That would be a good project for someone with a bronchio scope and sensitive manometer to play with.
All I know is that I go into O2 desaturation events without a certain amount of minimum pressure.

Wink
01-21-2013 03:30 PM
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SPOUSE Offline

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Post: #3
RE: What does CPAP pressure really do?
Looks like "Genes" posted a pretty good explanation back in October. Search "how does cpap machine work".




(01-21-2013 02:41 PM)PaulaO2 Wrote:  So I was thinking (I know, bad habit) about how an obstructive apnea event happens. The muscles in the throat are voluntary so when we relax in sleep, they do too.

And we also know that a normal CPAP set to 20cmH2O does not have enough umph to blow up a balloon. We know that it does not inflate our lungs like a ventilator can.

So if it cannot blow up a balloon, then how does it open the airway? Those muscles must weigh a lot, especially for those of us who are obese and have the added fat to lift.

Does the pressure actually force the airway open?

OR does it cause some sort of stimulation that makes us open it on our own without us realizing we are doing it?
01-21-2013 06:05 PM
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Sleepster Offline
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Post: #4
RE: What does CPAP pressure really do?
The CPAP machine doesn't blow up your lungs like a balloon. Your diaphram pulls downward lowering the pressure inside your lungs so the atmosphere can push its way in. The problem with OSA is that the entryway to the lungs collapses so that the diaphram can't pull the air in. The CPAP machine inflates the airway solving the problem.

It is amazing how little pressure it takes to do this in the vast majority of cases.

In extreme cases CPAP machines cannot deliver enough pressure to open the airway. The only options available at that point are surgery. In the most extreme cases that surgery is the dreaded tracheotomy. New robotic surgeries offer an alternative to many of these people.

Sleepster
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
01-21-2013 06:26 PM
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archangle Online
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Post: #5
RE: What does CPAP pressure really do?
My understanding is that it's purely mechanical inflation of the airway.

Imagine if the hose on your CPAP was made of thin leather like the leather on the fingers of a glove. It also doesn't have the spiral spring that most CPAP hoses have. Now, disconnect from the CPAP and run the leather hose across the table. Lay some raw steaks on top of it. Now, imagine putting the end in your mouth and trying to inhale through it. The hose would probably collapse, blocking off airflow.

Now, hook up the CPAP machine, turn it on, and it will inflate the leather hose and let air flow through.

In some ways, your airway is sort of like a floppy leather tube with meat around it.

Actually, I believe it's only the area around the back of your nose and mouth that are floppy like this, but the idea is valid. The flexible parts of your airway flop closed and a little extra air pressure can inflate the collapsed area and let air flow through.

Get the free SleepyHead software here.
Useful links.
Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
01-21-2013 08:51 PM
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PaulaO2 Offline
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Posts: 8,068
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Machine: S9 Autoset
Mask Type: Full face mask
Mask Make & Model: F&P Simplus
Humidifier: H5i
CPAP Pressure: 14-20
CPAP Software: SleepyHead

Other Comments: Ehlers-Danlos Syndrome, Hypermobility Type; chronic sarcasm

Sex: Undisclosed
Location: western NC, USA

Post: #6
RE: What does CPAP pressure really do?
Gross but for a visual person like me, I can see it exactly. Thanks!

Of course the lungs have not just the muscle of the diaphragm, but also the weight of the ribs and a much larger area. The throat is a very small space comparatively.

PaulaO2
Apnea Board Moderator
www.ApneaBoard.com


Breathe deeply and count to zen.

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
01-21-2013 09:48 PM
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archangle Online
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Advisory Members

Posts: 3,159
Joined: Feb 2012

Machine: ResMed S9 AutoSet
Mask Type: Nasal pillows
Mask Make & Model: ResMed Swift FX
Humidifier: ResMed S9 H5i
CPAP Pressure: 16-20
CPAP Software: ResScan SleepyHead EncoreBasic

Other Comments: Happy PAPper

Sex: Undisclosed
Location: USA

Post: #7
RE: What does CPAP pressure really do?
(01-21-2013 09:48 PM)PaulaO2 Wrote:  Gross but for a visual person like me, I can see it exactly. Thanks!

Of course the lungs have not just the muscle of the diaphragm, but also the weight of the ribs and a much larger area. The throat is a very small space comparatively.

I tried to think of something less gross than steak to use as an example, but couldn't figure out something that would convey the idea as well.

While I was thinking about it, I realized that most of the windpipe actually does have rings of cartilage or something to keep it from collapsing. You can sort of feel this in your neck. I never realized why that was there before.

At least, I think that's the way the windpipe is.

Get the free SleepyHead software here.
Useful links.
Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
01-22-2013 02:42 AM
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