Just exactly how does the cpap compensate for a change in elevation

[tyrinryan]

The simplest answer, and I'm guessing, is that it provides the specified cm's of pressure greater than the ambient atmospheric pressure ---whatever that happens to be at the moment. So if you move from the coast to mile high Denver or try to use it on a mountain trek or at a ski lodge, you get your specified cm's in addition to the current atmospheric. I don't see how a puny 10 cm's is going to do any good when the general atmospheric pressure drops so significantly with elevation. This thought is on the basis that the current atmospheric pressure is always present and available to at least partially push the soft palate back against the bony part of the throat???

When a low pressure weather system moves through, should you be thinking of increasing the level of cpap??

[palerider]

The simplest answer, and I'm guessing, is that it provides the specified cm's of pressure greater than the ambient atmospheric pressure ---whatever that happens to be at the moment. So if you move from the coast to mile high Denver or try to use it on a mountain trek or at a ski lodge, you get your specified cm's in addition to the current atmospheric. I don't see how a puny 10 cm's is going to do any good when the general atmospheric pressure drops so significantly with elevation. This thought is on the basis that the current atmospheric pressure is always present and available to at least partially push the soft palate back against the bony part of the throat???

You guess right, The pressure sensor in the cpap that measures how much pressure the machine generates against the resistance of the mask vents (and leaks) is measuring against ambient, not absolute, so it doesn't matter what elevation the machine is at, (up to whatever elevation the machine reaches it's fan speed limits and can no longer provide enough pressure due to the less dense air).

When a low pressure weather system moves through, should you be thinking of increasing the level of cpap??

That is counter-intuitive based on your guess above, why would you even think it? Weather changes in barometric pressure are less than altitude changes.

[ChicagoGranny]

This thought is on the basis that the current atmospheric pressure is always present and available to at least partially push the soft palate back against the bony part of the throat???

No. You're intelligent. Think about it.

[tyrinryan]

Thanks Chicagogranny and Palerider for your quick and helpful replies. I feel that I'm making some sort of rookie mistake here. Assuming the atmospheric pressure is approx. 1000 cm's on the coast (sea level) and approx. 850 cm's in Denver {feel free to correct these calculations}, and a person is titrated on the coast for cpap of 10 cm's,---- is not the decrease in atmospheric pressure (on moving to Denver) going to overpower the gain of 10 cm's of cpap support? Further (it's the same question) how about even a small decrease in atmospheric pressure due to a low pressure weather system moving through?

[ChicagoGranny]

current atmospheric pressure is always present and available to at least partially push the soft palate back against the bony part of the throat???

Atmospheric pressure pushes on all sides of the soft palate. It's not going to push anything back.

Think about this. Atmospheric pressure is about 14 lbs. per square inch. The top of your head is maybe 10 square inches. Do you feel like you have a 140-lb. (14 PSI x 10 sq. inches) weight on your head?

Maybe this helps - https://wtamu.edu/~cbaird/sq/2015/09/14 ... g-me-down/

[milboltnut]

The pressure sensor in the cpap that measures how much pressure the machine generates against the resistance of the mask vents (and leaks) is measuring against ambient, not absolute, so it doesn't matter what elevation the machine is at,

sure it does. Elevation plays in.... the air is thinner at higher elevations. So The sensor in the machine will sense less pressure and raise accordingly. This is basic engineering fundamentals. You can debate it all you want Palerider... this is basic. I used to be stationed on a Navy ship with divers in a decompression chamber... they had to decompress form diving in chamber BELOW sea level, which is at higher pressures. SO they had to DE compress, to atmospheric pressure.... which is at sea level pressure.

Air craft Pilots need more 02, why is that?

[palerider]

The pressure sensor in the cpap that measures how much pressure the machine generates against the resistance of the mask vents (and leaks) is measuring against ambient, not absolute, so it doesn't matter what elevation the machine is at,

sure it does. Elevation plays in.... the air is thinner at higher elevations. So The sensor in the machine will sense less pressure and raise accordingly. This is basic engineering fundamentals. You can debate it all you want Palerider... this is basic. I used to be stationed on a Navy ship with divers in a decompression chamber... they had to decompress form diving in chamber BELOW sea level, which is at higher pressures. SO they had to DE compress, to atmospheric pressure.... which is less then sea level pressure.

Air craft Pilots need more 02, why is that?

You have no idea what you're talking about, in relation to CPAP, all of what you're babbling is irrelevant.

[palerider]

Thanks Chicagogranny and Palerider for your quick and helpful replies. I feel that I'm making some sort of rookie mistake here. Assuming the atmospheric pressure is approx. 1000 cm's on the coast (sea level) and approx. 850 cm's in Denver {feel free to correct these calculations}, and a person is titrated on the coast for cpap of 10 cm's,---- is not the decrease in atmospheric pressure (on moving to Denver) going to overpower the gain of 10 cm's of cpap support? Further (it's the same question) how about even a small decrease in atmospheric pressure due to a low pressure weather system moving through?

Why are you asking this, after making the *right* guesses in the first post!

Modern cpaps operate in relation to current ambient pressure, adjusting fan speeds dozens of times per second.

Older cpaps that operated at fixed speeds had altitude *settings*, and had to be adjusted,because they lacked computational power and adequate measurement devices to appropriately measure and compensate for atmospheric pressure changes.

[palerider]

current atmospheric pressure is always present and available to at least partially push the soft palate back against the bony part of the throat???

Atmospheric pressure pushes on all sides of the soft palate. It's not going to push anything back.

Think about this. Atmospheric pressure is about 14 lbs. per square inch. The top of your head is maybe 10 square inches. Do you feel like you have a 140-lb. (14 PSI x 10 sq. inches) weight on your head?

Maybe this helps - https://wtamu.edu/~cbaird/sq/2015/09/14 ... g-me-down/

Exactly, just like an inflated balloon, which will stay exactly the same no matter what the atmospheric pressure is, including altitude changes, or weather.

Only when the *relative* pressure between the inside and outside of the balloon, (throat) changes will there be any effect. That change is the CPAP creating a pressure difference relative to current ambient pressure.

[chunkyfrog]

Uh-oh---it's Saturday . . .

[palerider]

Uh-oh---it's Saturday . . .

Why does "I'm bored" translate into "I'm going to post stupid stuff and waste people's time" for so many?

[Goofproof]

The pressure sensor in the cpap that measures how much pressure the machine generates against the resistance of the mask vents (and leaks) is measuring against ambient, not absolute, so it doesn't matter what elevation the machine is at,

sure it does. Elevation plays in.... the air is thinner at higher elevations. So The sensor in the machine will sense less pressure and raise accordingly. This is basic engineering fundamentals. You can debate it all you want Palerider... this is basic. I used to be stationed on a Navy ship with divers in a decompression chamber... they had to decompress form diving in chamber BELOW sea level, which is at higher pressures. SO they had to DE compress, to atmospheric pressure.... which is less then sea level pressure.

Air craft Pilots need more 02, why is that?

Aircraft Pilots need more O2 because they are pumping more adrenaline, trying to keep from being shot down.. Also at higher altitudes, the air is thinner and has less O2, in a plane that is pressurized, O2 adding isn't needed. Don't let them shoot you down, or put holes in your pressurized plane, you will be fine. Jim

[chunkyfrog]

Uh-oh---it's Saturday . . .

Why does "I'm bored" translate into "I'm going to post stupid stuff and waste people's time" for so many?

I am actually surprised that it's not a lot worse because of the pandemic.
I guess the newly disengaged are too busy trying to be useful to make pests of themselves.

[milboltnut]

The pressure sensor in the cpap that measures how much pressure the machine generates against the resistance of the mask vents (and leaks) is measuring against ambient, not absolute, so it doesn't matter what elevation the machine is at,

sure it does. Elevation plays in.... the air is thinner at higher elevations. So The sensor in the machine will sense less pressure and raise accordingly. This is basic engineering fundamentals. You can debate it all you want Palerider... this is basic. I used to be stationed on a Navy ship with divers in a decompression chamber... they had to decompress form diving in chamber BELOW sea level, which is at higher pressures. SO they had to DE compress, to atmospheric pressure.... which is less then sea level pressure.

Air craft Pilots need more 02, why is that?

You have no idea what you're talking about, in relation to CPAP, all of what you're babbling is irrelevant.

sure I do.... if i didn't, I'm sure you would set met straight right? Maybe you should tweek your machine a little bit more... you seem edgy today

[palerider]

The pressure sensor in the cpap that measures how much pressure the machine generates against the resistance of the mask vents (and leaks) is measuring against ambient, not absolute, so it doesn't matter what elevation the machine is at,

sure it does. Elevation plays in.... the air is thinner at higher elevations. So The sensor in the machine will sense less pressure and raise accordingly. This is basic engineering fundamentals. You can debate it all you want Palerider... this is basic. I used to be stationed on a Navy ship with divers in a decompression chamber... they had to decompress form diving in chamber BELOW sea level, which is at higher pressures. SO they had to DE compress, to atmospheric pressure.... which is less then sea level pressure.

Air craft Pilots need more 02, why is that?

You have no idea what you're talking about, in relation to CPAP, all of what you're babbling is irrelevant.

sure I do.... if i didn't I'm sure you ego would ramble more BS

It's a waste of time to respond to ignorance on the level you exhibit.

Since you're incapable of comprehending what's already been said, and you're just trolling along AS USUAL, wasting everyone's time... nuff said.