Is CPAP the equivalent of moving 500 feet lower??

[Reznik]

So, just for fun, I decided to compare how much pressure a CPAP adds compared to the existing atmospheric pressure at various altitudes.

The internet tells me that 

1. At 0 feet above sea level, atmospheric pressure is 1033.3 cm2 of h20.
2. At 500 feet above sea level, atmospheric pressure is 1015 cm2 of h20.
3. At 1000 feet above sea level, atmospheric pressure is 956 cm2 of h20.

I live at about 800 feet above sea level.  But, for simplicity sake, let's just say that I live at 500 feet above sea level.

I use a CPAP at night set to 8cm2 of h20.  That means that I receive the atmospheric pressure (1015) plus the additional pressure from my CPAP (8), for a total of 1023 cm2 of water in atmospheric pressure while I sleep.

Couldn't I accomplish the same thing by moving to a location that was at sea level?  That would get me air pressure equal to 1033.3 cm2 of water, which is 18 cm2 of water more pressure than I get while sleeping at 500 feet of sea level.  That's 10 cm2 of water more than I'm getting now with my CPAP.

Am I missing something here?  If so, what is it?

[CB91710]

While lower elevations can help, this is primarily due to the improved O2 saturation. You won't see a difference in <1,000ft of elevation change. 5000ft, maybe improved O2 sat, probably only a minor change in AHI.

CPAP is effective because of the differential pressure between your airway and ambient pressure.
The pressure from the machine basically "inflates" your throat and upper airway.

[Walla Walla]

Not that it matters as Rich pointed out. But another problem with dealing with atmospheric pressure is that it's not a static number. The pressure is in a state of flux which is why you have high pressure and low pressure weather systems.

[Moriarty]

Am I missing something here?  If so, what is it?

G’day Reznik

What CB91710 said.


Cheers

David

[OMyMyOHellYes]

Nope.

Faulty assumptions that CPAP treatment is about absolute pressure or that the pressure provided by CPAP somehow increases O2 saturation. It doesn't. The only purpose of CPAP is to mechanically keep the throat open so a person can breathe. It treats the throat/airway like a balloon. It inflates it to hold it open.

CPAP works on the differential air pressure in relation to ambient air pressure, not an absolute pressure.

[VladimirTrotzskyi]

CPAP is effective because of the differential pressure between your airway and ambient pressure.

This, exactly.

[Reznik]

That's what I thought. Thanks everyone!