Altitude equivalent of CPAP pressure

socks349 · Post by **socks349** » Fri Jun 19, 2009 7:27 pm

I'm sure there's a table somewhere, but how does CPAP pressure correspond to altitude. For instance if my CPAP machine is set to 10 cm and I live at sea level, what is the corresponding pressure at 6,000 ft? I know many machines have auto compensation, just trying to get a feel for what 10 cm means relative to altitude.

jdm2857 · Post by **jdm2857** » Fri Jun 19, 2009 8:01 pm

Atmospheric pressure at sea level = 1 atm = 14.7 lb/square in = 1034 cm H20 (approx.)

So a CPAP pressure of 10 cm H20 is about 1% of atmospheric pressure.

Wulfman · Post by **Wulfman** » Fri Jun 19, 2009 8:01 pm

If you have the REMstar Pro 2 (as listed in your profile), it DOES have altitude compensation.
Rule of thumb......
All of the "data-capable" machines in the Respironics and ResMed lines have altitude compensation......and probably most of the other manufacturers lines, too.
Non-data-capable machines do not have that feature and have to be manually adjusted.

Den

timbalionguy · Post by **timbalionguy** » Fri Jun 19, 2009 8:34 pm

Note that pressure, given in inches of water, is the same at any altitude. What is different is the absolute pressure. So, if a machine references its output pressure to the local ambient atmospheric pressure with a sensor, you will get good numbers. Very simple machines, without pressure sensors cannot do this. Auto-adjust machines have to do this. I would guess, as has been stated earlier, any data-capable machine should be able to do it.

Look in the specifications on CPAP.com. It gives (for the machines I looked at) the altitude range over which the machine can compensate.

Goofproof · Post by **Goofproof** » Fri Jun 19, 2009 8:41 pm

The added pressure of XPAP treatment would be more like going down in alt, as the pressure is increased by XPAP. It means nothing, as XPAP treatment works on a pressure differental of the pressure in the airway being more than the pressure on the body, forcing the airway open. Jim

jdm2857 · Post by **jdm2857** » Fri Jun 19, 2009 9:00 pm

Absolute air pressure does change with altitude. It is due to the weight of air above, and at higher altitudes there is simply less air above.

It just like being underwater. The deeper one goes, the higher the pressure.

At 6000 ft. above sea level atmospheric pressure drops to .80 atm = 11.8 lb/square in = 830 cm H20.

Physics class dismissed.

Altitude equivalent of CPAP pressure

Altitude equivalent of CPAP pressure

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