(03-26-2012, 08:13 PM)acc Wrote: I have had my machine for 9 months and working great. We are getting ready to go on vacation for three weeks in China, 4 days I will be using the CPAP at 14,000ft. altitude (Tibet). I cannot get any input on what I should adjust the machine to. ResMed tech support only says machine has only been tested to 8500 ft. Doctor's staff says continue to use machine (duh?). I read online that increases the pressure range will solve the problem, but I don't know how much to adjust. Any help will be appreciated. Also, I will be taking Diamox to prevent altitude sickness--, but dosage changes depending on who you talk to. No one I have talked with has experience with this altitude and CPAP machine.
I have the information on how to change pressures, but have never messed with the set up of the machine.
acc
I recommend that you take personal responsibility for your own health, and not depend too heavily on secondhand opinions.
Your Autoset might autoadjust just fine at 14K feet. You wrote that it had simply not been tested, and that it worked fine from zero to 8.5K feet. Why would it break down, necessarily from 8.5K to 14K?
I am skeptical that the max presssure needs to be increased. I don't see the reason, and no one here has provided a rationale for why the pressure should be increased. Just some place said so, without explaining why.
Contrary to this opinion of some hospital, I can imagine why high altitude might reduce obstructive apnea, and thus one could reduce their max pressure. At sea level, atmospheric pressure presses all over our body, including our neck. Without a PAP device, the pressure is also applied to the inside of our airway, hence no difference inside or out. Put on a PAP however, and the external pressure presses in, and the internal pressure presses out, and the internal pressure is the sum of atmospheric pressure plus your PAP pressure; thus your PAP inflates your airway due to this differential pressure from your PAP machine.
Increasing the altitude will not affect the differential pressure, but it will reduce the absolute pressure on the outside of your neck, so it is going to expand more. Exactly as a weather ballon expands as it ascends because it is moving into a lower pressure zone. So the need for PAP might decrease as altitude increases.
Another thing to consider is leakage. Increasing pressure at sea level causes mask leakage to increase, and this is under the fairly high atmospheric pressure at sea level that presses on the outside seal of our masks, thereby helping the seal contain the internal pressure from the PAP. Removing this helpful external pressure from most of the atmosphere by going to high altitude is surely going to increase leakage, because now the mask seal has to do all of the work because the atmosphere is not helping so much pressing on the seal from the outside.
So I think your mask is going to leak like a sieve if you leave the pressures unchanged and go to 14K. And if you increase your max pressure, then I think it will almost blow the mask off of your face. I exaggerate, of course, to make the point, but I do strongly predict your mask will leak like crazy if you both increase the internal pressure and decrease the external pressure by going to high altitude. I think this is just common sense.
I strongly suggests that you experiment extensively while fully awake during the day time with your equipment, starting with your Mask Fit test, which you access by holding down the SET button for a few seconds. This simple test will tell you immediately if your mask leaks more because you have gone to high altitude.
Also, ask some pilots about pressure changes, and how altitude will affect things such as mask leakages. Pilots have very direct common sense explanations of these things.
I strongly recommend that you get the Sleepyhead software from the forum archive here, and install it asap to learn how to read the pressures, leakages, and the various components of AHI particularly the Obstructive apnea and hypopneas. This software will give you the data it takes to see what is happening with changes in atmospheric pressure.
Let me know if this helps.
My age is none of my mind's business. --- Netskier
