(03-27-2012 11:42 AM)PaulaO2 Wrote: I didn't provide a link because I wasn't sure if the site was commercial or not. I looked at the site better today and it is the forum from the American Sleep Apnea Association. A simple Google search on "CPAP at high altitude" gave me the link. I don't post information that is incorrect or if I am uncomfortable with their statements.
(I had the link to the thread here but this forum software changed it to be ***. Do a Google search and it should be fairly high up the result list)
Quote:I posted a question several months ago about using a CPAP at high altitudes, and I finally have some information to share. A little background: I use a CPAP and live in Denver, CO (the mile high city) and the manual for my CPAP says that on the highest altitude setting the machine is good for 7500 feet. I'm traveling to Peru and Bolivia in April and will be at altitudes ranging from 8500 feet to 13000 feet.
I called the Lung Line at National Jewish Hospital (http://www.nationaljewish.org). National Jewish is the #1 respiratory hospital in the US, and I'm fortunate that it's located here in Denver. Lung Line is at 800-222-LUNG, a free service where registered nurses can answer questions about respiratory issues from 8 am to 4:30 pm Mountain Time (2 hours earlier than Eastern time). I was referred to another number and after a couple of weeks, someone returned my call.
An adjustment in pressure is called for when using a CPAP high altitudes, and I'll be going in to see someone to learn about how to make those adjustments in the near future. Specifically, an increase in pressure is required. The woman I spoke with was able to calculate what my pressure would need to be at three specific altitudes where I'll be spending nights. The adjustments needed aren't huge. My normal pressure is 6 (cm h2o), and the highest the pressure will need to be - for 13,000 feet - is 7.5.
I hope this information is helpful...
Further down the posts are some links that should be valid enough.
http://chestjournal.chestpubs.org/content/108/6/1577.abstract - the short version
http://chestjournal.chestpubs.org/content/108/6/1577.full.pdf - the full version
Of particular interest to those of us who do not understand journal articles is page 5 with the Discussion and Conclusion.
The article you cited does not say that one must increase the pressure if your machine autoadjusts for altitude. The article says that you must increase for altitude unless your machine does so automatically.
And, acc stated that the machine being used for the trip is a Resmed S9 Autoset which does autoadjust for altitude.
You cited http://chestjournal.chestpubs.org/content/108/6/1577.abstract
, the conclusion of which states:
"Conclusions: Altitude significantly alters delivered pressure according to predictions made by the fan laws, unless a unit has pressure-compensating features.
Clinicians should consider this factor when CPAP is prescribed for patients who live or travel to places located at significantly higher or lower elevations than the titration site."
I boldfaced parts for emphasis.
You cited the full paper http://chestjournal.chestpubs.org/content/108/6/1577.full.pdf
which states: "Conclusions.
The delivered CPAP of noncompensating devices is significantly affected by changes in altitude. Pressure sensor-equiped devices maintained delivered pressure throughout the altitudes simulated in the present study."
I hope this helps.
P.S. I heard someone on Sunday report that the Rand Corporation did a study that found that Physicians diagnoses are correct 55% of the time, and wrong 45% of the time. Thus, they are only slightly better than chance. Given this, I conclude that we should be very skeptical of their opinions, and should take personal responsibility for our own health whenever we can.
I think the nurse on the phone was wrong.
P.S. 2. The study was published 19 yrs ago, so the work was done at least 20 yrs ago, so it is not current.
P.S. 3. I am sticking with my original analysis. I think that altitude may lessen obstructive apnea provided that the machine really delivers the selected pressures. This is because the proportion of total air pressure being delivered to the airway from the PAP device increases as altitude increases, since the external ambient air pressure is decreasing, and will go to zero if you go into space. So as you go up, it is as if your neck is being sucked on from the outside, so less compression from the outside, and finally expansion to the outside. Plus, on the inside the relative pressure is increasing, relative to the outside, so more expansion from the inside of your airway.
I think I read that astronauts will explode from their internal body pressures if their pressurized space suits lose their pressures. Therefore airways should expand as we move toward space without wearing pressurized space suits (and hold our breath as we do this).