Operating altitude of S9 Auto

[popotla]

Resmed state that the S9 auto can be used up to an altitude of 2591 meters above sea level. This doesn't fit my travel plans!

What happens above 2591 meters?

[Sludge]

It depends on the type and extent of your SBD, and how quickly and high you ascend.

You could end up with a pile of altitude-induced central apneas and/or periodic breathing.

[TheDuke]

I have used an old Respironics BiPAP Plus at 11,000 feet elevation (3353 meters) for a span of several weeks with no ill effects of any kind. I was in a room with normal 115 Volt AC service. I slept well, and apparently my machine survived without any sort of damage. The manual stated that it has automatic altitude compensation for up to 5600 feet, and I was at almost twice that elevation. My pressure settings were BiPAP mode ,14/10 and I was using the Respironics heated humidifier.. I don't know what elevation you expect to sleep at, but I believe that the machine will keep you quite comfortable.

TheDuke

[archangle]

It depends on the type and extent of your SBD, and how quickly and high you ascend.

You could end up with a pile of altitude-induced central apneas and/or periodic breathing.

Good info, but I presume that's an effect of altitude on your body. I wonder what happens to the CPAP machine. Does it fail to maintain the correct differential pressure, overheat, or become sentient and try to suffocate you?

[Sludge]

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2864887/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3837559/

http://journal.publications.chestnet.or ... 5/1577.pdf

[Sludge]

I wonder what happens to the CPAP machine. Does it fail to maintain the correct differential pressure, overheat, or become sentient and try to suffocate you?

See Collective Fan Laws. We need to know the current (peak) pressure and just how high the OP is going up.

I mean, if they're on like 15.0 cmH2O and heading up into the scrotosphere somewhere, I'm thinking it will fry.

Call To Posters Who Are One Taco Short of a Combination Plate:

• Put CPAP machine set at 20.0 cmH20 in barrel.
• Hook up Shop-Vac to barrel.
• Seal all leaks with duct tape.
• Crank up everything full blast.
• Continue experiment till everything is engulfed in flames.
• Download info from SD card.
• Rethink what is inherently wrong with this experiment.
• Enjoy ride to the Acorn Farm.

[billbolton]

What happens above 2591 meters?

The S9 ceases to make any further automatic adjustments for altitude and the effective flow rate delivered by the flow generator at any nominated setting will be less than that setting normally indicates. You will therefore need to make manual adjustments to the flow rate setting to achieve the actual flow rate that your require. Its up to you to determine what settings will meet your needs at whatever altitude above 2591 meters that you intend to sleep.

[Sludge]

You will therefore need to make manual adjustments to the flow rate setting to achieve the actual flow rate...

"Pressure"

[Sludge]

Besides, if one is on an "Auto", pressure compensation is academic. If the machine sees events, it will attack them.

Obstructive events, anyway.

And assuming parameters are set correctly.

[popotla]

I posted the original question. Thanks for replying. My plan is to be at heights of up to around 4,000 meters (Andean altiplano) for continual periods of weeks at a time. My S9 has been set on Auto so I'm unable to make adjustments myself.

[-tim]

The S9 was designed in Australia and they can only test up to about 2,280 meters.

If your under 15 cm of pressure, I don't think there is any issue if you use an APAP machine
If you are above 15 cm of pressure, the US navy dive tables could be used for the calculations.

[Overflow]

Had S9 at approximately 2800 metres for 4-5 days. Machine made a lot more noise than usual and didn't seem to be as effective.

[BlowingWithTheWind]

Many years ago, I had a dumb CPAP brick without any altitude compensation. When I went to Denver for a while, it was not blowing at the same rate and I could not sleep- well. That is because, as I remember from my high school physics, pressure decreases with altitude. Thus, the dumb machine that was blowing at a fixed fan speed put out less pressure at altitude. I assume that the S9 algorithms compensate based on pressure. My guess is the machine won't be able to hit the top pressure (20?) above the stated altitude since the fan cannot go any faster. If you are at a lower pressure setting, it will probably work since it will compensate. Of course, this is just a guess and I may be totally wrong!

[BlackSpinner]

I posted the original question. Thanks for replying. My plan is to be at heights of up to around 4,000 meters (Andean altiplano) for continual periods of weeks at a time. My S9 has been set on Auto so I'm unable to make adjustments myself.

Manuals are available online. Adjustments are easy to make. Old fashioned VCRs were more difficult to operate.

Get familiar with your machine - you may need to adjust the lower pressure for the higher altitudes or it will have problem getting up to the pressure you need in time. Assuming you don't have a crappy brick, download sleepyhead software and get used to looking at your data so you can keep aware of what is happening at night. This is a tool to keep you functioning and healthy, and in this situation you need to know exactly how to operate it effectively, no different from using any power tool.

[palerider]

take a manometer if you want to be sure...