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New to CPAP/BiPAP - living at High Altitude
New to CPAP/BiPAP - living at High Altitude
I posted this on another forum but thought I would get opinions here as well. Reading these threads has been incredibly useful as I start this journey. I look forward to getting a BiPAP and using SleepyHead to evaluate my progress.

Sorry for the long first post - a lot of details to cover. I live at 8400' in the Colorado Mountains and will be starting BiPap very soon.

I recently completed a sleep study (at a similar altitude to where I live) and met with a doctor for a follow-up a week ago. I have severe SA and my AHI in the sleep study was 95.9 events per hour, my events consisted of 0.4 central apneas, 17.7 obstructive apneas, 3.6 mixed apneas, 74.2 hyponpneas per hour. About half-way through the study they connected me to a CPAP. The study showed elevated AHI until they had me on a BiLevel at 25/19, then my AHI was 7.4 per hour. I even got 49 minutes of REM sleep during the CPAP/BiPap part of the study and felt great the next day - I was a "lucky" one that slept great during the study. I will be using additional O2 at night - the sleep study recommended 4L so we will start there. I recently recovered from severe pneumonia requiring surgery so my O2 requirements might change as my lungs continue to heal.

The doctor first prescribed me a Respironics System 1 BiPAP Pro with Bi-Flex with datacard, heated humidity and pressure set at 25/19. Based upon reading this forum I convinced them to change my order to an Auto machine, which they have done (So now it will be a BiPAP Auto). My concern is this machine and all Phillips machines say max altitude 7500 feet (in their manual). When I met with the doctor I told him my only close DME is Lincare (others would be in Denver an hour+ away) and they told me the previous week they "only" provide ResMed devices and he said he prefers Respironics and that is what the order will specify. I mentioned what I had seen about the altitude issue - ResMed rates to 8500' and Respironics rates to 7500' and he said he would look into it. I asked the doctors office about getting a copy of the order and when I saw it is the Respironics, I emailed back the office about the altitude issue she said the machine will self-adjust (which it will but only up to 7500 feet).

So I am wondering how big of an issue this is and how far to take it, and how to do so. I talked to Lincare about the altitude issue and the person in the local office will submit the paperwork to the "Lincare Bipap person" and state the machine needs to be rated for 8500' and then once they specify the machine she will contact the doctor if it doesn't match his specific request for a Respironics. She said they deal with this frequently. I figure I will let Lincare fight back some and be the "bad cop" now instead of me being a pain to the doctor and challenging him more (unless that is what is needed).

Thanks for all the advice you have provided while I lurked here and learned enough to insist on an Auto Machine.
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RE: New to CPAP/BiPAP - living at High Altitude
Sounds like you have done your homework. The Auto Bilevel should give you some periods of relaxed pressure from the high pressure you require.
In the ResMed machines, I believe only the Auto Bilevel will run above 20 (up to 25) -- at least that was the case with the S9 series.

I'm not sure if the 7500 feet rating will be an issue. Often these ratings have a built in margin. i.e: It may perform to 9000 feet; but they will only certify it to 7500 feet. Both the ResMed and Respironics machines are good machines. In your living situation the 8500' rating may be the deciding factor.

I have designed many electronic systems for unmanned space operation; and if the environment is predicted or specified as X, the design would be for 2X or even 3X. I doubt there's that much design margin in the operational altitude of an xPAP -- but there is some.

In summary: You have raised all the right issues with your doctor and the DME.

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RE: New to CPAP/BiPAP - living at High Altitude
Hi forJO,
WELCOME! to the forum.!
It's great to hear that you are pro-active with your CPAP therapy.
Much success to you in getting the machine you really want.
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RE: New to CPAP/BiPAP - living at High Altitude
The way the auto bilevel adjusts to your needs is not affected much by altitude. It will increase EPAP and pressure support according to its programmed algorithm and work just fine. Technically without altitude compensation a blower will produce The amount of pressure generated by the CPAP fan decreases with altitude due to lower gas density. The specification for the PRS1 indicate it is able to compensate up to 7500 feet, but keep in mind in an auto machine, the pressure and flow is variable based on sensed respiratory events like flow limitations, snores and volumetric changes. I have used mine at similar high altitudes for skiing trips and visiting my parents cabin in Allens Park. This is probably one of those "don't worry about it" moments. Even if the sensed pressure is off by a small amount, the machine continues to respond to events according to its program.
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RE: New to CPAP/BiPAP - living at High Altitude
I agree - while it may not be accurate above the 7500 ft, it is still 100% effective. For auto- machines, the pressure will increase based on the events you experience, until it can splint your airway.

Dedicated to QALity sleep.
You'll note I am listed as an Advisory Member. I am honored to be listed as such. See the fine print - Advisory Members as a group provide advice and suggestions to Apnea Board administrators and staff concerning Apnea Board operation and administrative policies. Membership in the Advisory Member group should not be understood as in any way implying medical expertise or qualification for advising Sleep Apnea patients concerning their treatment.
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RE: New to CPAP/BiPAP - living at High Altitude
If we use at 8500 ft elevation a machine which can compensate for only up to 7500 ft elevation, I think the effect on therapy would be that when set to 25 cm H2O pressure the machine might be producing around 24.5 instead of 25. In other words, I think the difference would be small.

In effect, I think the top pressure which the machine would be able to reach would be 24.5 or so, instead of 25.

If using an Auto machine at 8500 ft elevation, I think the effect on therapy of having a machine which autoadjusts for elevation only up to 7500 ft versus up to 8500 ft would be completely negligible as long as there would be room for the machine to increase the pressure in response to obstructive events.

If using a Philips Respironics BiPAP Auto machine, a prescription of 25/19 could be (and in my view, should be) revised to give the machine some working room. For example: Min EPAP 15, Min PS 5, Max PS 7, Max Pressure 25. (Only extremely expensive types of bilevel machines can go higher than 25.)

If using the ResMed A10 VAuto, PS (Pressure Support) cannot self-adjust and would be a fixed number such as 6. (I think it is a helpful feature of the PR BiPAP Auto that it can very slowly automatically self-adjust PS, using only as much PS as needed to avoid Flow Limitation.)

If the titrated pressures of 25/19 were determined while you were sleeping in the supine position, and if at home you are able to always sleep on your side and never on your back, then I think it is quite likely that you won't need the pressure to go as high as 25, and you might spend the majority of the night with an EPAP closer to 15 and an IPAP closer to 21, allowing your machine room to raise the pressure when needed to respond to obstructive events, and it won't matter that because of the high elevation the machine thinks it is using an EPAP of 17 when the machine is actually using an EPAP of 16.5 or so.

Another possibility is if, because of excessive air swallowing or excessive leaking or for some other reason, you find that you cannot tolerate a Max Pressure of 25 and need to use less pressure; in that case it would not matter at all that the machine has slightly reduced capability in how high its pressure can go.

Membership in the Advisory Member group should not be understood as in any way implying medical expertise or qualification for advising Sleep Apnea patients concerning their treatment. The Advisory Member group provides advice and suggestions to Apnea Board administrators and staff on matters concerning Apnea Board operation and administrative policies - not on matters concerning treatment for Sleep Apnea. I think it is now too late to change the name of the group but I think Voting Member group would perhaps have been a more descriptive name for the group.
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