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Min/Max PS Settings - Help please!
#11
(08-21-2014, 12:36 PM)retired_guy Wrote: What is the breakdown of your ahi? OA's vs CA's, etc. It does appear you got good results by dropping the range a little, which could be explained by reducing leakage as much as anything, so what is your leakage doing, and what is your average pressure doing?

Personally I like a tighter range such as your 13/17 versus the 13/25. In the end what that range really should be will be a result of sliding the bottom up, the top down, or any number of things to get your ahi to the sweet spot.

And, anytime you change anything you should run for a few days before you get too excited about the results.

Mongo and retired_guy: Thank you for the posting instructions and for asking for more detailed results info. We are on the road (with my machine!) bringing my daughter to college. I will post Sleepyhead graphs on Monday when we're home and I will be back at my computer.
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#12
(08-21-2014, 04:53 PM)petemsw Wrote: The prescription that came from my sleep study's CPAP/BiPAP test night was EPAP=8, IPAP=13 using fixed settings.

That's a PS of 5.

Quote:When that setting only got me from a pre-PAP AHI of 85 to the 35-40 range, my sleep doc and his tech put my machine into Auto BiPap mode with the MinEPAP of 13 and MaxIPAP of 25, the highest setting on my machine.

And a PS of zero. Did you notice that the pressure was higher during exhale? It should have been noticeably less comfortable.

When your AHI was in the 35-40 range was it composed mostly of obstructive apneas and hypopneas, or were there a large number of centrals?

I really don't know why they made the changes they did, and I recommend you call them and ask them why they lowered your PS from 5 to zero.

It's possible that lowering the PS was done in attempt to reduce the number of centrals, and that changing the IPAP from a fixed 13 to a 13-25 range was done in an attempt to reduce the number of obstructive apneas and hypopneas.
Sleepster
Apnea Board Moderator
www.ApneaBoard.com


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#13
(08-21-2014, 08:04 PM)Sleepster Wrote:
(08-21-2014, 04:53 PM)petemsw Wrote: The prescription that came from my sleep study's CPAP/BiPAP test night was EPAP=8, IPAP=13 using fixed settings.

That's a PS of 5.

Quote:When that setting only got me from a pre-PAP AHI of 85 to the 35-40 range, my sleep doc and his tech put my machine into Auto BiPap mode with the MinEPAP of 13 and MaxIPAP of 25, the highest setting on my machine.

And a PS of zero. Did you notice that the pressure was higher during exhale? It should have been noticeably less comfortable.

When your AHI was in the 35-40 range was it composed mostly of obstructive apneas and hypopneas, or were there a large number of centrals?

I really don't know why they made the changes they did, and I recommend you call them and ask them why they lowered your PS from 5 to zero.

It's possible that lowering the PS was done in attempt to reduce the number of centrals, and that changing the IPAP from a fixed 13 to a 13-25 range was done in an attempt to reduce the number of obstructive apneas and hypopneas.
Sleepster, I'm afraid you're giving them way too much credit for actually thinking. After my initial sleep study, the doc pointed out the high number of obstructive apneas and hypopneas I had experienced without CPAP. No mention was made of centrals, and my copy of the report has no mention of them either. When I saw the doctor at my request 10 days later because my AHI was not going below 35, all he said to me was "you're right, your AHI is still too high." All he looked at was the readout on the machine, he did not print a report from the memory card. He seemed at a loss for what to do as he left the room for 15 seconds, returning with the practice's daytime tech in tow. The tech changed the settings and told me he what he was doing: putting the machine in auto mode, setting the Min EPAP to my former fixed IPAP pressure (13), and "letting the machine determine how much pressure you need to clear your airway" by setting the Max IPAP to 25. I noticed he had left the PS settings alone where they were, both at 0, I asked him if that was OK, and he told me they were irrelevant because he set the min and max pressures in auto mode. It was educated guesswork, and you have now cleared up the issue by helping me understand that when PS min/max=0, the machine is essentially operating in Auto CPAP mode.

So back to the present and the question of where to set those PS controls for now, and any changes to the Min EPAP and Max IPAP settings to accommodate the swing and the exhalation relief interval. I'm interested in what you would do if you had been prescribed a max IPAP pressure of 17 and wanted to translate that to Auto BiPAP mode with MinEPAP, MinPS and MaxPS settings. I take full responsibility for the settings on my machine and will have them approved by my sleep doctor, I'm just seeking your non-medical opinion on roughly what settings someone with a MaxIPAP RX of 17 might be given by a sleep doc for MinEPAP, MinPS and MaxPS. Thank you for your help with this.
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#14
(08-21-2014, 08:39 PM)petemsw Wrote: After my initial sleep study, the doc pointed out the high number of obstructive apneas and hypopneas I had experienced without CPAP. No mention was made of centrals, and my copy of the report has no mention of them either.

Therefore the centrals you are experiencing now are called CPAP-induced centrals and usually they subside as you adapt to CPAP therapy. BiPAPs can also induce central apneas.

Quote:So back to the present and the question of where to set those PS controls for now, and any changes to the Min EPAP and Max IPAP settings to accommodate the swing and the exhalation relief interval.

Given that we can't trust your doctor's actions, I have to wonder how it was originally determined that 13/8 was the right pressure for you, that you needed a BiPAP instead of a CPAP, and why they gave you an auto BiPAP.

Don't get me wrong, I think that everyone with simple obstructive sleep apnea should get at a minimum an auto bi-level machine like yours.

Since originally your PS was set at 5, I'd start there. Set the minPS at 3 and the maxPS at 5. Set the minEPAP at 8 and the max IPAP at something like 17.

There is also a Bi-Flex setting. I believe the default setting is 2 so I'd just leave it there for now.

It's important that we get at least a week's worth of data to see how your body and mind are responding to the settings.

When they switched me from CPAP at 13 to BiPAP at 13/8 my central apnea index shot way up. They lowered the pressure to 11/8 then 10/7. After that I took over and started tweaking things myself.

It takes time for your body to adapt, but once it does it's likely those centrals will go away. I can now go up to a pressure of 13.6/9.4 with no problems, but if it stayed there all the time I'd swallow a lot of air. It's rare that I need a pressure higher than 11.0/6.8.

These are all things that I had to determine by trial. Looking at the data and monitoring the leak rate is necessary for me.
Sleepster
Apnea Board Moderator
www.ApneaBoard.com


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#15
Thank you, Sleepster. I'm so grateful to you for taking the time to make these excellent suggestions and for explaining things to me!
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#16
I was told 13/8 was the point at which my obstructive apnea and hypopnea incidents became minimized during the CPAP trial overnight session. The tech on duty at the time told me they usually switch to BiPAP when the needed pressure reaches 15, but she happily complied with my request to switch sooner so I'd get approved for a BiPAP.

I will sleep for 7 nights at the revised settings, then I'll post my data and ask for further comments. These suggested settings give me a great starting point, the first truly useful set of pressure levels and pressure support since starting therapy last month. Huge thanks again.
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#17
(08-22-2014, 07:54 AM)Sleepster Wrote:
(08-21-2014, 08:39 PM)petemsw Wrote: After my initial sleep study, the doc pointed out the high number of obstructive apneas and hypopneas I had experienced without CPAP. No mention was made of centrals, and my copy of the report has no mention of them either.

Therefore the centrals you are experiencing now are called CPAP-induced centrals and usually they subside as you adapt to CPAP therapy. BiPAPs can also induce central apneas.

Quote:So back to the present and the question of where to set those PS controls for now, and any changes to the Min EPAP and Max IPAP settings to accommodate the swing and the exhalation relief interval.
...
Since originally your PS was set at 5, I'd start there. Set the minPS at 3 and the maxPS at 5. Set the minEPAP at 8 and the max IPAP at something like 17.

There is also a Bi-Flex setting. I believe the default setting is 2 so I'd just leave it there for now.

It's important that we get at least a week's worth of data to see how your body and mind are responding to the settings.

(08-22-2014, 10:25 AM)petemsw Wrote: I will sleep for 7 nights at the revised settings, then I'll post my data and ask for further comments.

Hi petemsw,

You reported that your machine sometimes needed to raise the pressure above 17. This would have been done to avoid/stop obstructive events.

Obstructive Sleep Apnea is usually highly dependent on sleep position. Usually, the worst sleep position is the supine position (flat on our back). If you can ensure that you will never be sleeping on your back, you might find that your pressure never needs to go as high as 17.

I wear a snug teeshirt with a tennis ball in a pocket sewn high on my back, between the shoulder blades or a little higher, to ensure that when I roll onto my back while sleeping I will wake enough to keep rolling until I am laying on my other side.

By the way, if many of your apneas were Centrals, or if many of your hypopneas were Periodic Breathing (which also are Central in origin), then it would make perfect sense that your doctor would try reducing the Pressure Support to zero, effectively setting up your machine to operate like an APAP machine.

As Sleepster noted, bi-level therapy (which is whenever PS is non-zero) is known to sometimes cause central events (in some patients).

So keep an eye on how many Central Apneas and Periodic Breathing events occur, and realize that reducing PS may help to reduce these central events.

If the number of Centrals is far less than 5 per hour, and if the events are shorter than 30 seconds or so, these centrals would be deemed not a problem. For example, usually insurance companies will not cover a machine to treat Centrals unless the number of Central Apneas per hour (CAI) is both greater than the number of the Obstructive Apneas per hour (OAI), AND the CAI itself is greater than 5 per hour, AND the AHI is at least 5 or 10 or 15 (depending on insurance company), AND a special ASV or ST titration has been pre-authorized and performed and shows that the ASV or ST machine is adequately treating the condition.

Take care,
--- Vaughn
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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