(07-26-2014, 10:50 PM)wnorm Wrote:
(07-26-2014, 08:12 PM)robysue Wrote: Rather than increasing the max IPAP from 16 to 17, you may be better off either increasing the min EPAP OR increasing the min pressure support so that your beginning IPAP pressure is (much) closer to what you actually need for controlling your obstructive sleep apneas.
Thank-you for your response. My settings on the Resmed S9 were min 4, max 16, EPR 3, ramp 0,
As robysue suggests, it is usually best to only make one change at a time, gathering data (preferably for a couple weeks) between changes.
My suggestion would be to increase the Minimum EPAP setting first. I would suggest jumping it to 6, and, if that helped, later trying 7.
EPR in ResMed machines is a form of simple bi-level therapy (Pressure Support). Since EPR was 3, I would consider raising the Min Pressure Support to 1 or 2 or 3. (Later, after seeing how things are with a higher Min EPAP.) But keep in mind that raising Min PS may tend to reduce obstructive events at the expense of raising central events. If that turns out to be the case for you, I would suggest finding a happy compromise in the Min EPAP, Min PS and Max PS settings which minimizes the overall AHI but also takes into account (minimizes) how often long duration events are occurring, such as obstructive apneas lasting longer than 30 or 40 seconds, as shown in SleepyHead reports.
Raising Min EPAP would tend to reduce obstructive apneas and hypopneas, especially at the beginning of the night, before the BiPAP Auto has had time to slowly adjust itself to our pressure needs, or whenever we enter REM stage sleep or roll onto our back and our pressure needs increase.
Raising Min PS would likely feel more comfortable (since you have been used to EPR of 3) and would tend to reduce RERA (Respiration Effort Related Arrousal) events but may also increase central events. By the way, although some patients assume central apneas are somehow worse than obstructive apneas, in my opinion short central events are no more harmful/stressful (and perhaps are less harmful/stressful) than short obstructive events, so, in my opinion it is good to aim to lower the overall AHI without regard to how many are central versus obstructive.
Some general background info:
I think it is a common mistake that the bottom end of the pressure range is left at 4 cm H2O too long. Starting so low can often be helpful for first few days or weeks of CPAP therapy, until our chest muscles gain strength and we become accustomed to breathing against pressure, but I think many patients very quickly find it more comfortable and therapy is improved by having a higher starting pressure, such as 6 or higher. (A few PAPers prefer the minimum pressure to be close to their 90% or 95% pressure.)
In your case, the PRS1 auto-adjusting machines (including the BiPAP Auto) are much less aggressive (swift) in raising the EPAP pressure than ResMed auto-adjusting machines are. So every time we roll onto our back or enter REM stage sleep and our pressure needs increase, the ResMed machine would have responded more quickly.
But, on the other hand, the ResMed auto-adjusting machines treat the minimum pressure setting as a target which they are always slowly trying to return to, which the PRS1 models don't do. PRS1 tend to stay put once the pressure is high enough to adequately prevent obstructive events, but, again, PRS1 machines do not adjust as quickly when our pressure needs suddenly increase.
If feasible, to monitor how low your blood oxygen is dipping throughout the night, I suggest buying a recording wrist-mounted pulse Oximeter, such as are sold by Supplier 19. (Link to Supplier List is at top of all forum pages.)