(01-28-2014, 05:01 AM)vsheline Wrote:
(01-27-2014, 06:38 PM)Kate Wrote: I'm not sure about what is involved in setting my machine, but the doctor had wanted the pressure set at 8/4. I believe that's inhalation 8, inhallation 4.
Your profile says your (old) pressure was 9. This would seem to indicate your pressure when exhaling needed to be 9 or a little lower (if you were using EPR) to prevent obstructve apneas.
When titrating straight CPAP, it is typical that the OAs are the first events eliminated (they turn into hypopneas) and that it requires more (inhalation) pressure to properly prevent the residual hypopneas--i.e. the "OAs turned into Hs". On a straight CPAP titration, they keep increasing the pressure until these residual Hs are eliminated. On a bi-level titration the EPAP is increased for OAs, but not Hs; the IPAP is usually increased for both OAs and Hs. So once the OAs are eliminated, the EPAP is not increased further, but they continue to increase the IPAP until the residual Hs disappear.
As a result, for people being switched from straight CPAP to bi-level, it is not uncommon for the EPAP pressure to be several cm lower than the old straight CPAP pressure and the IPAP pressure to be roughly the same as the old CPAP pressure.
Quote:With the change to bilevel, it is possible your doctor is prescribing EPAP = 8 (to continue to prevent obstructive events) and Pressure Support (PS) = 4. This would make your inhale pressure 12. I think these would be reasonable settings for someone who needed a pressure of 9 when on standard CPAP machine. You can ask your doctor if that was his intention.
Without knowing more about how the script is actually written I would NOT make this assumption. It could be that the OP has some problems with pressure induced centrals (otherwise why the switch to an ASV machine?) and hence the doc wants to see if reducing the overall pressure needs is enough to fix the pressure induced centrals. It is quite possible that an IPAP = 8 or 9 is enough to take care of the Hs, and the reasoning would then be that less pressure is needed to take care of the OAs.
Quote:When treating central events an ASV machine somtimes needs to automatically increase Pressure Support as high as 10 or even higher, to keep you breathing. I reccomend setting the supper limit for Pressure Support at 10 or higher. The PS won't go higher than necessary.
The exact meaning of the PS setting on a VPAP ASV machine depends on the mode that you are using the machine in. If you're not using it in ASV mode, then there will only be one PS setting and it will fix the distance between EPAP and IPAP. In other words, if the machine is not in ASV mode, setting (min) EPAP = 8 and PS = 10 will result in a starting IPAP = (min) EPAP + PS = 8 + 10.
In ASV mode, however, there are two
PS settings. The min PS setting is what controls the relationship between IPAP and EPAP when the machine is not trying to trigger breaths. At the start of the night, IPAP = EPAP + min PS. When the machine needs to trigger an inhalation, the IPAP is increased (sometimes dramatically) while the EPAP is left alone. The maximum the IPAP can increase to, however, is controlled by the max PS setting: max IPAP = EPAP + max PS.
To the OP: You need to clarify with your doctor exactly how s/he wants your machine set up. These are the questions you need to get answers to in writing
What mode to use? Regular VPAP S, VPAP ST, or VPAP ASV?
Min EPAP = What?
Min PS = What?
Max PS = What?
Max IPAP = What?
On the S9 VPAPs there are also settings that control how and when the machine changes from IPAP to EPAP and back. So you will need to know what the doc wants you to use for:
TI max = What?
TI min = What?
Trigger sensitivity = What?
Note that in some modes, you might not have all these settings. In other modes, you will have more settings that you need to have the doc's written instructions in order to get the machine set up correctly. In both ST an ASV mode, there will be settings to control when the machine starts to trigger inhalations (the "breaths per minutes rate" and the "target minute ventilation" settings).