(12-15-2013 01:52 PM)pdeli Wrote: When I first put the mask on at night the machine says 6 IPAP, 6 EPAP.

This indicates that

min PS = 0. More on this in a bit.

Quote:My reference to “sensitivity” was not in terms of anything I can actually feel or am consciously aware of, but rather a hypothesis that whatever the settings are, they don’t seem to actually activate the pressures to change very soon. If I wake up in the middle of the night, I can sometimes see a higher IPAP than 6, and that number will stay up for a while as long as I feel like staying awake to watch it. But staying awake of course not what I’m trying to accomplish here.

If there are no events (OAs, Hs, RERAs, snoring or FL) during the first 18-20 minutes after you first turn the machine on, the Auto algorithm is not going to increase either the IPAP or the EPAP. About 18-20 minutes after the machine is turned on, the Auto algorithm should do its first test pressure increase in the IPAP as part of the proactive "search" routine. Over the course of about 4 minutes, the machine will increase the IPAP pressure by 2cm (at a linear rate of 0.5 cm/minute) while it studies the shape of the inhalation parts of the wave flow data. If no improvement is found during the test pressure increase, the machine will lower the IPAP pressure back down to its original setting over a one minute period. If there's nothing in terms of OAs, Hs, RERAs, snoring, or FL that is being detected, the "search" algorithm will typically kick in about every 10 minutes or so. Here's an example of what those test pressure increases look like when there's no improvement found:

Each of those bumps in my IPAP graph is one cycle of the "search" algorithm. If the peaks in your IPAP graph look like these, all it means is that the machine is managing your OSA very well and there's nothing the machine can find in the wave flow that justifies increasing the pressure.

When improvements are found, the IPAP pressure continues to increase at a rate of about 0.5 cm/minute until the machine can detect no further improvements. In the next shot, we see my pressure curve for the whole night:

all the green ovals are around "test pressure increases" that resulted in no improvement in the wave flow; the purple ones are around test pressure increases that did show improvement. The uncircled increases in IPAP or EPAP are due to other things like FL, snoring, OAs, RERAs or Hs.

Quote:One thing that is still not clear to me is the min PS concept. Is that the difference in my case of 16-6, or 10?

For any individual breath,

PS = IPAP - EPAP The

min PS setting determines how close IPAP and EPAP are allowed to get to each other. In your case it appears

min PS = 0 since you report that at the beginning of the night both IPAP and EPAP = 6 =

min EPAP.

The

max PS setting determines the largest difference that is allowed between IPAP and EPAP. In other words, the

max PS setting sets up the following inequalities:

On any given breath: EPAP +

min PS <= IPAP <= EPAP +

max PS.

Let's look at how different

min PS and

max PS settings will affect your pressures, given that

min EPAP = 6 and

max IPAP = 16.

If

min PS = 0 and

max PS = 8, then your pressures will always be in the following ranges:

IPAP: 6 <= IPAP <=16 since

min IPAP = min EPAP + min PS
EPAP: 6 <= EPAP <= 16 since

max EPAP = max IPAP - min PS.

And if EPAP = 7 at a given point in the night, the corresponding IPAP must satisfy: 7 <= IPAP <= 15 since 7 = EPAP + min PS and 15 = EPAP + max PS.

But if we set

min PS = 2 and

max PS = 8, then your pressures will always be in the following ranges:

IPAP: 8 <= IPAP <=16 since

min IPAP = min EPAP + min PS
EPAP: 6 <= EPAP <= 14 since

max EPAP = max IPAP - min PS.

And if EPAP = 7 at a given point in the night, the corresponding IPAP must satisfy: 9 <= IPAP <= 15 since 7 = EPAP + min PS and 15 = EPAP + max PS.

Since you say:

Quote:My C-Pap settings were 7.

You might be more comfortable setting

min PS = 1 which would mean that your starting IPAP = 7 = your old CPAP setting.