silly P&B 420E APAP setting (Initial pressure) question

I guess I (should) know the answer to this already , but I jsut wanted your expert opinions:

On the 420E you can set the Minimum, Initial, and Maximum pressures for APAP mode.
Min and Max I understand.
I also understand that Initial is what it starts out as and if there are no events it drops back down to Min pressure.

Is it also correct that Initial is the pressure that the APAP will jump up to (in a very short amount of time) if it detects an event? And if the event continues then it will climb more slowly after that?

So basically there's a big difference between :
(a) Min=10.5 , Max=16 , Initial=11 and
(b) Min=10.5 , Max=16 , Initial=12 ...?

How does one go about determining what the ideal Initial pressure should be? I'm thinking that it's the pressure which eliminates (most of) the residual events ocurring above the minimum pressure... which may be trial and error and looking at the trends for a few weeks?

As an example, last night I used setting (a) . There were a small jumps but not always quite to 11.0 which is even more strange (e.g. 10.6 or 10.7 from the SL detailed graph, if that's accurate), and then it would go more slowly the rest of the way to 11.0.... but then again I guess it is being smart and if the event is eliminated it doesn't continue all the way to 11. Confusing, or maybe only to me. [SL graph of night (a) - notice around hour 92.5 that the pressure stays just between 10.5 and 11.0 for about 4 minutes, until the next set of events and it increases again.] <= Well this paragraph is more of detour and just thinking out loud. My real question is the previous paragraph.

I guess this qualifies as "tweaking" , i.e. trying to squeeze that last little bit of performance out of the machine

PS.. oh, and thanks in advance Ozij or Snoredog or RG

PPS... Snoredog: I'm still waiting for that good thwacking with the 2x4 regarding the GERD !!!!!!!

From the manual:

They are as follows:
· ramp duration, which can be set from 0 to 30 min in 5-minute increments.
· ramp initial pressure, which can be set between 4 cmH2O and the pressure level in
constant pressure mode or initial pressure in automatically controlled mode.

· The possibility of selecting increments of either 0.5 cmH 2O or up to 1.0 cmH2O. Settings
are always made with the last step selected. So, if the maximum pressure set is 16.5 cmH2O,
and you select a step of 1 cmH2O, pressure values will continue to be expressed in half-
units.

· Initial pressure Pr that can be set between 4 cmH 2O and 20 cmH2O.
· Max pressure (Pmaxi) that can be set between Pr and 20 cmH2O.
· Min pressure (Pmini) that can be set between 4 cmH2O and Pr.

I think Minimum pressure is controlled by Ramp Pressure, Initial pressure is alway the pressure it lands on when machine is powered On, it is what I set as the Minimum pressure compared to other Autos. I use Ramp/Minimum pressure for a lower-than-initial pressure option, enabled when hitting
the Ramp button.

For example:

I may have Ramp set at 6.5 cm and 30 minutes. Minimum pressure will also be at 6.5 cm.
Initial Pressure will be at 8.0 cm and Maximum at 20 cm.

Note: On your 96 hr reports, if your central apnea threshold is 10 cm or under, you need to:

Lower your Initial pressure down to like 7.0 cm,
Set your Command on Apnea (A10) from 10 cm to 9.0 cm,
Any Minimum pressure or Ramp pressure you want can be lower yet.

Your goal (I think) should be to totally eliminate those CA's seen on line 2 of your reports. You don't have any clusters of CA's only the
rouge central on your report.

Thanks SD. I'm talking about the actual Initial pressure setting, not the ramp initial pressure. Or in other words, what the ramp ends up at when it's finished ramping. Found this thread back from Ozij: viewtopic.php?p=259412#259412

She sets her Initial at her titration level, and sets Minimum below that. For me the ideal pressure has been 10.5, and I am reluctant to actually set the Minimum below 10.5. So that leaves me with the question of what should I set initial to?

Maybe the question is more academic given that I don't want to go below 10.5, ever.

On the other hand, you're right I need to eliminate those CA's. If I look back at the historical data, I had the least CAs at 8, 8.5 or 9cm. I had more CA's at 7cm, 10cm, 10.5cm. I've never been able to manage ZERO CA's on average. Even at 7-10 APAP I was still getting some CA's

Then again are we talking statistically significant numbers here? I get between 1 and 4 CA's per night, most I ever had was 7 in one night, once.

The response to flow limitation runs is always less than the response for apneas and hypopneas. Look at the wavy line, just between those 2 flow limitation runs - your breathing was perfect, so the machine stopped responding - but didn't drop back down. For teh second group of flow limitation runs, it bumped up some more. Apnea /CA can happen when you simply turn over - I don't think you should be very concerned with getting rid of all of them.

The machine will respond to apnea and hypopnea below the initial level faster that it will above th initial level. Conversly, it will go down to the initial level faster that it will go down below the intial.

The PB certainly doesn't seem to think you need more than 10.5 - and you can see your flow limitations getting resolved by that exta little jog (thanks to IFL1 being on). Now if it were me, or Rested Gal, or maybe Snoredog - with IF1 on our pressure would be zooming way up, and hoveringt there at the max.

O.

Thanks for the clarification ozij. I think for the time being the settings are OK.

Cheers