Need some help on settings please

[izzyb]

snoredog, I am so lost. Are you saying that I shouldn't use the auto? I figured it was better than fixed if it could automatically give you the pressure you need each time, and wondered why they don't put everyone on it. I don't get it.

So, the first night I put it on auto and set my pressures to 18/10, PS4 and my results were 16.5/14 with a great leak rate and a great AHI, does that mean my fixed pressure should be 16.5/14?

[Fafner]

Izzyb,

Is that a beagle face by any chance on your picture icon? It sure looks like a face that I have often awakened to if I oversleep.

fafner

[ozij]

snoredog, I am so lost. Are you saying that I shouldn't use the auto? I figured it was better than fixed if it could automatically give you the pressure you need each time, and wondered why they don't put everyone on it. I don't get it.

So, the first night I put it on auto and set my pressures to 18/10, PS4 and my results were 16.5/14 with a great leak rate and a great AHI, does that mean my fixed pressure should be 16.5/14?

Bump

[-SWS]

FACT: with your
IPAP Max=18 cm
EPAP Min=10 cm
PS=RG's 8

With those settings, you will NEVER EVER see more than 6 cm Pressure Support. Like I said she recommends that for everyone no matter what their condition may be.

Now what I explained above works in the opposite directions also, as events subside EPAP will drop as it drops IPAP will remain high, when EPAP and IPAP separation reaches 4 cm from my tether it will begin pulling IPAP pressure down. With a PS=8? My settings will also bring your pressure down faster than the invalid for your pressure settings of PS=8.

SO I would ask RG how her PS=8 Pressure Support setting will ever be used when there is only 6 cm of Pressure Support travel possible within that 18/10 pressure range you are using.

Let's use the above 10cm EPAP and 18cm IPAP settings to answer your question that I have underlined:

Setting Max PS at 8- With a max PS of 8, the above settings can travel as wide apart as IPAP=18 & EPAP=10 (note that's a full 8cm EPAP/IPAP PS spread, despite a 6cm variance or range-of-travel---and that 6cm limit on variance (but not max PS) is simply because PS will never drop below the 2cm lower limit imposed by machine design)

Setting Max PS at 6- With a max PS of 6, the above settings can only travel as wide apart as IPAP=16 & EPAP=10... or say IPAP=17 & EPAP=11... or perhaps IPAP=18 & EPAP=12 (note that's a maximum EPAP/IPAP spread or PS of only 6cm, but these settings are also bound by that same 2cm lower limit imposed on PS)

Snoredog, your question to Rested Gal seems to confuse the separate issues of EPAP/IPAP variance (range of travel) with max PS. Her suggested setting does, indeed, allow for a max PS of 8cm to be achieved. I agree that there can be separate physiologic reasons for wanting to restrict max PS. But your question to Rested Gal implies that a 6cm range-of-travel somehow means a max PS of 8cm cannot be achieved.

Summary:
PS lower limit is hard-coded at 2cm
PS upper limit is manually entered as max PS (8cm here)
PS variance in this case is 6cm (determined by both the upper and lower limits of PS)
The hard-coded 2cm lower limit of PS does not restrict the upper limit of PS:
PS can thus travel to the full value of 8cm in this example
PS can travel no lower than 2cm

[Snoredog]

-SWS you left off the part where EPAP will never increase using those settings for Hypopnea, IPAP will simply run up to the max trying to kill hypopnea with no help what so ever seen from EPAP, all that does is result in a much higher PS than what may be optimally needed. By contrast If Hypopnea was the event seen and PS=4 as IPAP reached 4 cm delta from EPAP it would begin pulling up EPAP which only eliminates the Hypopnea sooner than allowing the IPAP to run to the Maximum pressure.

Using the settings you quoted above,

EPAP=10
IPAP Max=18

When she turns on the machine:

EPAP will land at 10 cm
IPAP working pressure will land at 12 cm or 2 cm higher as 2 cm of Pressure Support is built-in.

There is only 6 cm possible travel between 12 and 18. Since max PS=8 or so wide EPAP will never assist IPAP pressure in eliminating the Hypopnea due to the range set.

EPAP only increases independently in the presence of apnea and snore. If a shorter Max PS setting was used it could also assist
in elimination of Hypopnea or the events driving up IPAP.

But it does no good to explain it, she won't understand it anyway.

[-SWS]

Well, Snoredog, my above post was only intended to answer your rhetorical question (that I have underlined above) claiming that PS can never reach 8cm with those settings.

By contrast If Hypopnea was the event seen and PS=4 as IPAP reached 4 cm delta from EPAP it would begin pulling up EPAP which only eliminates the Hypopnea sooner than allowing the IPAP to run to the Maximum pressure.

Well, here you're saying that by decreasing max PS to 4cm, EPAP is going to being forced higher with that 4cm tether. I agree that EPAP will be forced higher. And I also agree that situation should work out better for many patients for a few reasons having to do with the timing and mechanics of airway collapse. However, those time-based mechanics aren't universal. Otherwise Respironic simply would have limited max PS to 4cm.

Rather what you have described should work very well for many patients. Who knows.. possibly most patients. However, for some patients there are a variety of advantages to higher PS values. Obese apnea patients tend to be better candidates for higher PS, because work of breathing (WOB) is decreased. Apnea patients with airway inflammation or COPD tendencies can sometimes fare better with higher PS values.

Full apneic occlusions tend to occur at the end of expiration. And that is why Respironics raises EPAP in response to apneas. Partial sagging or hypopneic closure tends to occur during inspiration. And that is why Respironics raises IPAP instead when hypopneas are detected. But pulling EPAP up as IPAP addresses events during inspiration can be unnecessary for some patients who fare well by treating hypopneas with IPAP increases as Respironics intends.

I really think a wide PS range is going to be a blessing for only some patients and a true show-stopper for yet other patients. Respironics happens to default that max PS setting to a value of 8cm. I also think the Encore graphs and especially how a patient feels/sleeps with either of those max PS strategies will aid in that same kind of trial-and-error phase that ordinary APAP users often must incur. I honestly think they're both darn good PS strategies serving different sets of circumstances.

[izzyb]

But it does no good to explain it, she won't understand it anyway.

Snoredog, is that aimed at me? I'll wait for your reply before I get testy.