What is the basic reason for restricting your pressure range

I'm trying to understand the advantage to restricting your machine's pressure range? Not saying it's a bad thing, I'm just trying to learn. But if the machine is an auto, won't it only ramp up if it needs to clear an event? If it can't ramp up high enough, isn't that a bad thing?

For instance I've got my machine set to run from 10-15 right now. And it seems to spend at least 10% at each setting throughout the night. So I'm just not sure which direction I should be tightening up the settings.

Mine is also set 10-15.

When I first got it, it was set 6-15.

When I changed the lower to 10, the maximum upper dropped from 14+ down to around 12 most nights.

I don't see a problem with having the higher limit higher but I think having the lower limit as close as posible to your minimum required pressure overnight works better.

So I looked at my resscan data and saw that the machine rarely went below 10 so that is the number I chose as the lower limit.

I think the machine " hunts" less if the lower pressure is correct and it seems to react better - very scientific isn't it!

I was going to ask this exact same question.

So, I would think you have to be able to get your data to determine that lower number?

I seem to be doing well on a wide range set from 4 - 16 on an M Series Aflex. AHI of 1.5 for the week, with an average pressure of 13 from the little I can see from the screens. I have a card reader on the way...and software so I can see the data in a lot more depth. Been on CPAP for just 5 weeks.

Other hints on establishing this range?

TIA

tighter the range ... faster the response time to an event...

just my .02

wolf

The lower number is set as a starting pressure; if you know that you will need at least 10 cmh2o it is sort of silly to start at 4 cmh2o, set it at maybe 9 or 9.5.

The higher number is set to prevent runaway. Auto PAPs can and do run away, they ramp up up too high and could start inducing centrals.

Many people find that they do better with the range set very tight: I do better with a single pressure CPAP.

So if I'm spending 10% of my night at 10, and 10% at 11, does that mean I shouldn't raise the lower setting?

I found by raising the lower pressure I had less HI which meant less OA's.

I had a trial on an auto last fall, before I bought my own. My 90% pressure was 11cm. That means that I spent 90% of my night at 11cm or less. I spent 10% at other pressures between 11cm and 14 cm. The auto was set from 9 cm to 14 cm for me in that trial but my numbers were high - too many apneas and hypoapneas.
I shared my numbers with some people on this forum and I got the suggestion that I should set my lower pressure at or close to my 90%. That being 11cm, I set my low at 10.5cm. I was being "yoyoed" as the mentor described too much with my upper pressure at 14cm. She suggested I set my upper at 13cm to start. With that, I set my machine at 10.5cm to 13cm. There were other suggestions I could try if that didn't help but I have stayed at that range since I am doing so well. I rarely have an AHI above 2. I sleep well and am less fatigued during the day. With that tighter range my machine responds faster to events and doesn't go too high and cause events.
In the light of my experience, you might find a similar range using your 90%, to be more helpful.
As I look again at your nightly numbers for June 17, I wonder though if going to a minimum of 12.5cm , in your case might be too big a jump all at once. All that vibratory snore activity took place at 15 cm. You said that was a one night thing though so I'm not sure about your upper setting. As far as your lower setting goes, you might try upping it to 11 though and leaving your upper at 15 for another while. Actually, you might try basing your lower pressure on your sleep study titrated pressure, since you did not have an auto trial as I did (I don't I remember you saying that anyway). You might set your lower at 1 or a 1/2 cm below it and see if a lot goes on at the upper pressure (that would be not changing your upper from 15 right now). If a lot of apneas, etc happen at the higher pressures you could then lower that high setting.
Others here tonight have suggested upping your lower pressure. I would agree. It's deciding how much to raise it. They have also suggested narow ranges. That has had great results for me.
AGAIN, I am no expert and do not have a lot of experience but am sharing what experience I have! It is best to only change one thing at a time anyway and try it for a week.

silver123 wrote:I was going to ask this exact same question.

So, I would think you have to be able to get your data to determine that lower number?

I seem to be doing well on a wide range set from 4 - 16 on an M Series Aflex. AHI of 1.5 for the week, with an average pressure of 13 from the little I can see from the screens. I have a card reader on the way...and software so I can see the data in a lot more depth. Been on CPAP for just 5 weeks.

Other hints on establishing this range?

TIA

You have the correct idea, getting the software and reader is a good idea, reading from the screen can be misleading. To be any good at all it has to be zeroed (reset) daily, even then you can't see the full picture of why things happen. Jim

Snoring and leaks can drive the APAP to the top of any set range that's why we limit them.

my guess:

because your SDB events seem to follow a sine wave or bell curve, the object is to get your pressure set where the fewest events are seen at the lowest point of the bell curve and then always on the down stroke vs up stroke.

This can clearly be seen on the AHI vs Pressure report that Derek and James Skinner developed for EncorePro. If you don't stop with pressure increases and start on the up stroke your SDB events may get much worse before they ever get better. If you apply 2-3 pressure increases and things don't settle down, you have either not gone far enough or have gone too far.

If you have reports and over titration is encountered, patterns may imerge showing increase in frequency of events such as clusters of apnea, these will clearly look different than your normal patterns of SDB.

Sometimes flow limitation and snoring events adversely drive up the pressure on the autopap, this can lead to unstable breathing where more SDB events are seen.

Then I rely on my old common sense, if it don't work one way try the other

Well, I think I will tweak it a little tonight. I thought I had it set at 10-15, but it was actually 10-14.5. Which seems odd that my 90% pressure is 14.2 for the week.

Anyway, I think I will try 12-15 and set the ramp pressure at 10.

Well, that didn't go well. For starters, it took me forever to go to sleep. And then I slept poorly and woke up several times. I don't know if that was the CPAP settings or just me. But when I did sleep my AHI was 7.2 (it has been in the low 3's). I guess I'll keep the settings where they are for a few more days. It seems odd that just that small change made that much difference.

Billmanweh wrote:Well, that didn't go well. For starters, it took me forever to go to sleep. And then I slept poorly and woke up several times. I don't know if that was the CPAP settings or just me. But when I did sleep my AHI was 7.2 (it has been in the low 3's). I guess I'll keep the settings where they are for a few more days. It seems odd that just that small change made that much difference.

That doesn't surprise me. The first night I changed my pressure from 10 to 12, I had a hard time getting to sleep. I was used to the lower pressure and going up 2 cm instead of 1 cm was very noticeable to me. When I used my Auto in a range of pressures (10 - 15) for a week, I also had a lot of sleep disturbances with the changing pressures.

Den

Wulfman wrote:

Billmanweh wrote:Well, that didn't go well. For starters, it took me forever to go to sleep. And then I slept poorly and woke up several times. I don't know if that was the CPAP settings or just me. But when I did sleep my AHI was 7.2 (it has been in the low 3's). I guess I'll keep the settings where they are for a few more days. It seems odd that just that small change made that much difference.

That doesn't surprise me. The first night I changed my pressure from 10 to 12, I had a hard time getting to sleep. I was used to the lower pressure and going up 2 cm instead of 1 cm was very noticeable to me. When I used my Auto in a range of pressures (10 - 15) for a week, I also had a lot of sleep disturbances with the changing pressures.

Den

Maybe I should try 11-15 for a few days and then try going to 12-15.

Don't overlook CPAP mode and trying single pressures for at least 3 to 5 nights at a time at each pressure. APAP/Auto isn't for everybody.


Den