Auto CPAP management

I have a new Dream Station. The first night I used it, it was on factory settings and full auto. My 90% pressure was like 10.5. (it was 14 on my non-auto cpap) So the next night I set my minimum pressure to 10. Then, the 90% pressure was 12. I set the minimum pressure to 11. Then the 90% pressure went up again. Last night I had it set on 13.5 and my minimum pressure was 15 . It seems to keep going up as I raise the minimum pressure closer to my previous prescription. Any ideas why this might be? I don't think I'm sleeping as well with this as I did my regular, non-auto machine either. thanks

I recently switched to auto cpap. I posted my data and questions here viewtopic/t155224/Please-review-my-data.html

Hopefully knowledgeable people will weigh in.

It is not surprising that moving up the lower bound will push the 90% number higher since you raised the floor.
If you have not yet done so, use sleepyhead and the SD card to look at every breath and overall stats.

Perhaps someone can point to a thread which discusses how to tune the auto cpap treatment based on data.

You missed something - 90% represents the upper limit of what happened - everything UP to 90%, not 90% of the whole time... it's 90% or below.

TedVPAP wrote:It is not surprising that moving up the lower bound will push the 90% number higher since you raised the floor.

that's not what it means.

http://adventures-in-hosehead-land.blog ... de-to.html

Julie wrote:You missed something - 90% represents the upper limit of what happened - everything UP to 90%, not 90% of the whole time... it's 90% or below.

Not sure if you are referring to my post or not, but I do not understand what you are saying.

palerider wrote:

TedVPAP wrote:It is not surprising that moving up the lower bound will push the 90% number higher since you raised the floor.

that's not what it means.

http://adventures-in-hosehead-land.blog ... de-to.html

Not sure if there is a disagreement. Replace my word of bound with limit. Then is it clear?

TedVPAP wrote:

palerider wrote:

TedVPAP wrote:It is not surprising that moving up the lower bound will push the 90% number higher since you raised the floor.

that's not what it means.

http://adventures-in-hosehead-land.blog ... de-to.html

Not sure if there is a disagreement. Replace my word of bound with limit. Then is it clear?

no.

raising the minimum doesn't have any direct correlation with the 90% number.

Ted

The 90% is the number which 90% of the readings are <=. it is not a bound or limit per say. it just tells you where your pressure lies 90% or the time. Whether the numbers lower than the 90% number are 4 or 5 or 10 cm lower is not material.

With sleepyhead, you should be able to see what your pressure was most of the time. The 90% (or 95%) numbers are arbitrary cutoffs.

For instance if you're at eleven 85% of the time, at fifteen 5% of the time, and above that 10% of the time, your 90% number would be fifteen. Likewise, if you're at fifteen 85% of the time, lower than that 5% of the time, and higher the rest of the time, your 90% number would still be fifteen.

TASmart wrote:The 90% is the number which 90% of the readings are <=. it is not a bound or limit per say. it just tells you where your pressure lies 90% or the time. Whether the numbers lower than the 90% number are 4 or 5 or 10 cm lower is not material.

Actually it is NOT where your pressure was for 90% of the time...it is a number where your pressure was at OR BELOW for 90% of the time. The "or below" part of the definition is very important.

90% numbers are easily skewed by the slightest amount of time at a higher pressure and they really don't mean a lot short term...now long term maybe but that's months not days long term and usually long term the 90% pressure comes in close to the overall average pressure.

Here's a good example of how 90% numbers are easily skewed.
The 90% is quite high but it is very obvious that I was only up there for a relatively short period of time. The bulk of the night the pressures were well below the 90% number.

Absolutely Pugsy, I mis-wrote. AT or below it is.

twdc33 wrote:Any ideas why this might be? I

90/95% numbers can vary widely for any number of reasons. Mainly because we don't sleep the same each night for any number of reasons plus they are easily skewed high by the least little bit of time at a higher pressure.

Since you used fixed cpap pressures for a long time it doesn't surprise me that you don't feel like the sleep is as good with the auto adjusting pressures.
Plus you started out at a much lower pressure than you were used to. So your body has been used to one thing and you throw in a bunch of new stuff for it to get accustomed to....might be better to go back to the way it was (or close to it) and ease into changes.

Try setting the machine in apap mode to minimum of 14 and maximum of 14. That will allow it to function like your fixed pressure but still turn on the FL flagging (which is turned off in cpap mode).
See how you do and then if you want to try apap mode try it with a really tight range something close to what you were used to using...like minimum of 13 and max of 15....and gradually open up the range after spending a few nights at the new settings to get the body used to the new settings based on what you see or don't see on the software reports.

Quit worrying about the 90% number...it's just a number that varies a lot and doesn't mean much of anything except maybe long term....like 6 months or more long term.

TASmart wrote:Absolutely Pugsy, I mis-wrote. AT or below it is.

No problem. I thought (while scratching my head) "he knows about the or below" part...
I have done the same thing...omitted typing the "or below" part. My mind was thinking it but fingers didn't type it...that happens a lot with me.
Brain works faster than fingers.

The rise in 90% number could simply be because of the rise in min. The cpap is reacting and working better by allowing it to rise to the higher pressures needed. DS is said to need a higher/closer to 90% min pressure to react. I would keep it set 2cm under the 90%, as you adjust it over a couple of weeks

I don't advise using the 90 % pressure number as any sort of guide unless you have 6 months of 90% numbers.
The 2 cm below the 90 % number isn't any sort of guide.
If we used that then I would need a minimum of 14.5 (see the report of mine above) and that would mean I would use nearly 5 cm more all night when it's obvious it isn't needed.
Now long term...it works out because I did a long term average of the 90% numbers and I came up with 11.8 which just happened to be right about where the overall average is. So 2 cm below the long term average 90%...works out well but short term there's just too much potential for skewing of that 90% number.

Changing pressures nightly based on one night 90% number will do nothing but make a person get quite good at chasing their tail.

90 % numbers aren't the holy grail of anything and they are too easily skewed to put much faith in them on a night by night basis.

If someone just has to have some sort of number to go with ...use the overall average and not the 90% number.