Median Pressure Increasing, Why?

[jrcmlc]

When I 1st got my Autoset 2 I set my base pressure to 6, which was below what my old CPAP was set to, which was 8. I felt like 8 was too much and wanted a starting point. I found out pretty quickly that it needed to be higher, based on the median # that was being reported by the software. I went to 7.4 for the base, and then learned from this forum that I should put the base right at the median, so a few months later I adjusted it again to 9 with no epr. This was around a year ago, give or take, and my median at the time was 9.2.

Since then, my median pressure has risen from 9.2 to a pretty solid average of 10.2. Since I don't know that the setting of 8 was working super-well with the old CPAP, I can't say that I started at 8, but my ahi and HI were both pretty low with a base of 7.4 and a median of 9.2...now they are about the same with a base of 9 and a median of 10.2. This seems like a bad thing to me. I haven't changed anything significant at all. Same bed, same wife, same sheets, same pillow, same temperature, same machine, filters are changed regularly, same humidity, eat and drink the same things, weigh the same, same mask, same hose, etc, etc.

So..what's the explanation? Nothing good I bet.

Thanks in advance.

JC

[John M. Browning]

I will be interested to hear the answer to this myself. I have a similar situation happening.

[roster]

You do not complain of any physical symptoms, so it sounds to me that you are getting mentally hung up on a median number that is probably of little significance. If that is all you are concerned about then set your min pressure a few centimeters lower and the median number will go down. But that is just manipulation of numbers and is not considering therapy effectiveness and comfort, so I don't recommend it.

You need to quit worrying about "summary" numbers and start looking at the daily details report. What you want to see on the report is, number one, that your number and duration of events is low. You also want to see a leak line that is low and relatively flat. Finally you want to see a pressure line that is fairly stable and is not making big swings throughout the night.

It's that simple. My therapy is tweaked extremely well (AHI almost every night below 2.0) and I got there by looking at only one report - the daily details. The summary data is pretty much worthless, and in the worse case confusing, toward the goal of effective therapy.

[Pugsy]

Ditto to what Rooster said.

I don't care what my overall average pressure is as long as I see good consistent daily reports. You make no mention of AHI numbers which are more important. The median will rise if the minimum pressure is raised. Law of numbers dictates that.
You can manipulate the median if you wish but it is just a number and there isn't a huge difference. If it bugs you so much, reduce the minimum and watch the AHI, if it is still good and AHI doesn't increase then you will have reduced the median.
Don't sacrifice good therapy for median number though.

[John M. Browning]

Ditto to what Rooster said.

I don't care what my overall average pressure is as long as I see good consistent daily reports. You make no mention of AHI numbers which are more important. The median will rise if the minimum pressure is raised. Law of numbers dictates that.
You can manipulate the median if you wish but it is just a number and there isn't a huge difference. If it bugs you so much, reduce the minimum and watch the AHI, if it is still good and AHI doesn't increase then you will have reduced the median.
Don't sacrifice good therapy for median number though.

I am getting my data capable machine tomorrow, and will be playing with it this weekend, and will see what's up. I have noticed over the past couple of years that I have had to raise the pressure on my base model M-series from 10 to 13, based on quality of sleep. My gf told me that I was actually snoring softly in my mask last night at a pressure of 13. I am very curious to see what I find out this weekend.

[NightMonkey]

Knowing I already have two speeding tickets, my current sweetie asked me last night if I drove carefully on a business trip yesterday. I was happy to report to her that my median speed was 47.5 mph.

She was pleased with that so I did not see the necessity to tell her it was 0 mph at stop lights and 95.0 on a long straight stretch of County Line Road.

[jrcmlc]

Ok. I understand. As far as pressure swings and consistent average AHI #'s, I'm not sure I have that, either. I can look at the averages and they seem to be pretty reasonable, but day-to-day everything moves quite a bit. I thought that was the point of the auto-adjust, to make up for differences (such as a stuffy nose, different sleeping position, etc). Sometimes when I lay on my back my wife reports that I snore softly, but those nights I still dream and feel fine just like any other.

My days vary quite a bit, yesterday was 1.0, .3%, 3.4 with an AHI of 4.4, the night before was 0.6, .2%, 2.0 with an AHI of 2.6.

Also, for anyone who cares to look, here is a sample of this months data:

April 1-27, 2011:

Average usage: 7:21
Apnea index: 0.7
% time in apnea: 0.2
Hypopnea index: 2.7
AHI: 3.4
Median leak: 0
95th leak: 13.2
Median pressure: 10
95th pressure: 11.2

And here is a sample of 1 year ago:

April 1-27, 2010:

Average usage: 7:43
Apnea index: 0.6
% time in apnea: 0.2
Hypopnea index: 3.1
AHI: 3.6
Median leak: 0
95th leak: 6.6
Median pressure: 9.3
95th pressure: 11.2

Thoughts? Not just about the median pressure in the OT, but of the #'s as a whole?

[Pugsy]

Overall both set of numbers indicate quite effective therapy on paper. Not really any huge changes. I would be quite happy with either if it were my data.

If you pretty much see daily AHI numbers less than 5 which it certainly appears to happen, then I wouldn't worry about it.
That median pressure number has varied by less than 1. Which is nothing in the grand scheme of things.

Law of numbers dictates that if you raise that minimum pressure (for whatever reason) the median number will also rise because sometimes you are going to need higher pressures and the median now starts with a higher base.
If you lower the minimum pressure and all other factors stay the same, the median will also lower because of lower base.

It sounds like you are concerned that there may have been some rather drastic changes requiring higher pressures and you are basing that concern on the median number. I don't see it. I would be watching the maximum if that were my concern.
As long as you keep increasing that minimum the median will go up also. Even if everything else remains unchanged till you get to a point that the minimum is more than you need for therapy and the machine doesn't ever need to raise the pressure. But who wants to do that, that is why we use the APAP, so the machine can do a little extra work when needed and let us use the lower more comfortable pressures the rest of the night.

If this median number thing bugs you so much, drop the minimum pressure a bit (not a big drop). Watch to see if the AHI remains fairly stable. Look at it for a week or so since night to night might vary a bit. If AHI is stable, then you might do just as well with the lower minimum and have a lower median.

Personally if I were feeling good, no problems with pressure, getting good numbers and such, I wouldn't give that median difference a second thought. It's just a number and numbers sometimes are just plain numbers...

[roster]

Thoughts? Not just about the median pressure in the OT, but of the #'s as a whole?

As a whole, your numbers look quite good and you might just want to relax and forget it.

On the other hand, if you have any concerns, since you mention snoring on your back, you could look into positional sleep apnea - see viewtopic/t43360/viewtopic.php?f=1&t=43 ... 79#p384179

You are going to need to look closely at the daily details to make any evaluation of positional sleep apnea.

[jrcmlc]

Thanks for the replies.

I read the topic you linked, and I have no doubt that my apnea is drastically increased depending on the position in which I sleep. If I lay flat on my back with no pillow (as I was when that higher # I posted was recorded), and didn't use the machine, I would snore like a freight train and go into apnea almost immeidately, whereas when I sleep on my side or stomach it's a 50/50 chance of snoring and/or apnea (without the machine).

Interestingly enough, the sleep lab said that I did not have apnea on my back (they had me raised up just a bit in the bed).

Also interesting is that night I quote above, the one where I slept flat on my back for 5.5 hours with no pillow (hands above my head, the whole 9 yards), I felt wonderful when I woke up, even though I clearly had pressure beyond normal and more apnea events, and my wife said I snored some and had the "jimmy legs" throughout the night.

Shrug.

JC

[roster]

Interestingly enough, the sleep lab said that I did not have apnea on my back (they had me raised up just a bit in the bed).

Quite a bit of the work sleep labs do is disgraceful.

[jrcmlc]

Ok. Thanks folks.

JC

[pratzert]

Something I've noticed that affects me and may affect others too is the onslaught of Seasonal Allergies.

Yep ! It's that time of the year again when the Pollen count soars and in spite of my taking some allergy medications, I still notice the increased nasal congestion & watery eyes.

More nasal congestion = increase in pressure on the AutoPap.

The swing may be small or it may be larger depending on your sensitivity to the pollen count.

I don't know if that is the cause of your increase... but I thought it may provide some food for thought.