Adjusting For Weight Loss Pt 2

[owleyes]

Early in the year I made a post asking if I should adjust my cpap pressure due to having lost weight. It was suggested that I could try lowering it gradually and then checking my progress. My machine was set to 15 Minimum and 20 Maximum. I made several changes over many weeks, but finally decided to leave my minimum at 11, where it's been for several months. A few days ago I changed the minimum to 7 and now I see that as my lower setting decreases, so does my pressure during sleep. I'm not sure if that's good or bad.

Fast forward to last week. I stopped in to visit my (new) therapist after a couple of years (insurance, etc). I'll be making a formal appointment shortly. But in a brief conversation, I described what I've done with my settings. He said there is no need to change the setting because if it's set to AUTO, it should fluctuate between 4 and 20 as needed.

I don't know if he's confused, but I know I am.

[Pugsy]

The machine (when in auto mode) will only increase the pressure when it senses a need to increase it.
The reasons for an increase....snores, flow limitation, obstructive apnea and hyponeas.
Technically the person who told you that 4 min and max 20 was correct.

How effective that 4 to 20 setting ends up being is how high the machine needs to go to hold the airway open and prevent the airway tissues from collapsing. It works good if a person only needs maybe 8 or 9 cm to keep the airway open but won't work so great if a person needs say...14 cm because it takes too long to get from 4 to 14.

So technically he wasn't confused but he didn't explain the whole story either.

If you are now using 7 cm minimum....what does your pressure graph look like? Does it increase much? If not, you could try lower again and see if at some point you start having apnea events in numbers that are problematic.

I use a 4 cm exhale pressure and 8 inhale pressure on my machine....in auto mode I seem to average around 9 or 10 inhale except for when I am probably in REM and I sometimes see 16 cm inhale when probably in REM where my OSA is known to be worse and I just need more pressure.

[owleyes]

I thought I posted my graph. I'll try again.

2021-11-07 at 3.59.18 PM copy.jpg (859.27 KiB) Viewed 925 times

[Pugsy]

How are you sleeping and feeling?

I don't know that I would try going much lower than the 7 cm minimum.
You are using a Respironics machine and it doesn't respond very quickly.
Sometimes you need around 10 cm....probably either related to sleeping on your back or maybe REM stage sleep.
If you were using a ResMed machine you might get by with a little lower minimum because its auto adjusting algorithm responds a bit quicker than Respironics.

You can see that despite the 20 max...it never gets close to the max so it really doesn't matter what the max is.

The minimum pressure setting is always the most critical setting since it does the bulk of the work holding the airway open.

[owleyes]

The line seems to go to whatever minimum I have set. So what tells you that 7 is low enough?

Just trying to understand.

Thanks.

[Pugsy]

The minimum pressure line is always going to start or go where you have the minimum pressure setting at...and then from that point the machine goes up when it senses snores, FLs, OAs or hyponeas.
If you look at the pressure graph it goes up and down from the 7 cm because it is sensing the airway collapsing.
You are having some OAs and hyponeas when the pressure is above 7 cm...AHI over 2 and mainly OAs and hyponeas.
If you go with much lower of a minimum your OAs and hyponeas may increase because the machine might not be able to get to where it needs to be to prevent those OAs and hyponeas quickly enough.

If you are sleeping good and feeling good then I would give this setting some time and see what happens.
If you aren't sleeping good and feeling good then maybe a little more minimum is needed.
I don't know if this AHI is high enough to disturb your sleep or not. For some people they wouldn't feel so good with AHI of 2.83.

[palerider]

I don't know if he's confused, but I know I am.

The correct word is "ignorant", not "confused".

As in "your therapist is ignorant of the way that an auto CPAP works.

[owleyes]

If you are sleeping good and feeling good then I would give this setting some time and see what happens.
If you aren't sleeping good and feeling good then maybe a little more minimum is needed.
I don't know if this AHI is high enough to disturb your sleep or not. For some people they wouldn't feel so good with AHI of 2.83.

I see. My AHI was better at min 11, but I've noticed that whenever something changes, it usually takes a week or more for the AHI to adjust. Is that just me?

But now that I think about it, I may be a little off today. The past 3 night's have been hovering near 3. Maybe I'll bring it up to minimum 10 for a few weeks and see how that compares with the 11 I was at for the past few months. My AHI had been below 2 on average and below 1 sometimes.

- Steve