Resmed S9 Autoset erformance changed after fitting Humidifier

Hello,
New member here from Brisbane Australia. Long term APAP user last 5-6 years with S9 Autoset. I'm well used to CPAP and don't use any ramp time. Pressure setting min 11.0 max 14.6. Median pressure reported by OSCAR around 12.

Relatively mild climate here so have never used the Humidifier attachment. Until this year's very cold winter. I attached the humidifier approx Jun 14 and noticed the machine's performance change. I started using a memory card and OSCAR at the same time. Analysis attached.

My issue is that I usually wake between 3.30am and 5. I may attempt to go straight back to sleep or read for a while first. Previously this was not a problem but since fitting the humidifier I find the machine does not supply sufficient pressure to prevent apnoeas and I find myself continually drifting off only to jolt back with a blocked airway. If I persist I may eventually get to sleep but it seems that the machine's algorithm has changed with the humidifier or is struggling to supply enough pressure after being restarted?

I've attached a screen copy of OSCAR analysis. Please advise if more is need or if there is a better way to submit this

Any advice gratefully received thankyou

Peter

Take a picture of the overall Statistics page and make sure to include the bottom of the page where it says "changes to prescription"....or similar wording. I forget exact wording but it is at the bottom of the Statistics page where you see averages for daily, weekly, monthly, etc.
Please share that image.

Post a recent detailed report from a single night where you feel you had problems with the pressure in the middle of the night.

Verify your pressure settings with the humidifier water chamber and without by using a manometer.

Using a water chamber as opposed to the end plate cover shouldn't affect the algorithm at all nor pressure delivered either.

Thanks for the prompt reply Pugsy,

I don't have a scrolling capture tool so here are a series of window captures from last night. I woke at about 3.45am, read till about 5am and then attempted to go back to sleep. I then experienced the repetitive drift off/wake cycles and was unable to go back to sleep. The third capture of daily detail would not attach so I will post it after this post

Last daily capture

For future report sharing check out this thread.
We don't need all those graphs but we do need the stuff on the left side you cut off.
viewtopic/t158560/How-to-post-images-for-review.html

So to be clear you are okay at the beginning of the night and only have this problem when you try to go back to sleep after being awake during the middle of the night?

Go here and learn how to zoom in and check flow rate for arousal/awake breathing vs asleep breathing and look at the 2 OAs flagged after 05:20.
http://freecpapadvice.com/sleepyhead-free-software

You didn't have any flow limitations after you tried to go back to sleep which are a huge driving force for the pressure.
Your pressure didn't go up. You had a couple of OAs but not close together and the machine won't increase the pressure for random OAs without much flow limitations going on.

You did change the pressure max on June 18 but after 5:20 you never came close to it so I don't think that was a factor.

So confirm .....are you having any issues at the beginning of the night or is this issue just when you have been awake in the middle of the night and then try to go back to sleep?

Thanks again Pugsy,

and yes the problem only occurs when I try to go back to sleep after waking during the night - the Resmed has a "cooldown" timer with the humidifier I've noticed so I wait at least long enough for that to complete but I may read for an hour or so. Doesn't make any difference. And the feeling is of marginally insufficient pressure on inspiration such that, when I relax down into sleep my airway occludes and come back awake for a few breaths.

I have thought to increase base pressure from 11 to 12 or so as a workaround but I'm puzzled that the machine doesn't seem to titrate up a bit when it detects the events. But you've said that there's an interval between events beyond which the machine won't adjust so I guess that may be it.

I disconnected the humidifier last night to ensure a full sleep and I will get a few days recording interrupted sleeps without humidifier to compare. Our weather is warming up now so it may be that the problem goes dormant till next winter but I would like to understand OSA a bit better.

I will study those links provided on using OSCAR and posting images but here is the missing summary panel from the images I posted yesterday

crocster wrote: ↑

Mon Aug 02, 2021 2:55 pm

and yes the problem only occurs when I try to go back to sleep after waking during the night -

If the presence of the water chamber changed anything in terms of pressure delivery or algorithm (which it doesn't of course) don't you think it would also affect the beginning of the night too?

I suspect what is happening is you are simply more used to the higher pressures you have been using during the night and once the machine get turned off and you start it up again at the lower pressures then those new lower pressures seem/feel inadequate because your body/brain was used to the higher pressures it was seeing/feeling.

So nothing to do with machine's functions and everything to do with your mind and your perception of things.
Not to make light of what you feel but it isn't because something has changed with your machine in the middle of the night.
What you get in the middle of the night is the same algorithm and pressure you get at the beginning of the night. It can sure feel different though and feel a bit disconcerting.

Some time ago I was using 10 cm minimum pressure for quite a while but decided to do an experiment where I gradually increased the minimum pressure 0.5 cm a week for 6 weeks until I got to a minimum of 13 cm. Spent a week there and then decided to abort the experiment since absolutely nothing changed. When I went back to 10 cm minimum I had 4 or 5 nights where I struggled with feeling like I was suffocating at the 10 cm pressure. I was so used to higher that it took me a while to get used to lower again.

crocster wrote: ↑

Mon Aug 02, 2021 2:55 pm

Thanks again Pugsy,

and yes the problem only occurs when I try to go back to sleep after waking during the night - the Resmed has a "cooldown" timer with the humidifier I've noticed so I wait at least long enough for that to complete

There's no reason to, just put the mask on and go back to sleep, the machine will handle it appropriately.