(05-30-2014 04:30 PM)ppowers Wrote: This is a question that I have not found an answer to thusfar on the Resmed S9 AutoPap. OK, it only gives you what you need in terms of pressure, but how does this work. If the machine senses an event, does it immediately go to the highest pressure that the machine is set for, or does it increase the pressure incrementally, 1 cm at a time?
I have noticed that when I obtain my used pressures and AHI info from the info menu, it always says almost the highest pressure that the machine is set to. (machine set at 7-12, pressure ALWAYS 11.8)
I find it a little hard to believe that every night, my max pressure is the same 11.8. Hence, my question. So, again, does it go to the MAX pressure FIRST when an event is sensed, or the incremental question.
Sure would love to know.
Thanks to my helpful fellow pap'rs!
The S9 Autoset watches for several things in the data: Obstructive Apneas, Flow Limitation, and Snore (there may be more, but I know about those). In reviewing my own graphs, I have repeatedly seen events where the machine starts incrementing the pressure in small steps IN ADVANCE of an OA. When I look at the corresponding time in the Flow Limitation and/or Snore graphs, I always see something there that triggered the pressure increase. By contrast, when the machine detects an Apnea that is not obstructive (Central or Clear Airway) there is no adjustment of pressure.
If you are consistently seeing the maximum used pressure at or near the upper limit, that is an indication that the S9 might have used more pressure to counter OAs if the upper limit were increased. This is precisely the situation I found myself in within the first weeks of therapy, and the Dr. authorized in increase from 14 up to 20. After that change the pressure was still running high, in the 19.x area most of the time. Lots of negatives to those pressures: leaking, aerophagia, etc. Then I discovered that most of my OA problem was caused by sleeping on my back. Now that I am doing things to avoid that, my pressures are MUCH reduced. Even though the limits are still 10 - 20 cm, my maximum pressure rarely exceeds 14, and commonly is below 12.
1) Start downloading the data from your S9's SD card immediately. I suggest just copying the entire SD card to a new directory daily. For example, I have a directory named ResData, and within that one named 201405. Within the 201405 directory (or folder if you prefer), I have individual directories named like 20140501, 20140502, and so on. You can and should start capturing this info now, because the S9 erases some of the data after it is more than 7 days old. The detailed flow data is among the most useful to look at to see what is going on, and this is part of what is deleted after 7 days. Read other threads about best practices regarding locking and unlocking the SD card.
2) Get a copy of the open source Sleepyhead software. It runs on MS Windows, Apple, and Linux, so you ought to be able to run it on something. Install it and start looking at your data. Sleepyhead is able to import data from the directories saved as described above.
3) Start looking at the graphs and seeing in detail what is going on during the night. It has been helpful to me to record in a log some basic info, such as date, usage time, AHI, and comments.
4) If you see what I suspect you will find, that the pressure is consistently rising in response to OAs or Flow Limitation detection, and where it would go higher if the upper limit were raised, then discuss with your Sleep Dr. or GP or RT, whomever you have available, to see if they agree to increase the limit.
Then I would start looking to see if there is some factor you can control that might affect the OA rate, such as sleeping position did for me.
Looking at your numbers on the S9 screen only gives you a fraction of the information available - you will be able to see much much more if you download your data and view it in the software.
Good luck in your CPAP journey,