How I set the pressures on my APAP machine on my own


    First a disclaimer: I’m a person who has purchased and set an APAP machine on my own. I’ve achieved clinical relief, which means that I have successfully treated my sleep apnea with a machine but I actually still have it (without a machine). I’m not a doctor, just a retired science teacher who gets along with experimentation and quantitative data. So, look at the info and  use it as you deem fit. Who knows. I may have it all wrong!

    When explained to me, the ‘jargon’ got in the way of my understanding of some of this stuff. So, I’ll try to use plain english when I can.

    With an APAP machine (Automatically adjusts the pressure you need instead of one fixed pressure used in CPAP machines. A for automatic, C for continuous) there are Two pressures. A higher one, and a Lower one. A poor analogy might be to think of it like a high jump bar in the olympics. Even though an olympian may never jump much more than 7 ft, they still build the mechanism to set the bar up to 10 ft should anyone ever go that high.

    When I first got my machine I really didn’t know where to start. I did begin by learning how to set my two pressures and use a program like Sleepyhead in my computer to read the data from may APAP machine on my SD card. You’ll have to do that too for yours. It’s not exactly the same procedure on all APAP machines.

    Then I decided to do a sort of random set of settings to start off with. I started too low with settings of 5 and 8 which gave me an AHI of around 19. Not horrible, but pretty horrible. AHI by the way is that number you’re trying to get down. It’s a reading of how many obstructive events you’re having per hour. The consensus is anything under AHI 5 is clinically treated. But lower is often better.

Example of an AHI reading from the Sleepyhead program

    Over a period of nights I eventually worked my way up to pressures of 8 and 12. So, what does that mean.... The high number is the limit of  how much pressure you might need if your throat is really closed up. It usually doesn’t need that much pressure but it might. CPAP machines use this lone number. And it works. The thing is that yes,  you will have to breath at that fixed pressure all the time. Thats when the air goes out through the little holes in your mask. Doing that can be uncomfortable for some people.

    With an APAP machine you have an auto adjusting pressure within a set range. Much more comfortable this way. Hence, when I breath, and if it detects my throat is closed, it increases it up to a possible 12.  It auto-raises the pressure, if needed, just the right amount to open my throat.

Setting the machine

First: Find out what your high end pressure is.

    For some people it’s 10. For others it might be 18. The machines can go up to 20. It’s individual for everyone. I experimented and decided on 12 for my high end. I noticed that sometime I actually hit 13, but very infrequently. These days my pressure is set at 13. Below you can see a reading from Sleepyhead. The read line shows my high pressure. Most of the time it’s 12 or less. Once it hit 13 (the flat top section). I could set it at 13.5 or 14 but 13 is high enough for 98% of my night.

    So, lets say that you decide on a setting of 12 for the high end. For now, set your lower number to 8 (or 4 less than your high number). Sleep a few nights this way and see if your setting of 12 is enough so your graph doesn’t top off a lot. You need to adjust it so your high end number keeps the red lined graph within the graph boundaries (most of the time). Keep that high number so that it’s just what you need. If you never get above 13 don’t set it at 16 for example. If the red line never comes close to the high number (top of the graph) then lower it so it mostly stays just within the graph boundaries. This could take several nights to tweak it just right. Note: as you change the high number adjust the low number to within 4 of it.

Second: Find out what your Low end pressure is.

    Now that the high end number is set. start off by setting your low pressure number 4 less than the high end. (You’ve probably already had this setting.)

    Each night Pay attention your your AHI number. For example’s sake, lets say your AHI is 4.5. Pretty good but you might be able to get it lower. Since you can have better nights than others at the same setting, sleep a few nights at this setting and see if it’s fairly consistent. Then you can tweak it. Try raising your lower number incrementally up a bit. Then after a few nights, see if that made a difference.

    In my experience,  the separation of  around 3-4 between high and low pressures settings seems to often be best.

Why it’s important to keep the low pressure setting within 3-4 of the high pressure setting.

    An APAP machine can  adjust it’s pressure but it can do so effectively and fast enough to make a difference only if it doesn’t have to adjust too much. You know you’re going to need a higher pressure to get that airway open, so you need to set the low (relaxing) pressure not to far away from the higher one so it can get there in time and do it’s job.

Why periodically checking your AHI periodically is a good thing

    These days I have my Phillips Respironics machine set at 9 and 13.5. My AHI is under 2 which is pretty good for me. I feel rested at those settings. But, as the seasons change, allergies kick in, I get older, etc. I keep a periodic watch using my computer and the Sleepyhead software and sometimes tweak my settings to manage them.

    I noticed for example, that as winter came on in Maine, and we closed up the house, and my usual winter post nasal drip reared it’s head, my AHI numbers crept up into the 3-5 range. At this time I begin taking a shot of Flonase in each nostril once a day and my AHI drops down again. In the summer with the fresh Maine air running through the house, I don’t need to do this and my AHI is mostly 1 or less.

So in recap:

  1. 1.Find out how to adjust the high and low pressures on your APAP machine and how to get that data into the Sleepyhead software.  It can be done without Sleepyhead by reading your AHI on your APAP machine but it’s more guesswork.

  2. 2.Sleep successive nights to find out how high you need to go for your high end pressure setting.

  3. 3.Sleep successive nights to see what the best (usually within 3-4 from the high pressure) your lower pressure needs to be.

This has worked for me. Your mileage may vary. Heck, I might be completely off base here, but for what it’s worth...

Thanks for reading,