AHI numbers all over the place

[HOG_Daddy]

Hi all,

Day 6 in CPAP-enhanced life, and I'm still working out some bugs (I assume I'll be in that mode for some time...). My latest quandry is this:

My sleep study titration pressure was 9. I got the S9 Autoset, and it was set to a range of 4 to 10. First couple of nights ran around 1.8 AHI. I tweaked the lower limit (brought it up to 8, and raised the upper to 12), and AHI went up to 3.8. I lowered the limits back to 4 to 10, and got a 1.6, but with lots of leakage from my mouth, (a trend that has started). I rigged up a chinstrap and mouth cover (self adhesive bandage around my chin/top of the head, with a single piece across my mouth, adhered to the vertical portions along my jaw line, to keep my lips closed - I wear a Pure Sleep mouthpiece). Anyhow, one night of that, and my AHI shot up to 4.8 for the first time. No leaks, but certainly not an improvement overall.

Any ideas on what my next step ought to be?

I'm considering making the switch to a FF mask if I can't get this worked out...

Thanks so much for any insight you can provide.

(Edited) Also... what exactly does my S9 do with these events? If it's counting the seconds I'm not breathing... is it ramping up pressure to force open an obstruction, or to kick start a central?

Thanks...

[brazospearl]

HOG_daddy, my first thought is that you need to deal with one problem at a time. I suggest leaving your pressure at
4 -10 and fixing the leak problem. Mask choice and leaks are a hurdle we all have to clear, and your data will not be accurate if you're leaks aren't under control. Also, if you tweak too many things two quickly the data sorta gets muddled and it's hard to tell what created the benefit. Do one thing at a time, and practice patience. And relax, your numbers all look good for somebody who's just starting out.

[dave21]

Okay so I agree, the first thing you need to do is get the leaks under control. If the masks don't work for you and you're a mouth breather then you may need to switch to a full face mask.

Second of all, don't play with the upper limit. Changing the 10 figure isn't going to do anything for you to reduce your AHI. In fact you should really have this set at 20 or the maximum the machine can take. This is the ceiling at which the machine will go to if you get into an apnea event. Having it at 10 means that if you need a pressure of 11 or 12 to reduce and bring you out of an apnea quicker, the machine can't do that because you've maxed the ceiling limit of the machine to 10.

The only reason that you'd want it set at 10 and not say 20 is if you suffer from pressure and you can't take the higher pressure and it causes pain in your lungs, or if you swallow a lot of air in your stomach. Most of us can stomach the pressure (pardon the pun). The other thing is that if you suffer from Central Apneas some patients can find the higher the pressure the more Central Apneas they have occur, so sometimes this is another good reason why you might not want to have the maximum set at 20 or what your machine is capable of. Most of us just leave it at what the machine is capable of though if we don't suffer from any of the above.

Increasing the bottom figure gradually, e.g. I have my bottom figure at 10.6 now will have the effect of permanently giving you more pressure that splints open your upper air way and that will keep the apneas at bay, so it's the bottom number (first number) you need to be changing slightly.

If you're going to be playing with changing the pressure, you might also want to take a read of some topics I put together at http://www.osahelp.com/#10 (and above this as I have a lot of graphs and that might help you out more). As always, remember what you have set initially, and when you make changes, give it 3-4 days before you make another change because other things can cause different things to occur night in night out.

(Edited) Also... what exactly does my S9 do with these events? If it's counting the seconds I'm not breathing... is it ramping up pressure to force open an obstruction, or to kick start a central?

The idea is that if an event occurs with an Auto machine it will detect the event, ramp up the pressure to respond more quickly, and reduce the time you're in an apnea. For most of the medical profession they tend to think this is okay and to have the minimum figure at a low figure, e.g. 6 or 8. However over time if you notice like me that by using ResScan and that most of your Apneas then need a pressure of 10 or 10.5 to reduce and bring me out of an Apnea, then setting the machine to 10.6 means that if I have an Apnea that requires 10.8 to reduce and respond then it's a lot quicker to respond as there's only a 0.2 difference for the machine to ramp up. If I had to ramp up from 8 (which is what my sleep doctor suggested) my 12 second Apneas would be more like 45 seconds apneas.

When using a fixed pressure machine (non-Auto) what happens is that you are titrated at a figure that reduces most of the Apneas (but not all), so with this school of thought I setup the Auto part of the machine with the minimum pressure to be close to my average Apnea. This has an effect of not only reducing the amount of Apneas I have in a night and reducing my AHI figure but also allowing the machine to respond much quicker and only having to RAMP up the pressure a small amount to have it become 100% effective.

Hope this helps, check out http://www.osahelp.com that I put together, I think you'll find it a good read and it will answer most of your questions.

Thanks
Dave

[HOG_Daddy]

Great info, Dave! Thanks for this.
Lots of learning to do here.

I've already changed to the Ultra Mirage FF mask, so at least the leak problem should be resolved. First night with the FF and a CPAP of 9.0... my highest AHI level to date. I'm going to give it a few days to normalize, then start back in the auto mode to find what my limits should be.

Appreciate it!

Steve