Higher pressure leading to higher AHI?

copygirl · Post by **copygirl** » Wed Oct 12, 2011 4:36 pm

Hello,
I've appreciated the wisdom on this board for a few years and I'm back to ask another question.

I have a Respironics bipap set at 10/4 (at least I know the ipap was 10; I think the epap was 4). My AHIs have consistently been about 6 per hour (AIs virtually 0) so I've been trying to "self-titrate" by increasing my pressure. I slowly went up to 10, then 11, and the numbers didn't get much better. AHI about 9 I think. Then, last night, I decided I'd go up to 12.4. And AHI was 16! Whoa! Strange thing is, I feel fairly rested, though a little spacey. (Also of note, the machine pushed the epap up to 7, I think.)

Any idea why increasing my pressure would actually make my AHI *worse*? I have no leak problems with my mask. I have, however, been having a stuffy nose, so I wonder if that impacts things. (I think I've developed allergies in my 30s.)

I know I need to get another sleep study/titration, but I just can't afford the $850 out of pocket right now.

Should I keep going up and see what happens? Or back down to 10? Thank you!!

JohnBFisher · Post by **JohnBFisher** » Wed Oct 12, 2011 4:43 pm

Increasing the pressure can trigger complex apneas. Essentially as the pressure increases you start to have central apneas. This is one cause.

Perrybucsdad · Post by **Perrybucsdad** » Wed Oct 12, 2011 6:06 pm

There was a great post a little while back from Firehope that demostrated that a lower pressure sometimes can lead to a lower AHI. Interesting read.

viewtopic.php?f=1&t=68846&p=639694#p639694

copygirl · Post by **copygirl** » Wed Oct 12, 2011 10:22 pm

Thank you both! I'll go check out that thread. I think that tonight I'll lower my ipap back down to 10 but up the epap to 7 or 8.

sickwithapnea17 · Post by **sickwithapnea17** » Wed Oct 12, 2011 10:52 pm

I'm finding though that my pressure of 18/14 reduces the clear airway apneas which may be central apneas- anyone know the reason for this?
also what should I set the Ti to?

DaveLP · Post by **DaveLP** » Fri Oct 14, 2011 8:59 am

My titrated pressure was 9 in my sleep study. I found after buying and auto machine that at a fixed pressure of 9, I was at an AHI of 15 at times. Most of my AHI has always been hypopnea and most nights I have no obstructive apnea. I have experimented with various ranges and found that a range of 9-11 works well at times, but sometimes I pop up into the double digits after being 4.5AHI on other nights.

Mouth leaks with nasal pillow masks contribute to this and the higher the pressure, the more I see exhale puff index (EPI) rising. Last night, I was in good territory for 4 hours and the last hour of sleep showed my pressure rising up and bouncing briefly at the 11 pressure. I experienced some EPI and a snoring episode during this period and it drive my AHI up to 10.5 after staying below 3 for most of the night.

Mask type, whether or not you use a nasal mask or a full face mask can enter into the equation. Mouth leaks will throw off the readings and inhibit your machine from being able to respond. It's kind of like blowing up a balloon that has a small hole in it. A chin strap can help if you are using a nasal mask. Some here use blue painters tape or surgical tape to keep the lips closed. I have a very short beard, but it interferes with taping or the use of a full face mask.

Mary Z · Post by **Mary Z** » Fri Oct 14, 2011 12:18 pm

One thing that I would point out is that one night does not indicate a trend. Increasing your pressure may be having the effect of increasing your AHI, but I would give it more than one night before I came to that conclusion.

70sSanO · Post by **70sSanO** » Fri Oct 14, 2011 2:50 pm

You need more than one night to see what is happening.

From my personal experience over 3 months I increased my pressure (CPAP) from 13 up to 17 under theory that the higher the pressure the better the therapy. Keep in that this was over a 3 month period.

My AHI went up, not just the centrals, but also the obsturctive apneas. Also they were a lot longer and more clustered. I'm back down to 13 and I'm doing better, lower numbers, sometimes not as low as I would like, but I'm running close to an AHI of 5 with about 3 in centrals and 1 or so in obstructives; hypopneas are less than .5.

The centrals are the crazy thing. I'll sleep for 5 or 6 hours and have an overall AHI that is less than 3. If I go back to sleep for another hour or 2 I can tack on another 1.0 to 2.0 in centrals.

John

copygirl · Post by **copygirl** » Fri Oct 14, 2011 9:23 pm

I decided to bring my ipap pressure back down to 10 like normal, but increase the epap pressure to 8. (I think it's been either 4 or 7). First night with that, AHI of 10. Second night, AHI of 6. I'm going to stick with these settings for at least a week and see how it goes.

I am trying to learn more about whether the epap or ipap prevents apneas. For some time I thought the epap didn't really matter; it was just lower to make exhaling easier. Now I'm reading otherwise. Does anyone have any good links to help me learn more about this?

sickwithapnea17 · Post by **sickwithapnea17** » Fri Oct 14, 2011 11:19 pm

I tried different bipap settings of bilevel 10/4 and 15/11-18/14 and the AHIs were lower on the 15/11-18/14 higher pressure for some reason. I have mostly hypopneas now on bipapst though I was getting a lot of clear airway apneas on the bipap

Higher pressure leading to higher AHI?

Higher pressure leading to higher AHI?

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