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Newbie wondering why AHI fluctuates so much - Printable Version

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Newbie wondering why AHI fluctuates so much - Bxbomber - 03-20-2017

Hello everyone! Was recently diagnosed with moderate apnea and have been reading and trying to become familiar with everything associated with sleep apnea. This forum has been a tremendous help! I operate subway trains and therefore must be treated in order to continue working.

I received my Airsense 10 Autoset on Feb. 27 and have used it every night since. Feel fortunate that I haven't had too much of a problem getting used to sleeping with a nasal mask (airfit N10). The machine is set on APAP with min. set at 4 and max at 16. EPR is set full time at 3.


What I don't understand is why my AHI fluctuates as much as it does? Inside of a week it's been as low as 0.92 to as high as 6.75 last night. Is this normal as my body continues to get accustomed to the therapy? Thoughts? Advice?

Again a big shout out to everyone here helping and sharing their knowledge!


RE: Newbie wondering why AHI fluctuates so much - chill - 03-20-2017

Welcome!

We all get some variation, but that is probably a bit on the high side.  I usually vary between 0.5 and 2.  Several things can affect this:
  • Position is probably the most likely.  Sleeping on your back can result in a higher AHI as your tongue tends to fall back a bit more.  Chin tucking results in narrowing your airway and more events.  Wearing a soft cervical collar is one way to prevent this.
  • Some medications can affect AHI
  • Drinking alcohol can cause a higher AHI
  • Being awake and wearing the mask can result in a higher AHI as awake breathing can mimic sleep disordered breathing
Take a look in SleepyHead at the nights it is higher.  What is going on?  More snoring?  Flow limitations?  Hypopneas?  etc.

And this may settle down as you grow more accustomed to the therapy.


RE: Newbie wondering why AHI fluctuates so much - Bxbomber - 03-20-2017

Hi Chill! Thanks for your input! I've been trying to sleep on my sides instead of my back and not tucking my chin based on everything I've read here on the board. You said "Being awake and wearing the mask can result in a higher AHI as awake breathing can mimic sleep disordered breathing" is something that may be happening.

I'm usually in bed by 8:30 PM and up around 3-3:30 AM for work. Usually watch a little TV in bed and doze off. Also on my days off I do tend to wake up early but stay in bed trying to fall back to sleep. Should I not wear the mask and/or remove the mask and turn off my machine when this happens?


RE: Newbie wondering why AHI fluctuates so much - Sleeprider - 03-20-2017

BXbomber, I would guess that it is your minimum pressure rating that is the problem, especially with EPR at 3. Here is what happens. The minimum pressure of the machine is 4.0 cm, so you start out at 4/4 pressure (IPAP/EPAP). As pressure increases it becomes 5/4, 6/4, 7/4, 8/5, 9/6. I'm not going to get into why that is messed upt, but take my word for it.

Set your minimum pressure to the median or average pressure you have for the last 7 or 30 days...doesn't matter. If it is less than 8.0 cm, set EPR so that the minimum pressure will be 4.0. In other words, for a minimum pressure of 6, set EPR at 2. When you get a chance, post some data and I'm sure we can come up with something even more brilliant.


RE: Newbie wondering why AHI fluctuates so much - chill - 03-20-2017

(03-20-2017, 02:42 PM)Bxbomber Wrote: Should I not wear the mask and/or remove the mask and turn off my machine when this happens?

I wear my mask anytime that I might fall asleep / fall back asleep.  But I don't sweat it if that results in a higher AHI as I know the number is likely bogus.  Try to focus on how you feel and not on the AHI.  It is not some magic number, it is just a very, very crude yardstick.  If you almost stop breathing (hypopnea) once an hour for 10 seconds each time that gives you an AHI of 1.   If you completely stop breathing (apnea) once an hour for 120 seconds each time that gives you an AHI of... 1.  Clearly those will have very different outcomes for your body.


RE: Newbie wondering why AHI fluctuates so much - Bxbomber - 03-20-2017

(03-20-2017, 03:27 PM)chill Wrote: BxbomberShould I not wear the mask and/or remove the mask and turn off my machine when this happens?

I wear my mask anytime that I might fall asleep / fall back asleep.  But I don't sweat it if that results in a higher AHI as I know the number is likely bogus.  Try to focus on how you feel and not on the AHI.  It is not some magic number, it is just a very, very crude yardstick.  If you almost stop breathing (hypopnea) once an hour for 10 seconds each time that gives you an AHI of 1.   If you completely stop breathing (apnea) once an hour for 120 seconds each time that gives you an AHI of... 1.  Clearly those will have very different outcomes for your body.


Makes sense chill! I appreciate you taking the time to share your expertise with me!


RE: Newbie wondering why AHI fluctuates so much - Bxbomber - 03-20-2017

(03-20-2017, 03:14 PM)Sleeprider Wrote: BXbomber, I would guess that it is your minimum pressure rating that is the problem, especially with EPR at 3.  Here is what happens.  The minimum pressure of the machine is 4.0 cm, so you start out at 4/4 pressure (IPAP/EPAP).  As pressure increases it becomes 5/4, 6/4, 7/4, 8/5, 9/6.  I'm not going to get into why that is messed upt, but take my word for it.  

Set your minimum pressure to the median or average pressure you have for the last 7 or 30 days...doesn't matter.  If it is less than 8.0 cm, set EPR so that the minimum pressure will be 4.0.   In other words, for a minimum pressure of 6, set EPR at 2.  When you get a chance, post some data and I'm sure we can come up with something even more brilliant.

Hello Sleeprider! First let me say that as I've been reading and trying to educate myself about sleep apnea I've found you to be one of the most knowledgeable persons on the subject and truly appreciate all the assistance you provide for us all! I will do as you say and adjust my settings. I will post my sleepyhead data within the next day or two.


RE: Newbie wondering why AHI fluctuates so much - trish6hundred - 03-20-2017

Hi Bxbomber,
WELCOME! to the forum.!
Good luck to you with your CPAP therapy, hang in there for more responses to your post.


RE: Newbie wondering why AHI fluctuates so much - Bxbomber - 03-20-2017

Hi trish6hundred! A pleasure to meet you! Thanks for the encouraging words!


RE: Newbie wondering why AHI fluctuates so much - Ockrocket - 03-21-2017

Welcome aboard the Apnea Board BX.. 

If you are having trouble staying on your side to sleep, and old trick was to sew a "pocket" on the back of a pajama top and put a golf ball or other similar sized object in there.. the idea is that when you roll on to your back it causes discomfort and makes you roll back on to your side.

Another trick was to sew a cotton reel on the back to have a similar effect.