Variable AHI on APAP

Hello everyone! Hope you're all doing well today.

I was diagnosed with mild sleep apnea a few months ago, but started treatment only relatively recently. It has been about 7 weeks that I've been using an APAP machine - not mine, just a trial for now until I get a second sleep study - and I keep up-to-date on my data using the Sleepyhead software.

The sleep apnea I was diagnosed with was rather mild. On the night of my sleep study, I had an AHI of 6.7, all consisting of hypopneas, and all happening while I slept on my back. I am not sure that the data collected was entirely accurate, but anyway. Since I started using the machine, my AHI on the machine has progressively gone from very low numbers, 0.1-0.9, to higher numbers, 1.0-1.9. No big deal, I figured. Last night I had an AHI of 3.37 - the highest it has ever been on the machine. Just the day previous, my AHI was 0.38. As you can see, the numbers are quite variable. Also, the 90% and average pressure has been increasing (PS. I have not been gaining weight - in fact, I have been losing and have lost quite a bit since before I started treatment). I've attached some images from Sleepyhead here:

AHI of 0.38:


AHI of 3.37:


AHI progression over time:



I guess my question is, what does this mean? Why am I having some nights with more apneas than others, and why isn't the APAP resolving these? I remember I asked the CPAP tech why I would have any apneas at all on the machine, and she said it was because they did not want to "over-titrate". I don't understand what it means to "over-titrate" in this sense - would we not want to get rid of all apneas?

I'm sorry, I know I'm such a newbie, but I would totally appreciate any and all help! Thank you so much! (Guys, by the way, this forum is great.)

We don't sleep the same way each night. It's normal to have AHI variable numbers and we don't normally worry about them unless they vary hugely and often.

The 2 most likely culprits for an increase in AHI (and maybe little clusters of events like you see with your OA cluster on the little higher AHI night) are supine sleeping or REM stage sleep or maybe combination of both.
It's common for our OSA to be "worse" when sleeping on our backs...when in REM stage sleep or both and often we just need more pressure during those time to better prevent the airway collapse.
When using APAP mode...this usually means a little more minimum pressure. The machine can't/doesn't respond to the collapse of the airway in the blink of an eye fast. It just doesn't work that way.

We don't expect to totally eradicate all apnea events. It's an unrealistic expectation really and will drive a person crazy trying to get there and remember...sometimes the machine records "false positives" too. Some people do get AHI 0.0 fairly often...others don't. Even people who don't have OSA can have occasional apnea events too.

Also you are using EPR and looks like at 3 so during exhale the pressure is dropping by 3 cm and maybe that drop is causing the pressure to go low enough to allow the airway to collapse a little. Sometimes reducing EPR helps reduce the OAs that might happen.

If this "bad" night (which is still quite acceptable) was common place then you might want to do something to better hold the airway open but if it is a rare occurrence there is really no need to do anything.
We don't know if it is related to supine sleeping or REM sleep unless you know you never ever lay on your back.

Remember...the CAs are centrals and we have to mentally remove them from the pressure evaluation because we don't treat them with more pressure with the APAP/CPAP machines anyway.

A couple of different thoughts on this.

The first is that your use of xPAP is helping and you are beginning to enter deeper stages of sleep. Prior to this your arousals would prevent you from these deeper stages. As you enter these deeper stages of sleep you experience a few more interruptions, but wake up more refreshed.

The other thing to keep in mind is that life is variable. Each day is a little different and each nights sleep will have some variation. Tracking your numbers you should see that they end up in a range. You don't need to be concerned until the bulk of the numbers begin to exceed that range. There will always be some spikes here and there so don't be too concerned about those. Also keep in mind that a weeks data may have more variability than a years data.

Thank you so much Pugsy and Hosecrusher! I figured that part of this was me being anxious and over-analyzing the situation, but I guess I just wanted to double-check that it's nothing really to worry about.

I'm not entirely sure that I am feeling better or more well-rested, but I am definitely having way more dreams than before, so that lends more evidence to both your responses about REM sleep/going into deeper stages of sleep (i.e., you generally won't enter REM sleep if you don't first enter stage 3/4). I wonder, if I truly wanted to put in more effort into figuring this out (which I probably shouldn't), if my nights with increased AHI correlated with the nights during which I can remember more dreams.

Thank you for your responses! I truly appreciate how helpful people can be.

del

avi123 wrote:By deciding on your own to use an APAP you're taking a big risk b/c use of APAPs are contra indicated in cases of 1) Central Sleep Apnea Syndrome (including Periodic Breathing and CSR) 2) COPD 3) Heart Problems 4) Weak lungs (hypoventilation). In such medical conditions APAPs could be ruinous.

You are making unwarranted assumptions. Many people are prescribed temporary rental machines by their doctors pending titration.

you're taking a big risk b/c use of APAPs are contra indicated in cases of 1) Central Sleep Apnea Syndrome (including Periodic Breathing and CSR) 2) COPD 3) Heart Problems 4) Weak lungs (hypoventilation). In such medical conditions APAPs could be ruinou

Alarmist Avi.

Thanks for your concern, Avi. I'm not using the machine on my own - I am both doctor- and "machine tech"-supervised. What happened was that I had a sleep study, and prescribed an APAP trial. Once I decided to move forward with purchasing a machine, I was told that I would need to have a second sleep study for titration purposes. I promise that I am quite conscientious about my health and otherwise, and am not doing anything to compromise that. I apologize if my post was lacking in necessary details.

ChicagoGranny wrote:

you're taking a big risk b/c use of APAPs are contra indicated in cases of 1) Central Sleep Apnea Syndrome (including Periodic Breathing and CSR) 2) COPD 3) Heart Problems 4) Weak lungs (hypoventilation). In such medical conditions APAPs could be ruinou

Alarmist Avi.

that's why avi's in my ignore list

I recommend it.