CPAP, Arousal threshold & BMI

[ElusiveSleep]

I’m new to the forum. Started APAP (ResMed AirSense 10) about 2 months ago for moderate OSA (AHI = 19). To my surprise, next day alertness and feeling rested has been elusive even though my AHI is typically between 2 to 5.

My BMI is ~25 (high end of normal) and I appear thinner for my current weight. After much digging, I discovered a research article (citation below) regarding the effect of BMI on CPAP compliance. Compared to obese OSA subjects, those with BMI < 25 were significantly less compliant to CPAP use (36% vs. 13%) and had a low respiratory arousal threshold compared (86% vs. 60%).

Would like to hear thoughts, comments from others about their own experience regarding BMI and CPAP compliance.

[Gray EL, McKenzie DK, Eckert DJ. Obstructive Sleep Apnea without Obesity Is Common and Difficult to Treat: Evidence for a Distinct Pathophysiological Phenotype. J Clin Sleep Med. 2017;13(1):81–88. Published 2017 Jan 15. doi:10.5664/jcsm.6394]

[Miss Emerita]

Welcome, ElusiveSleep. I have nothing to contribute on the general subject of BMI or compliance. I think any individual will have little to go on but their own experience. I have a normal BMI and have been 100% compliant, for example, but that doesn't signify in relationship to the study.

What strikes me in your post is that your AHI is ranging from 2 to 5. I think a reasonable ambition would be to see it range from close to 0 to 2. That could really make a difference in your daytime feelings of being rested.

If you are interested in pursuing this, could you do several things so the experts can help you?

* Download the Oscar software: https://www.sleepfiles.com/OSCAR/ Then import the data on the SD card that is (I hope) in your machine. And then organize and post a daily chart (more information above).

* Add your machine and mask information to your profile. That way it will be easy to access for anyone trying to offer help.

[realshelby]

One thing I have learned here, and much of that thanks to Pugsy, is to NOT worry about how someone else is doing on cpap. BMI? Many think being obese guarantees sleep apnea and a BMI under 25 means you should not have sleep apnea. If that is something that bothers you, don't worry about studies. You can find about any study to prove what you want proven, fact or not. I can tell you, to my surprise, that many on the forum here are far from obese yet still have serious sleep apnea. Does body weight have an effect? It does. But losing 100 pounds isn't likely to allow you to say your AHI scores are in the normal range without your cpap machine.
Your AHI could be improved. Will that make you feel refreshed and ready to tackle anything coming your way? Probably not so much. Can take time and getting your cpap therapy working and comfortable certainly takes some time. Because everyone is different. Download the "Oscar" program and learn to read it. There are those here on the forum that will give excellent advice on what changes they would make. Up to you to follow through, but most often the results are worth the time.
I expect many of us went through the "why the heck is this happening to me" period. But with time you realize it IS helping and in my case it helped a lot. Don't worry about why you have it. Just make it work as well as it can and you will realize it is a good thing after all.

[palerider]

AHI is typically between 2 to 5.

Well, that's too high, under 1.5 are better numbers, (an ahi of 5 means your sleep is interrupted, on average, every 12 minutes)

[ElusiveSleep]

The researchers' goal was to stratify CPAP compliance according to BMI. The primary factor associated with normal BMI, which differed from those obese, was that many of the normal subjects had a low arousal threshold.

What the researchers concluded was that since a large proportion of normal BMI subjects have low arousal threshold, perhaps this makes them more sensitive to various external stimuli (Sudden changes in pressures from APAP units, noise, bed partner jostling, etc), thus causing multiple micro-arousals or conscious waking.

I was really in a tough place for several weeks after starting the APAP with a pressure range from 4-14. Based on daily examination of OSCAR charts, I noticed long periods (several minutes) of pressure spikes at 14. Requested doc to lower max pressure to 11 which started this past Sunday. Feeling so much better, finally out of the the previous zombie trance. My AHI is now in range of 1-2, also leakage (which was often above 24L at 4-14) has been in an acceptable range.

Perhaps the steady pressure at 14 was causing many micro-arousals that have since lessened with new max pressure reset to 11.

I know several men who use CPAP and have no complaints, however all of them are big guys and their BMI is obviously in the obese range.

[Miss Emerita]

It's so good to hear things are going better! And I'm glad you're using Oscar. One question: do you consider raising your minimum a bit? Most people find themselves feeling a bit air-starved at 4. For many, a minimum of 6 or 7 is much more comfortable.

[ElusiveSleep]

Thanks for the suggestion, Mrs. E. After falling asleep, and before any events, pressure rides at ~6. For now, my goal is to arrive at the lowest maximal therapeutic pressure (~ 9 or 10). The sharp jumps to maximum pressure caused by junk flow rates are a sleep quality killer.