AHI Inconsistency

[HairPower]

I have been on CPAP therapy for 4 months now and am generally happy with my progress. I do however, have a question that has puzzled me. 
A good AHI under 5 seems to be the benchmark that we are all aiming for and while I generally achieve this every night, my AHI is very inconsistent. Example for 7 past nights - 3.5, 1.5, 5.2, 1.8, .2, .5 and 4.8.
All 7 nights were similar - around 7.5 hours sleep, acceptable leakage with machine settings fine tuned to suit me.
What causes these fluctuations in AHI? Is my machine handling and rectifying obstructive events or do some fail to get resolved by the CPAP machine? Why the inconsistency?
Many thanks.

[Walla Walla]

Without seeing a chart I'd guess your getting clusters of obstructive events from time to time. A soft cervical collar can help prevent that.

[sheepless]

what walla walla said. and,

I fear I'm stating the obvious but: in short, assuming no variation in machine settings, you are the primary variable. & your surroundings. what and when you eat & drink, mood, emotional state, how you feel, bladder, muscle cramps, itches, restless legs, periodic leg movements, differences in mental state, happy, stressed, worried, etc., - nothing new here. also temperature, humidity, noise, light, etc . etc. all the things you'd expect to affect sleep quality.

[Sleeprider]

For many people, inconsistency is the only consistent thing about therapy. You seem to be using 16-20 pressure with EPR at 3, and hopefully you are finding that comfortable and effective. If not, the next step for you is bilevel where we can affect pressure support, inspiration timing and trigger/cycle sensitivity. If not for the data, would you judge your results as comfortable?

[sheepless]

following up on sleeprider's comment, how you feel is paramount. I think it's safe to say that I have mixed apnea. I had some higher ahi's than the one's you reported but the 2 main negative characteristics of my experience with apap were inconsistent results and after 1.5 years I still felt awful.

[CB91710]

Without seeing a chart I'd guess your getting clusters of obstructive events from time to time. A soft cervical collar can help prevent that.

Or what most often impacts my consistency (though not to the degree of yours, I'm generally floating between 0.0 and 1.0) are CA events... which may or may not be legitimate CA's as they tend to occur around the time that I am in transition... often in the morning when I am in that state of "Should I get up or catch another half hour?"

What is important...  How do you feel?  Are the symptoms that guided you into having a sleep study done being alleviated?
For me, it wasn't "fog" so much as it was extremely loud snoring, and falling asleep when driving.

[HairPower]

Wow sheepless, when you put it like that I didn’t realise what a huge “primary variable” I am.  ?  Nevertheless, I feel a lot better than I did before therapy and am grateful for it.

[HairPower]

Thanks Sleeprider.  I do feel much better than I did pre therapy regardless of the inconsistent AHI readings.  Most of this was due to yours and other forum members’ advice  on machine settings, etc which has been greatly appreciated.  I guess as long as I’m feeling good, my natural competitiveness of going for a lower AHI every night should be ignored.

[tedvpap]

Large variability means your treatment is not robust. This is often due to the lower pressure being set too low. A common mistake.

[HairPower]

Thanks Rich, my symptoms of day tiredness, snoring and stopping breathing during sleep have thankfully been eliminated so I have nothing really to complain about. By the way, falling asleep while driving is not a good symptom to have. You certainly need to eliminate that.