What's the difference between HI and AHI?

[Alsacienne]

I'm still trying to lower my AHI level. I'm doing so by changing things very slowly and giving the change time to show a trend, so not looking for a one night wonder!!

Last night I increased my pressure setting. My HI count was substantially less - down from 1.3 typical to 0.3 (is this cause for celebration or just a blip?!!!) but my AHI rate remained 'normal' (for me) at 6.8.

I'll be watching the changes for a good week or so before raising the pressure again. Is there a correlation between HI and AHI and what do I do to decrease them both other than raise my pressure - and try to minimise those infernal leaks?

[LSAT]

AHI is the total of AI + HI....If your HI is .3 and your AHI is 6.8, that means that your AI is 6.5. Apneas that high means that something needs adjusting. Your mask or your pressure. Go to the top of this page and click on the CPAP WIKI Lightbulb for definitions of CPAP terms.

[Alsacienne]

Thanks! Wish I'd seen the lightbulb first, but we hopefully all get there in the end!!

I know the mask isn't the problem, and it's a bit more subtle as in France, satisfactory treatment is said to be less than 10 events per hour, whereas in the UK and the US it's less than 5. My doc and sleep tech are not concerned by my results but I am, and I definitely want to decrease my thickheadedness on waking!

So if my mask is fine, leaks are just ok being under 0.4, what if the gradual increase in pressure doesn't lower my AHIs?

[Bobby269]

Even if every thing is going correctly, it takes time for your body to feel safe. For me it took 3 months to get below 10.

[DaveMunson]

You raise your pressure until you minimize the hypopnea's and apnea's. The sleep study is suppose to tell what that pressure is. Seems like, most times, the sleep study pressure is not perfect.

Apnea's are total blockages and hypopnea's are partial blockages.

I believe, for most, as you increase your pressure the Apnea's stop first than the hypopnea's stop, than Snoring stops. At least that's the way it worked for me.

Also, as pressure goes up, leaks increase and other difficulties arise.

You can minimize AI's, HI's, snoring by increasing pressure, minimizing leaks with pressure that would normally work and stop mouth breathing. You may need more or less pressure for different seasons, your how exhausted you are, fitness, et. al.

The best way is to set your pressure to the minimum that works. This is why we all work on leaks and mouth breathing and everything else rather than just blasting away at max pressure. There are other reasons why not to just keep increasing pressure.

[LinkC]

Making a change and then waiting a week is a good call. If you chase the numbers on a daily basis, no telling where you will end up.

Also, higher presssures can result in central apneas, disturbed sleep and aerophagia, etc. So you want to try for the minimum effective pressure. It's a compromise...

[Alsacienne]

Thanks again for continuing information. Just to say that I'm already having problems with 'gas' (!!) My sleep study showed a minimum of 12.8 so my CPAP was set at 13, but this was still giving me 8 or so AHIs plus occasional leakage ...

My sleep tech put it up to 14 but this has not improved matters, so I've put it up to 14.6 ...

I originally started at 16 and was never told why it got reduced to 12 .... so perhaps a gradual ascent will bring the AHIs down without stirring up too much other stuff. Obviously the nearer I get to 16, if things don't start to improve I'll chat with my sleep doc ... I'm on annual appointments with the next one due in December.

More advice and information always welcome, and much appreciated.

[GumbyCT]

It should also be noted that when you have leaks, the pressure the machine is putting out will be a lower pressure at your your airway (because of the leaks). Plus the machine will sense fewer events because of the leaks. This is why when discussing AHI, pressures, etc. the mask make/model (even the size) and leak rate are important details.

[DaveMunson]

Yea. Gas is one of those things.

If your pressure is 16 and you have leaks (when it matters in the middle of the night) or mouth leaks, your effective pressure may be only 10 and that is not enough to keep you from having apnea's & hypopneas.

Finding out what works like this is why so many of us recommend an auto machine. Leaks, changes in fitness, well-being, mood, exhaustion, weather, will also change the pressure needs of your body. It takes time to learn to adjust for all of these things but it can be and is done.