What is the relationship betwen mask leaks and AHI?

Can anyone tell me if there is a relationship between mask leaks and the AHI rate? My AHI rate will one day be 3.5 and the next night it will be 7.9 and I don't understand why. I don't necessarily feel like my mask leaks any more or less any one nigh t over the next but yet the variance exists in my AHI. If there's some way to improve my AHI or at least reduce it and keep it consistent, I'd like to know.

If you're losing air through your open mouth when asleep (and that will register as a leak) then your AHI will be higher of course, so think about trying a full face mask rather than a nasal one, or at least try taping for a couple of nights to see if it helps... you may be moving around a lot and dislodging the mask too, so possibly a mask that fits better or is adjusted better will help.

Your AHI will be lower if there are no leaks. Leaks will show up as higher AI and AHI. Leaks can be from a mask or from mouth breathing. You could be breathing through your nose and exhaling through your mouth. If you think you are mouth breathing you could try a chin strap and or mouth taping...or...a Full Face Mask .

OK, Thanks. I have a chin strap that I wear to keep my mouth closed when I'm wearing my mask. Someone else told me that the straps won't stop you from breating out your mouth so you're right a full face mask might still be the ticket. But is it the leak itself that allows the apnea to occur or is it just the fact that the presure isn't right?

moondoggy wrote:… is it the leak itself that allows the apnea to occur or is it just the fact that the presure isn't right?

I've wondered about this too:

1) Does the leak - loss of air pressure - actually allow an apnea - an airway obstruction - to occur? or

2) Does the leak just cause the machine to give a false report of an apnea where no obstruction really occurred?

Nate

Leaks and apneas each occur for different reasons, but leaks are about how well set up you are when on Cpap, apneas occur regardless of whether you're on Cpap or anything else - no connection to external happenings - they are neurological or obstructive and never occur because of leaks.

Try it...close your mouth tightly and see if you can blow out through you lips. I don't have a bit of trouble doing it and my air from my CPAP machine was blowing out the same way. I don't open my mouth often at night and not to breathe but I do open it so I had to find a way to close it. See my post on covering my mouth with my chin strap.

Leaks don't "cause" apneas, but they do allow them. A leak can effectively reduce the CPAP therapeutic pressure below an effective level, and apneas occur.

I can't think of a scenario where the machine would score a leak as a false apnea.

I too think that if you have a significant leak your air pressure will be adversely affected, therefore compromising your therapy. If your pressure is not where it should be, apnea could be a result of that. I noticed that if my mask straps aren't "right", which happened to me last week,I subsequently got leaks and my apnea index went up. I figured out that it was my straps, adjusted them, got a good fit and my apneas went back down to my average.

So, do any of you know how to go about reducing your AHI level? I was thinking that if it was something to do with leaks but if leaks don't have a specific relationship with AHI then I'm at a loss to determine how to get my AHI down. Any ideas?

What software are you using for your reports or are you getting the AHI information off the LCD screen?
What is the AHI breakdown for the categories of events for the night with the AHI of 3 something and the AHI of 7 something?
How much is central index?
How much is Obstructive apnea index?
How much is Hyponea index?

Need to figure out what you are seeing before we offer ideas on what to do.
Are you seeing centrals???

moondoggy wrote:So, do any of you know how to go about reducing your AHI level? I was thinking that if it was something to do with leaks but if leaks don't have a specific relationship with AHI then I'm at a loss to determine how to get my AHI down. Any ideas?

You need to monitor your therapy with software. Leaks can and do allow events to increase so they are in fact related.

Your therapy is only effective when your leak line (as seen in the software) is a flat straight line (min. peaks & valleys) IF leaks are to high, your machine will NOT sense events and give a low AHI. Therefore, you can see an increase in AHI when your leaks are under control but your pressure is NOT sufficient to suppress events. You can leak excessively and not be aware of it.

There is an allowable leak for each mask that varies with the pressure. This leak is to wash out CO2 buildup. Each mask manufacturer publishes the spec for the mask and that chart is included in the mask package when new. You can find this info by searching online also but again it varies by the mask AND the pressure.

You should not use the LCD readout from the machine for an indication of no leak as that readout is notoriously inaccurate. Again, You can leak excessively and not be aware of it.

To summarize - your data is only accurate when your leak line is flat and within the manufacturers specs. Your AHI only has meaning when you also provide the mask make/model , pressure, AND leak data.

Other than that the AHI is meaningless, to me. When AHI <5 therapy is considered to be effective BUT you should also consider how you are feeling. Keeping a hand written notebook with your daily notes and numbers is a good way to track your therapy. Use it to write down questions you might have as you think of them , BEFORE they perish due to the Brain Fog.

HTH,
Good Luck