AHI reading and Mask Fit

[Alcea]

My question is about the relationship between AHI and Mask fit. I had always thought that they were related, that if you had a 100% Mask Fit, you would have low AHI. But that has NOT been my experience The following occurs only when I use a Full Face Mask lying on my BACK. It never occurs when I use the Full Face on my side, and it never occurs when I use a nasal mask on my side or my back. For example in a given 6 day period, I had 3 nights with a mask fit of 100% (perfect) and an AHI of over 30 (terrible) and then I had 3 nights of a mask fit of 87 (not bad), and I had an AHI of 10-12 (not so bad). And, then I have had a couple of times where I had a Mask Fit of 14% and an AHI of 1.4. (How does that happen?) I have had this experience both when the pressure was set at a given number and when it was on auto.

What is the explanation of this? Is it 1) because the readings are inexact and not a true reflection of what is happening 2) The force of gravity is too strong and the pressure the machine is providing just can't overcome it. 3) Other factors I don't know about. This really puzzles me, and I hope someone can explain this.

[englandsf]

Can you co plate your profile and tell us which masks you're using.

It sounds like you may be mouth breathing with a nasal pillow mask. The mouth breathing may not impact your leaks but it will decimate your AHI.

Tell us more...

[ChicagoGranny]

I hope someone can explain this.

Join the forum, go to User Control Panel, fill out your equipment profile and post again in this thread.

an AHI of over 30

You badly need to get involved in the forum and let members help you figure out the problem and get a good therapy.

AHI of 10-12 (not so bad)

Yes, that is bad. You can do much better if you get involved in the forum and let members help you.

Hope to see you back here,

[OkyDoky]

My question is about the relationship between AHI and Mask fit. I had always thought that they were related, that if you had a 100% Mask Fit, you would have low AHI. But that has NOT been my experience The following occurs only when I use a Full Face Mask lying on my BACK. It never occurs when I use the Full Face on my side, and it never occurs when I use a nasal mask on my side or my back. For example in a given 6 day period, I had 3 nights with a mask fit of 100% (perfect) and an AHI of over 30 (terrible) and then I had 3 nights of a mask fit of 87 (not bad), and I had an AHI of 10-12 (not so bad). And, then I have had a couple of times where I had a Mask Fit of 14% and an AHI of 1.4. (How does that happen?) I have had this experience both when the pressure was set at a given number and when it was on auto.

What is the explanation of this? Is it 1) because the readings are inexact and not a true reflection of what is happening 2) The force of gravity is too strong and the pressure the machine is providing just can't overcome it. 3) Other factors I don't know about. This really puzzles me, and I hope someone can explain this.

Mask fit, while necessary for the machine to provide the pressure necessary to prevent apnea, will not by itself prevent the apneas. It is the correct pressures that prevent the apneas. Also when you have lots of leaks the machine may not be able to interpret your events and record them.
We would be happy to help you but we do need more info and it takes some learning on your part to take control of your therapy.
Start by registering and entering your equipment. This might help you do that. wiki/index.php/Registering_Equipment_in_User_Profile
Once we know your machine we can guide you to your clinical manual and software to help you take control.

[Alcea]

The point is that the mask fit was 100% and the pressure was right. I tried it with the set pressure and then with the auto pressure. I understand auto pressure can accentuate the leaks, but in these cases there were no leaks and still I had AHI of 30. There is another piece of this that I don't know about. Or maybe noone knows. Systems don't always work perfectly. Maybe that's the closest I can come to an answer.

[OkyDoky]

The point is that the mask fit was 100% and the pressure was right. I tried it with the set pressure and then with the auto pressure. I understand auto pressure can accentuate the leaks, but in these cases there were no leaks and still I had AHI of 30. There is another piece of this that I don't know about. Or maybe noone knows. Systems don't always work perfectly. Maybe that's the closest I can come to an answer.

If there were no leaks and your AHI was 30 the pressure is not controlling them. What do you mean by the pressure was right? As in doctor ordered? Take a look at your data with Sleepyhead if you have a data capable machine. The AHI doesn't tell us the breakdown of obstructives, hypopneas, and centrals, which is also important because if centrals are a factor increasing pressures will not help and may cause increases.
Let us know your machine and we can go from there.

[Alcea]

My machine is a Respironics 560P/REMstar Auto A-Flex C Pap with a humidifier. For example, during the three nights with the AHI of 30, the Central Apneas averaged 11. I have never read anything about central apneas and would like to know more. The settings - done by the doctor - for the auto setting were Min 7.0cmH2O and Max 18.0cmH20. I tried this for six days. The fixed setting was -cmH20 ( I don't understand this). Is position a piece of this? This high AHI ONLY occurs when I am on my back with a Full Face. If I sleep on my side, I get pains in my arms; the nasal masks, which always give a perfect fit on my side or my back and a perfect AHI either dry out my nose (the new Dreamwear) or leave serious red marks, which I assume is not good over time.

[Cardsfan]

CmH2O stands for Centimeter of water. It is a unit of measurement of pressure in cpap machines.

When you had the pressure set at a fixed number, what was it set at?

Edit your profile to include your equipment, makes it easier for us to help you.

[OkyDoky]

My machine is a Respironics 560P/REMstar Auto A-Flex C Pap with a humidifier. For example, during the three nights with the AHI of 30, the Central Apneas averaged 11. I have never read anything about central apneas and would like to know more. The settings - done by the doctor - for the auto setting were Min 7.0cmH2O and Max 18.0cmH20. I tried this for six days. The fixed setting was -cmH20 ( I don't understand this). Is position a piece of this? This high AHI ONLY occurs when I am on my back with a Full Face. If I sleep on my side, I get pains in my arms; the nasal masks, which always give a perfect fit on my side or my back and a perfect AHI either dry out my nose (the new Dreamwear) or leave serious red marks, which I assume is not good over time.

Great you have a data capable machine so you can get the software and see what is happening. Do you have a copy of your Sleep study results? I wondered if you had centrals during your study. Obstructives, Hypopneas and Flow Limitations are all different degrees of obstructing the air flow. True Centrals are from the brain not telling us to breath and the machine doesn't address those because it checks and finds out your airway is open so increased pressure doesn't help. Now you saw I said True centrals because there maybe some readings that show as we are transitioning to sleep and waking up that we all do. Such as holding our breath while turning and these we call sleep/wake/junk and count them out. That's why looking at the graphs that Sleepyhead gives is helpful.
Your machine has an Auto mode which I take it was set initally at 7 cm/H2o minimum and 18 cm/H2o but I'm not sure if you still have it set this way.
The other mode it has is CPAP mode which is only one single pressure so when you changed the settings what did you do?

Most people have higher AHI's when they are on their back because of the relaxation of the tongue more to the back of the throat. That is how the APAP mode is helpful because you may need lower pressures if you sleep on your side or stomach but then when you turn to your back they can increase the pressure to cover the increased need.

As far as the masks issues with the nasal masks you may be breathing out of your mouth while asleep and if the leak is large enough or long enough the machine may not record all of your events. With the full face for comfort there are liners such as http://padacheek.com/
Now here is a link to get the clinical manual for your machine. Scroll down to section Three and follow their directions to have them email it to you. Choose Respironics PR System One 60 Series REMstar Auto with A-flex .

This site tells you how to download Sleepyhead. https://sleep.tnet.com/resources/sleepyhead and read the information from your SD card.
Once you have that done. We can tell you how to post here so we can look at your data.

I know there is a lot to learn, just take it a step at a time and keep using your machine.

[palerider]

My question is about the relationship between AHI and Mask fit. I had always thought that they were related, that if you had a 100% Mask Fit, you would have low AHI. But that has NOT been my experience...

What is the explanation of this? Is it 1) because the readings are inexact and not a true reflection of what is happening 2) The force of gravity is too strong and the pressure the machine is providing just can't overcome it. 3) Other factors I don't know about. This really puzzles me, and I hope someone can explain this.

well, that's because mask fit and ahi have nothing to do with each other, your previous theory is 100% wrong.

AHI has to do with sleeping position, where in the sleep cycle you are, what kind of mask you're wearing.

'mask fit' has to do with how much your mask leaks, which, unless it's leaking horribly, has nothing to do with AHI.

[ChicagoGranny]

Edit your profile to include your equipment, makes it easier for us to help you.

And easier for Alcea to get help.