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Does mouth breathing invalidate my AHI score?

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sulamaye +0 points · about 1 year ago Original Poster

Hi,

I have started using a cpap (DreamStation phillips) in the last few months. I struggle with insomnia so it’s not an easy journey trying to get to sleep with so much noise and just the feeling of the mask. (I have tried 5 different nasal masks).

I use a snoreapp to record my sleep and sometimes i can hear that i am breathing out through my mouth. Not always but periodically. I have historically used a tiny bit of tape to keep my mouth shut (done it for years way before got diagnosed with sleep apnoea) i know people get freaked by the idea but it never killed me! However, i find with my aversion to having the mask on my face, head, nose etc (have no problem with the actual air pressure don’t find that hard at all) i am more likely to sleep better without the tape as it just reduces one bit of sensation on my face.

However, if i am mouth breathing at times does this mean the machine can’t accurately register and record my AHI or just that i am more likely to have More AHI if i mouth breathe which will be clocked by the machine?

My AHI is always under 5 whether i tape or don’t tape, mouth breathe or not. I just worry that if i don’t use tape and have intermittent mouth breathing i am getting more AHIs than the machine is able to tell me about.

Any thoughts?

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Sierra +0 points · about 1 year ago Sleep Patron

My wife and I both use a CPAP and I track the results with a freeware program called OSCAR. It lets you see when there are excessive leaks and displays them as grayed out areas on the data graphs. These are times when the leak rate goes above the 24 L/min red line (at least on our ResMed machines). My understanding is that the leaks from an open mouth tend to be flat topped in shape. I mouth tape and generally do not have leaks above the red line. My wife does not mouth tape, and does have more leaks, and some of which I suspect are mouth leaks. See the graph below. Some of the leak periods have flat tops and perhaps are mouth leaks, while one other is ramping up and perhaps is the mask not sealing on the face. She uses a Brevida nasal pillow mask. You will also see there are no events recorded during the grayed out high leak periods of time.

As far as the impact on AHI, large leaks above the red line on the ResMed (and I think DreamStation is similar) suppresses the reporting of apnea events. If it is a marginal event sometimes they can be reported as unidentified events. The high leak prevents the machine from determining what type it is. But in general events get suppressed during high leaks and as a result reduces the frequency of events and AHI. You could be still having them, but they are not reported. I agree with your thoughts that your machine is likely under reporting events during large leaks.

Hope that helps some,

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sulamaye +0 points · about 1 year ago Original Poster

Hi, thank you for that it’s very interesting. It hasn’t made sense to me that if i mouth tape i will likely get a slightly higher number of AHI episodes reported than if i don’t. Which does seem to indicate it is not picking them up as accurately, because I would presume that mouth breathing impairs the delivery of air pressure so AHI should rise not fall.

Is your wife not concerned that she is not adequately treating her condition?

Does that software work with any machine, how do you connect it?

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Sierra +0 points · about 1 year ago Sleep Patron

Actually unless the leak is very large, the machine is quite capable of keeping up with the leakage flow. If you look at the blue mask pressure graph you can see it is not affected by the leaks. The problem the machine has is that it does a rapid cycle of the air flow once an event is detected, and from that it also looks at what impact that has on pressure. If it is an obstructive event then a flow cycle causes a larger pressure cycle. With an open airway or central event it does not impact pressure much at all. That is how the machine distinguishes between an obstructive event and an open airway event. Then it decides based on the type of event whether or not to increase pressure in response to the event. With an obstructive event it increase pressure to open the airway. When the airway is already open then it is of no value to increase the pressure. And since increased pressure can cause more frequent open airway events, it is actually counter productive to increase pressure. When the leakage is high, the machine apparently cannot detect the impact of flow on pressure so it simply ignores them. So you may be having events during a high leakage event, but you will not know about it. The solution of course is to solve the high leakage cause. . She tried mouth taping for a while, but does not like it. She told me that women are smart enough to learn to keep their mouth closed... I am smart enough to not contest that one! I do remind her when she is having significant events and sometimes she makes improvements by adjusting her mask. Overall her long term average of AHI is less than 0.5, so I don't think it is having a significant impact to her overall AHI. My AHI is about 0.8 and higher so I am in no position to tell her that she has to improve!

OSCAR works with ResMed machines that have an SD card, and also I believe the DreamStation and DreamStation 2. It may not work with some very basic CPAP machines that do not have auto mode or even a SD card slot. To use it, you need a PC or Mac, and a SD card reader to transfer the data from the card to your computer. And of course you need the SD card in the machine. Some clinics pull a bit of a dirty trick and remove the SD card so the machine does not capture data. I have no idea why, because when you don't capture the data on a SD card the data is lost permanently. If there is no card, then any SD card less than 32 GB should work.

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sulamaye +0 points · about 1 year ago Original Poster

Thank you so much for all that detailed information, it is really helpful.

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Roland123 +0 points · about 1 year ago

I recommend you go further after consulting a doctor. It is the best way!

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sulamaye +0 points · about 1 year ago Original Poster

I don’t understand what you mean, go further in which direction?

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