Leakage vs. AHI

[jeffy1958]

I've been mulling this over for several days on whether to post or not to post. Not wanting to pass out any un-useful information and get anyone in any kind of trouble. You need to check/discuss with your personal physician on "ALL" matters regarding your therapy/treatment. So let me start with the "disclaimer" and say: I am not affiliated in any way shape or form with any medical profession, nor am I any kind of expert when it comes to CPAP and the treatment/therapy of said affliction. I'm just a lowly industrial mechanic - period.

I recently had an appointment with my E.N.T. Specialist and in a nut shell she explained that as long as the AHI was low (mine is and has been 0.6) there is no cause for concern about the high leak rate. We talked about mask fitting and she explained we do not know what we do or what is going on when we sleep. We can start out the night with no leaks and during those hours we can do many things to knock the mask out of position. So much for the "Perfect Mask Fit" article I wrote!!! I walked away feeling... No mater what I do, or how hard I work, I will never get it right, I will always leak. And this from someone who has the tendency of being meticulously perfect in every endeavor I undertake.

This in no way has or will discourage me from my treatment/therapy. It's made me realize there is only one true indication that my therapy/treatment is working: HOW DO I FEEL IN THE MORNING. And that is not on any "printout" I've ever seen. I've been on CPAP since Oct. 2010 and I'm here to tell you sleeping without it is miserable to say the very least.

In closing: for you "rookies" stay with it - do not give up - do not be discouraged by what you may see regarding your data. And for the rest of us "oldies" as useful all that data is; it can be a big let down in some ways. As hard as it is for me not to check, I try not to look and use the "How Do I Feel" gauge.

....and ALWAY - ALWAYS - ALWAYS consult with your physician!!!

P.S.
On a positive note, she will be using my article to assist her patients so maybe I'm doing something right or at least on the right path.

And did I mention that you should always consult with your physician???

[Peter_C]

I'll jump in and bite. I've been playing the numbers game recently for the last 5 months or so, and spent $$$ trying to get my leak rate under control.

THe problem with your Doc's thinking is, at some point, when the leak rate gets high enough, you can't get the right pressure, and the machine can't figure out as accurately what is going on - am talking big leaks all night, not random little spikes.

My AHI historically has been around '10' on good days, worse from there - but without my dream machine I am one of those 90+ AHI people. So I too love and need my dream machine.

I have found, that *if* I got to a FFM (which I hate), and strap it down tight, I honestly can get a consistent low leak rate, and my AHI has gone down to as low as 2-3, AND, I have seen my pressure vary during the night (rather than just staying up high all night).

I will agree completely with you that it simply comes down to how do you feel in the morning~! Number chasing (to a point) is just a game. But, your AHI and all other reading will be suspect unless you can keep your leak rate below the magic line (I think 24Lpm??) - gesh, I always go brain-dead on that number.

I've been back on my 'Wisp" (favorite mask), and raised both my min EPAP and PS by '1', as a 'cushion' - and my AHI is bouncing from 6-14 currently, and my leak rate is poor (mouth hissing) - but I am feeling great in the morning, and do not wake at all during the night due to mask events. And so I am trying to decide myself - stick with comfort and how I feel, or strap on, quit whining, and chase my leak rate and have mask events every single night...

[jeffy1958]

Peter;

THe problem with your Doc's thinking is, at some point, when the leak rate gets high enough, you can't get the right pressure, and the machine can't figure out as accurately what is going on - am talking big leaks all night, not random little spikes.

We did talk about when the leak becomes high enough as to not get the right pressure. But that doesn't seem to be an issue, so far, with me. A 4 gig card can hold much data and I went back as far as I could, sending her that info and she still thinks it's not a big issue.

[PaytonA]

I think that the importance of the leak rate may depend on what its magnitude and duration are. It seems to be a fact that with leak rates beyond a certain threshold the machine begins to have trouble sensing the events that it is trying to prevent. When this is the case, I think it is a big deal. I am not trying to take anything away from your doctor. I have worked with a lot of doctors and have found that many of them (with major exceptions like DocWills) tend to be a little lost when it comes to how equipment works. If one is sleeping well and feeling good and has good oxygenation then maybe the leak rate is not a concern.

I also think that "How I feel in the morning" is very subjective and is not black and white but a lot of shades of gray. Personally, I am kind of chasing the feeling that I had for about a 2 week period over a year ago. I was using a nasal mask and was not checking my data. I since found that I had major mouth leakage even with a chin strap and have changed to a full face mask. I felt so great for those 2 weeks Woke up feeling well rested. I had great energy all day and slept great. Currently, I wake up feeling rested but I get a little drowsy sometimes during the day and I am still sleeping well. It is just not as good as what it was.

My thought is that how you feel is important but the AHI data may be skewed by the leak rate.

Best Regards,

PaytonA

[zonk]

I recently had an appointment with my E.N.T. Specialist and in a nut shell she explained that as long as the AHI was low (mine is and has been 0.6) there is no cause for concern about the high leak rate.

Is she right or isn't she right ... depend on her definition of high leak rate
During high leak rate, the machine cannot keep up and nor the data is reliable

Leak graph should gives you an indication whether unintentional leak is good or bad. According to ResMed, unintentional leak below 24 l/m is acceptable (lower is better) but not the end of the world if goes above the threshold line for a brief period, might be a chinstrap (worn over the mask) is all that required to keep mouth closed and the mask in place for the active sleeper

IMO ... AHI numbers are meaningless in the presence of high leak rate numbers
Any leak large or small, disturb your sleep is a concern needed to sorted it out prior of making any sense of AHI numbers

[SleepWrangler]

I recently had an appointment with my E.N.T. Specialist and in a nut shell she explained that as long as the AHI was low (mine is and has been 0.6) there is no cause for concern about the high leak rate.

While this may be true I find my heart rate accelerates sometimes with measurable SpO2 desaturation events whenever I mouth breath. On the PAP machine this shows as a leak sometimes with corresponding apnea events and sometimes not. On my worst night AHI<0.64.

Your E.N.T. Specialist knows your medical history and can help guide your treatment. By that I mean you individually. I don't think the statement about "no cause for concern" translates into general advice for "rookies". Sure it's unhealthy to obsess over metrics simply because they exist but instead you ought to work with a health professional to interpret their meaning.

[diamaunt]

But, your AHI and all other reading will be suspect unless you can keep your leak rate below the magic line (I think 24Lpm??) - gesh, I always go brain-dead on that number.

according to the resmed autoset manual, the max flow it can handle at 20cmh2o is 136lpm. at 12cmh2o, it says it's good for 164lpm.

seems that there should be plenty of breathing room over that 24lpm.

[PaytonA]

But, your AHI and all other reading will be suspect unless you can keep your leak rate below the magic line (I think 24Lpm??) - gesh, I always go brain-dead on that number.

according to the resmed autoset manual, the max flow it can handle at 20cmh2o is 136lpm. at 12cmh2o, it says it's good for 164lpm.

seems that there should be plenty of breathing room over that 24lpm.

The 24 lpm is over and above the vent rate which if memory serves is 20-50 lpm. The real problem however is not the ability to supply the air but its ability, with incrreased air flow to sense the thinfgs that it responds to and to sense the apneic events.

Best Regards,

PaytonA

[Moriarty]

The 24 lpm is over and above the vent rate which if memory serves is 20-50 lpm. The real problem however is not the ability to supply the air but its ability, with incrreased air flow to sense the thinfgs that it responds to and to sense the apneic events

I think that is the most important technical point to take away from this thread....

On the other hand - it is also not important to get bent out of shape over a stray 5 or 10 lpm of leakage if one is sleeping well and waking refreshed.

Cheers

David

[PaytonA]

On the other hand - it is also not important to get bent out of shape over a stray 5 or 10 lpm of leakage if one is sleeping well and waking refreshed.

Cheers

David

Agree totally