leak vs max leak vs 90% leak vs large leak

Can someone explain to me these different terms? I had my first large leak last night and I figure that is a real leak, like the mask coming off or something (which it had and the blower woke me up).

But in trying to understand my leak rate I am just not sure which of all these numbers are most important. I do know to subtract my masks intentional leak rate from the reported leak but just trying to fine tune all this is making me confused.

I do not think those titles and numbers are very meaningful nor useful. If you are keeping one days data only, as I did for last night, my leak was most of the time at 11, a few dips to 4, and few ups to 18. I actually looked in the database to find it, But the reported numbers on the right side of that trend graph: Avg Max =28, Avg 90%=18, Avg=11. I think the sw simply estimated the avg max based on some formula. It never exceeded 18, but it got that 28 number.

crossfit wrote:Can someone explain to me these different terms? I had my first large leak last night and I figure that is a real leak, like the mask coming off or something (which it had and the blower woke me up).

But in trying to understand my leak rate I am just not sure which of all these numbers are most important. I do know to subtract my masks intentional leak rate from the reported leak but just trying to fine tune all this is making me confused.

In a perfect world, the masks wouldn't leak. Yes, large leaks means the system is NOT working due to leaks. The best thing for you is to look at the shape of your leak line over the night and compare it with the expected leak for your mask at that pressure. Respironics compensates for some leaks such as small leaks from the mask. Leaks from your mouth cannot be compensated by the machine, so you lose therapy very quickly. I think leaks from nasal pillows are also not compensated well as the leaks can be quite significant compared with the intended flow.

Here is an example that I posted previously and you can see the difference in the shape of the leak line to use for comparison:

viewtopic.php?t=33270&highlight=

crossfit wrote:Can someone explain to me these different terms? I had my first large leak last night and I figure that is a real leak, like the mask coming off or something (which it had and the blower woke me up).

But in trying to understand my leak rate I am just not sure which of all these numbers are most important. I do know to subtract my masks intentional leak rate from the reported leak but just trying to fine tune all this is making me confused.

leak is the flow - the blue graph on encore pro

max leak is the largest flow there was while the machine was on - if you had a time when you took the mask off before turning off the machine say for a pit stop or if you adjusted the mask, then that will show up in the max leak even if it was only for a few seconds - that may not trigger a change in the graph on encore pro even though the leak occurred because of the resolution of the screen to the data encore graphs

large leak I believe is then the leak is over 75 l/min - on encore you may see a large black bar on the leak graph - if the large leak is short or several short ones you might not see the bar but you might still have a large leak - if you have an extended large leak, you will see the bar

take your mask flow rate for the pressure you are using and draw a horizontal line across the leak graph on encore - look and see how much time you are quite a bit above it - look for lots of spikes and plateaus above it - if you are spending a lot of the time more than x % (I use 20, others use 10 or 30) then you got problems - if your pressure is not fixed, then be aware that your leak (flow) will change as the pressure changes - that may or may not show up on the leak graphs as the leak graphs resolutions are not every unit

nothing with encore pro (or encore viewer either then) is super accurate mathematically - their programmers wouldn't know good math and sensitivity analysis if they saw it - remember it is just a crude estimate

the LED information on the m series also lacks I understand but I have no direct knowledge of it as I use a tank - you can be within x % on the leak information and still have leak problems - the graphs are a better than just one number

So, what I have been trying to do is look at the max and compare it to the max pressure and the leak rate for my mask at that pressure. Then I do the same at average and at 90%. Doing this I seem to be at around 2 for a leak at most and often below. Last night I had my first large leak and I think it was either mouth breathing or a time I woke and felt the mask completely away from my face. Or both were leaks but only one was the large leak.

I have been trying to figure this all out because on auto with aflex, I don't have a constant pressure and thus its harder to figure out the right leak amount.

I am using pillows. I may end up getting another mask, maybe the one here that is the current champion because so many people have it and can advise me. The pillows are nice in that not much is on my face but they move a lot when I move and I often wake up worried that it is leaking whether or not it actually is.

if you are just looking at max vs max, ave vs ave, etc. you are playing the fruit salad game comparing apples and apricots

if you can do a screen capture (alt & print screen at the same time), put that into paint for example, save that as a jpg, you can upload that picture to say photobucket and post the link or the image here and ppl can comment on your graphs - make sure you get both the pressure graph and leak graphs in the shot

well that is what I thought and why I was asking what the various terms mean. I will do a screen shot tomorrow and post it.

I missed describing the 90 % above - it is what you were at or below 90 % of the time - the 90th percentile value

Thanks Jules. I appreciate it.