Good data but bad sleep?

Country4ever · Post by **Country4ever** » Sun Dec 02, 2007 9:19 am

Where can I get info about which mask allows for how much leak, and what it all means?

ozij · Post by **ozij** » Sun Dec 02, 2007 9:55 am

Masks for cpap use have vents.

When the machine blows air into your airway, some of the air also gets blown out the vents - even when you inhale.
The constant, stable leak, cause by the vents in the mask and measured by the more sophisticated machines is the masks intentional vent flow rate, or intentional leak.
When the pressure is higher, the amount of air coming out of the vents is also higher.
Each mask has its own intentional flow rate - you will find a graph or table of the change as the pressure rises on the mask's manual.

Forum member dsm generously created a table of the data sent to him from other members. and published it on his site at: http://www.internetage.com/cpapinfo/leak-rates-1.html

When you want to know how bad (or good) your leak rate is, you have to check the reported leak rate against the built in (intentional) leak rate.

O.

Country4ever · Post by **Country4ever** » Sun Dec 02, 2007 11:05 am

Thanks Oz.
I don't believe I got a booklet with my mask, but I'll check again.
In another post, someone mentioned that the leak rate on either my machine or the swift nasal pillows is given in l/sec. I'm trying to figure out how that translates into anything I can understand. When I look at that table you provided a link for, I'm not sure what it says. For example, if I go by the Swift pillows at a pressure of 8, it says "29". Is that the same as ".29"? Sorry I'm so slow with this.

lking · Post by **lking** » Sun Dec 02, 2007 11:55 am

I use an OptiLife mask. Until 3 days ago I used an M Series PRO CPAP that indicated the 7 day average leak rate was 1.9. My sleep specialist switched me to a BiPAP machine so for the last 3 nights I have been using my new M Series BiPAP Auto w/Bi-Flex. This machine shows my leak rate as 30.6 L/min. The graph on my mask indicates that the intentional leak rate at my titrated pressure of 13 is about 31 or 32 (hard to tell exactly on the graph).

I don't know how to interpret the varying information. Do these 2 different machines use two different types of readings for the leak information or do I have a huge leak?

jules · Post by **jules** » Sun Dec 02, 2007 12:21 pm

No the LED .29 is not the same as 29 flow rate for the mask.

This is the manual for the Swift. On page 11 there is a graph of mask flow rates. The 29 for a pressure of 8 can be obtained from that. Notice that the chart indicates a large possible error. +/- 6

http://tinyurl.com/376l4c

The mask flow rates in that chart are in liters/minute. So in order to compare what you get on your LED with that, you have to convert. The number on your LED is the excess over the built in mask leak rate in liters/second. So that is where I came up with the formula for using a pressure of 8.

In the Resmed menu there is a choice of mask types. Look at page 27 of the Vantage maual - link below.

http://tinyurl.com/3aaepn

Once you know the mask type, the pressure, and the LED EXCESS leak rate you can determine approximated what your leak is and see how far off you are from the expected rate. I feel anything over about 30 % off needs to be examined and of course the more you are off target the more you need to figure out why. As I said last night there might be reasons for the leaks but again without a graph of the leaks during the night, it is hard to know why. Dislodging the mask during the night is pretty common and you might try to work on that first. Also if you take the mask off accidentally or go to the bathroom during the night and don't turn off the machine first, that will cause leaks. Your leaks are not alarming.

You might want to look at swift fixes and see if one of them will help decrease your leaks. These are the two threads I refer people to but there are others.

viewtopic.php?t=5965&highlight=swift+fix

viewtopic.php?t=14991&highlight=swift

ozij · Post by **ozij** » Sun Dec 02, 2007 12:29 pm

Leaks are reported either in liters per second, or in liters per minute.

Check the info on your machine to see what it reports on the LCD.

To conver a "liter per second" number into a "liter per minute" you have to multiply by 60.

To conver L/m (liter per minute) to L/s (liter per second) you have to divide by 60.

O.

jules · Post by **jules** » Sun Dec 02, 2007 12:33 pm

lking wrote:I use an OptiLife mask. Until 3 days ago I used an M Series PRO CPAP that indicated the 7 day average leak rate was 1.9. My sleep specialist switched me to a BiPAP machine so for the last 3 nights I have been using my new M Series BiPAP Auto w/Bi-Flex. This machine shows my leak rate as 30.6 L/min. The graph on my mask indicates that the intentional leak rate at my titrated pressure of 13 is about 31 or 32 (hard to tell exactly on the graph).

I don't know how to interpret the varying information. Do these 2 different machines use two different types of readings for the leak information or do I have a huge leak?

A leak rate on a Remstar can't be that low. However if DreamStalker's and my math both suck, I would hate to say where the math of the Respironics people lies.

We have seen others on the forum post numbers they get off LED panels on the Remstars that don't make sense. The reading of 1.9 fits into the category. The reading of 30.6 makes sense and based on your graph interpretation (Robbieh had posted the graph in June too) it sounds like you are RIGHT ON !!!.

viewtopic.php?t=20984

lking · Post by **lking** » Sun Dec 02, 2007 1:28 pm

jules wrote:A leak rate on a Remstar can't be that low. However if DreamStalker's and my math both suck, I would hate to say where the math of the Respironics people lies.

It beats me but my two machines definitely use/used different types of readings for the leak rate.

jules wrote:The reading of 30.6 makes sense and based on your graph interpretation (Robbieh had posted the graph in June too) it sounds like you are RIGHT ON !!!.

Thank you for giving me your inciteful information! I feel much better now.

jules · Post by **jules** » Sun Dec 02, 2007 1:44 pm

The firmware written for the m series isn't that great. Days of data are lost. Weekly averages aren't always right. I don't think it is the Remstar machines reporting different kinds of data but more of the firmware/software being poorly written.

Encore Pro math isn't that great either with lots of round off errors and further errors being propagated.

Resmed reports excess leaks (over the menu mask type) in liters/sec.

Remstar report real leaks (when they decide they want to) in liters/min.

Country4ever · Post by **Country4ever** » Sun Dec 02, 2007 2:24 pm

Are the vent flow rates the "leak" level that one should expect? And then anything above that is......well, above that.
So.....if my LED says I have a leak rate of .29 l/sec and I take that times 60 I get 17.40 l/min.......what does that tell me, if I can't find any info anywhere that says if that's good or bad?? Oh.....and would I substract the vent flow rate from that, to get my true leak rate? But the graph I found doesn't label things, so I don't know what the 29 really means.
Jules, I can't seem to get that first link to open. I have dial-up so maybe I just can't open it.
I did find one little pamplet that came with my swift pillow, but it doesn't have a page 11.

jules · Post by **jules** » Sun Dec 02, 2007 2:49 pm

I have an old Swift but I have the paperwork from it. Inside the front cover is a section F Pressure Flow Curve with a graph and chart. This ts what I assume Resmed put into their firmware for the machine.

The number you are getting on the LED is what is EXCESS or what is above what you are supposed to be. The .29 translates to 17 L/min over what you are supposed to be. (again for a pressure of 8, you add the 17 to 29). You are 17 higher than what you should be. Excessive yes but again not alarming. Some people have leak rates more than twice what they should be.

If your pressure was 20 which corresponds to a flow rate of 49 on the chart then I wouldn't find having an excess of .29 or 17 L/min disturbing, but your pressure is probably under 8 so I do find that level disturbing and hence there is a need to figure out where it is coming from.

Again I suggest looking at some of the swift fixes and seeing if you can lower the leak rate with those. I suggest you make sure you have the machine off when you take off the mask even for a pit stop during the night. These are ideas that would lower the leak rate for many and with these you might find that your can get your LED number down and then have a better idea that your treatment is working.

However, as I just posted on your other thread, you need to get the software or do a titration study with a wider range for your pressures.

Country4ever · Post by **Country4ever** » Sun Dec 02, 2007 4:17 pm

Thanks Jules,
Is there a list somewhere of what is considered acceptable vs unacceptable leves of leaks?
I think my leaks are from mouth breathing. I have a cheap chin strap that I will try, but I have the feeling I will still be able to mouth breath.
I've read about the polident and the taping and need to think more about those options.
Why should we even care what the vent flow rate is, if, when we figure out our leak rate, it doesn't really come into play? What I mean is, from what I think you've said, it doesn't matter if the vent flow rate is 29.....my leak rate of 17 l/min is what I should look at. Aren't you saying that the LED doesn't include the vent flow rate?
And what does their "29" mean in that table.......is that also l/min?
Thanks for your help!

jules · Post by **jules** » Sun Dec 02, 2007 4:53 pm

to me it is a relative measurement of excess in leaks versus expected vent flow - I don't have an specific chart of what is and isn't acceptable but I tend to use a guideline of being off by 30 % needs more examination - you exceed that

the 29 is in L/Min - that is specified in the chart label

we don't know your pressure just that 8.2 would be the highest it would be - a lower pressure would have a lower flow rate and if your pressure is lower than 8 most of the night, then your leaks are WORSE relative to the expected vent flow

Get the software - I need pictures to comment further.

Country4ever · Post by **Country4ever** » Sun Dec 02, 2007 4:57 pm

Thanks Jules,
I'll need to ruminate on this awhile!

ozij · Post by **ozij** » Sun Dec 02, 2007 10:24 pm

We care about vent flow when our machines and masks are not made by Resmed.

O.

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