Sleepyhead - Avg Leak Rate?

[greatnitz]

Trying to interpret my 'Avg Leak' and what exactly it means. I have a pressure of 18, and my leaks average between 43 -55...what exactly does that number mean? What's a good number to be at?

[robysue]

Trying to interpret my 'Avg Leak' and what exactly it means. I have a pressure of 18, and my leaks average between 43 -55...what exactly does that number mean? What's a good number to be at?

I'm going out on a limb here, but I think that SleepyHead's average leak rate is just that---the average total leak rate for the night. (At least for the System One machines, SH reports total leak. Can anybody tell me what SH reports for ResMed users?)

Several notes:

1) Total leak rate includes both the intentional leak rate built into the mask (so we don't rebreathe our own CO2) and any unintentional leaking. Each mask has it's own intentional leak rate at various pressures. You need to look at your user guide to figure out what the expected, intentional leak rate for your mask at 18 cm of pressure is in order to determine what a reasonable total leak rate is.

2) Loosely speaking, you can interpret "average leak rate" as any average. For discrete data:

average value = (Sum of all the data points)/(number of data points)

Since there are a finite number of times the machine samples the leak rate data, you can basically think of the average leak rate as (Sum of all the sampled leak rates)/(number of times the leak rate is sampled). (Technically speaking, the leak is a continuous graph and the average value would be the area under the leak curve divided by the time the machine was running. In other words, the average leak rate is just the average height of the leak curve over the course of the night. The idea is that the area under the curve really can just be thought of as the sum of the data points and the length of time is then just the number of data points.)

3) "Average leak rate" is not the same as "median leak rate" on the S9.

4) The best way to judge your leak rate is probably not through a single number. Rather, it's the flatness of the leak line that's more important. In SleepyHead, however, the range of values on the vertical axis for the leak graph is chosen so that every minor bump will be visible. So in SleepyHead, you basically want your leak curve to stay around the expected leak rate for the graph +/- an "error" factor that is also usually listed in the owner's manual. So if your owners manual says that the expected leak for your mask at your pressure is 40 L/min +/- 5 L/min, then you want the leak curve to stay between 35 and 45 L/min for as much of the night as possible.

[Pugsy]

In your mask literature there should be a graph showing the intentional or vent leak rate at your pressure.
With full face masks and your pressures it is going to be to be more than my mask at my pressures. Vent rate goes up with pressure and with the type of full face mask.

You take that number and compare it to what SleepyHead is showing and the difference is excess leak.
I suspect that the excess leak will be minimal to none. I don't have the leak rate for your mask handy but at your pressure it is going to be in that 40 plus neighborhood.

Edit to correct bad misleading type. Sorry, didn't proof my composition well. Not one of my strong points.
SleepyHead reports Total Leak
The intentional vent rate plus any excess leak.

[robysue]

And yes.... SleepyHead is does report Total Leak plus excess leak.

Total leak plus excess leak would be equal to intentional leak + excess leak + excess leak
(Sorry about that pugsy, but I just couldn't let that one pass by without a comment)

[Pugsy]

http://www.resmed.com/us/assets/documen ... er_eng.pdf

page 11... looks like at 18 cm of pressure vent rate is around 50 L/min. There is always a little variance.
Your averages appear to be very near normal vent rate and minimal.

Ah heck Robysue I was trying to multi task.. not very well. Brain and fingers not working well together.
I will fix my typo.

[greatnitz]

Thank you all for the responses!

[davelikesbeer]

It would be great if SH allowed one to specify the mask in order to take the intentional leak into account.

[donaldm823]

When I was using a PR1, the avg leakrate reported was in the 60-70 and was concerned. Apparently the PR1 reports "total leakage". Found on the Resmed website that the Quatrro mask design venting rate was 54 for a pressure of 20, so your leakrate appears to be very low which is good. Now that I have shifted to the S9, it auto compensates for mask vent rate and only reports other leakage. My readout is usually in the 10 range with the S9 (was 65 with the PR1)

[Breathe Jimbo]

It would be great if SH allowed one to specify the mask in order to take the intentional leak into account.

Remember, it's a free program. It's a bit much to ask Mark to hunt down all stats for all masks on the market and maintain a current database for all masks with all leak rates at all pressures. It is much more reasonable to expect you to find the Intentional Leak in the manual that came with your mask, or on the manufacturer's web site.

Edit: If you have a ResMed machine and tell it which ResMed mask you are using, the machine makes the adjustment automatically and reports only unintentional leak, per Mark.

[Pugsy]

It would be great if SH allowed one to specify the mask in order to take the intentional leak into account.

That's an unrealistic expectation. The machines do not calculate it so software can't report what is not available.

If you wish to use Encore Pro there its default mode is to show unintentional leak only but can be changed to show total leak like SleepyHead. Even then it is not exact because Respironics does not have a setting on their machines to specify even just their masks individually much less all the masks available. ResMed S9 doesn't do specific mask models either. Theirs is just a general mask type.
The mask Resistance setting has nothing to do with calculating the leak intentional or unintentional.

I use Encore Pro and SleepyHead. When I use Pro set to show Total Leak it tells me my average leak is usually somewhere between 25 and 28 L/min. My mask at my pressure has a vent rate near 34.. It is not exact. There is no way to make it exact.

[davelikesbeer]

It would be great if SH allowed one to specify the mask in order to take the intentional leak into account.

Remember, it's a free program. It's a bit much to ask Mark to hunt down all stats for all masks on the market and maintain a current database for all masks with all leak rates at all pressures. It is much more reasonable to expect you to find the Intentional Leak (Vent Flow Rate) in the manual that came with your mask, or on the manufacturer's web site.

I agree. However, I think it should be possible to allow the user to enter some data into the program then SleeyHead could interpolate the vent rate for any pressure setting. Furthermore, it could even upload this data entered along with the mask type to create a database that then could be included in future versions.

The only reason I want such a feature is I because I use APAP and the mask vent rate changes throughout the night.

Once I have some free time, I will download the code and look into doing it myself. (I'm joking here since I never have free time )

Dave.

[Breathe Jimbo]

davelikesbeer, I'm sure Mark would love to have additional programmers helping with the development! I'm just a tester good at breaking things.