ASV SleepyHead Data definition question

Looking at my SleepyHead data, I would like to understand something. I use the Oracle mask on the Resp. ASV machine and note that my leak line never crosses the 8oL/min threshold for declaring a leak.

So, the Total Leaks curve simply seems to be displaying the normal venting of the mask, correct?

What then is the "Leak rate" line that occasionally shows up on my graph in purple. (90% 2.00 and max 3.00)? What does "Leak rate" mean?

I don't think I need to upload a picture for this question, but let me know and I will do it right away.

Philips Respironics machines show the "Total Leak", which is all the air that goes down the hose. Mask vent, mask leaks, mouth leaks, holes in the hose, etc. It tries to estimate an "intentional leak," which is the air that is supposed to leak out through the exhale vent in the mask. It subtracts these two to show an "unintentional" leak which is the "bad leaks."

It's the second one you need to worry about most of the time. The total leaks like is useful to figure out things like a kinked hose, blocked air vents, etc.

ResMed machines only report their calculated "unintentional" leaks number, which is a mistake in my opinion.

I too, have been wondering about that.
So the smaller "leak" line is just the unintentional leaks. The rate of leaks beyond mask vent etc, or above ~80 cm.
That does not seem to correlate with what I remember seeing on my Sleepyhead.

archangle wrote:Philips Respironics machines show the "Total Leak", which is all the air that goes down the hose. Mask vent, mask leaks, mouth leaks, holes in the hose, etc. It tries to estimate an "intentional leak," which is the air that is supposed to leak out through the exhale vent in the mask. It subtracts these two to show an "unintentional" leak which is the "bad leaks."

actually, the respironics machines don't seem to have the math to calculate unintentional leak

the lower, unintentional leak line is jedimark's magic in sleepyhead.

photonic wrote:Looking at my SleepyHead data, I would like to understand something. I use the Oracle mask on the Resp. ASV machine and note that my leak line never crosses the 8oL/min threshold for declaring a leak.

So, the Total Leaks curve simply seems to be displaying the normal venting of the mask, correct?

What then is the "Leak rate" line that occasionally shows up on my graph in purple. (90% 2.00 and max 3.00)? What does "Leak rate" mean?

I don't think I need to upload a picture for this question, but let me know and I will do it right away.

it's an estimation, in sleepyhead, of excess leak over and above the calculated baseline venting rate of the mask.

As I recall, when setting up SleepyHead, there was a section that allowed for inputting normal leak rate data for your mask.
Then SleepyHead can calculate the excess leak rate from the total leak rate data that the Respironics machine provides.

So, the little graph line is the calculated excess rate line. Numbers like 2 or 3 seem pretty close to no leak at all.
An Oracle mask and a soft cervical collar should get you there.

So, did you enter the leak rate data from your mask user guide?

JDS74 wrote:As I recall, when setting up SleepyHead, there was a section that allowed for inputting normal leak rate data for your mask.
Then SleepyHead can calculate the excess leak rate from the total leak rate data that the Respironics machine provides.

So, the little graph line is the calculated excess rate line. Numbers like 2 or 3 seem pretty close to no leak at all.
An Oracle mask and a soft cervical collar should get you there.

So, did you enter the leak rate data from your mask user guide?

if you go back and check, that also says "not implemented" ... those numbers aren't used, and that section may be removed

Am I right in thinking that the total leak number is a moving target depending on the delivered pressure? For us ASV users, it seems that some nights have larger leaks than others and I have been wondering about that. I don't notice that my mask leaks vary as much as my numbers suggest.

M'ohms wrote:Am I right in thinking that the total leak number is a moving target depending on the delivered pressure? For us ASV users, it seems that some nights have larger leaks than others and I have been wondering about that. I don't notice that my mask leaks vary as much as my numbers suggest.

if you look in the back of the manual for your mask, you'll see a table, or chart, of expected leak (vent) rates at different pressures,

most masks vent from somewhere around 20lpm at 4cm to around 50lpm at 20cm .... within a few liters either way.

Sure, the leak rate for a mask is variable with pressure. With an ASV machine, the pressure can jump all over the place from pretty low (6-10 cm H2O) to pretty high (25 cm H2O) between breaths.
Take a look at the leak rate chart in your mask users manual.

On the Oracle mask the intentional leak rare at 9 cmH2O is 32 L/min but at 25 cm H2O it is 57 L/min.

palerider wrote: actually, the respironics machines don't seem to have the math to calculate unintentional leak

Actually they do and can. Encore Basic and Encore Pro both offer the user the ability to choose either Total Leak or Unintentional leak in their software reports. I think Mark used that ability to work his magic with SleepyHead.
I have compared Encore's Unintentional leak line to SleepyHead's unintentional leak line (that bottom line) and it is pretty much identical near as I can tell. Certainly close enough for what we want to use it for. The problem with using the unintentional leak line in SH as primary thing to look at we don't know where large leak territory is with that data point. We aren't ever told a set number like the ResMed's 24 L/min.

I never had enough large leak flags using Total leak to come up with any real idea where unintentional leak large leak territory might be but it very generous though...It's going to be well over 24 L/min for sure.

Maybe next week if I don't forget and have some time I will put together some comparisons of both leak reports. If you want to learn and I forgot just remind me.

Pugsy wrote:

palerider wrote: actually, the respironics machines don't seem to have the math to calculate unintentional leak

Actually they do and can. Encore Basic and Encore Pro both offer the user the ability to choose either Total Leak or Unintentional leak in their software reports. I think Mark used that ability to work his magic with SleepyHead.

Now that I think about it, I think the PRS1 machine only records total leak rate and Encore calculates an intentional and unintentional leak rate. I seem to remember Mark discussing this in the early days of SH on PRS1. He had to do quite a bit of work to calculate a good number for intentional leak rate.

archangle wrote: I think the PRS1 machine only records total leak rate and Encore calculates an intentional and unintentional leak rate.

The machine has to collect evaluate something and have some sort of calculation about leak for the software to be able to offer both total leak or unintentional leak reports. The software has to use some sort of data from the machine for it to offer those 2 reports. It can't just make it up as it goes. Software has to use the data from the machine....whatever data that might be.

I had a Respironics tech tell me that it (the machine) takes a baseline of sorts when the machine is first turned on to full pressure and subsequent calculations come from that baseline.

Pugsy wrote:

archangle wrote: I think the PRS1 machine only records total leak rate and Encore calculates an intentional and unintentional leak rate.

The machine has to collect evaluate something and have some sort of calculation about leak for the software to be able to offer both total leak or unintentional leak reports. The software has to use some sort of data from the machine for it to offer those 2 reports. It can't just make it up as it goes. Software has to use the data from the machine....whatever data that might be.

I had a Respironics tech tell me that it (the machine) takes a baseline of sorts when the machine is first turned on to full pressure and subsequent calculations come from that baseline.

Does the PRS1 machine display anything about unintentional leak? I know Encore displays unintentional leak, but is that calculated by the CPAP machine or by Encore? I know it displays large leak time, but does it ever display l/m leak rate numbers? I couldn't find any such leak info on my 550 machine.

The machine can only measure the airflow, pressure, temperature, and humidity. It has to derive everything else from that. That information can be derived in the machine itself or in the Encore software. Total leak is the average airflow down the hose. Intentional leak has to be derived from airflow, pressure, total leak, and mask type.

I think the PRS1 doesn't record unintentional leak on the SD card. Jedimark had to figure out to how to calculate unintentional leak from the total leak and pressure data for PRS1 machines. Look at this thread.

I presume that this means the PRS1 doesn't record unintentional/intentional leak data on the SD card, but I guess it could be there and Mark couldn't figure out how to read it.

I think Encore does the same thing, calculating unintentional leak data from the total leak and pressure data on the SD card plus (maybe) mask type.

Pugsy wrote:

palerider wrote: actually, the respironics machines don't seem to have the math to calculate unintentional leak

Actually they do and can. Encore Basic and Encore Pro both offer the user the ability to choose either Total Leak or Unintentional leak in their software reports.

Maybe next week if I don't forget and have some time I will put together some comparisons of both leak reports. If you want to learn and I forgot just remind me.

According to mark, there's no unintentional leak rate in the data stream, only total leak, and both he, and encore do mathy wizardy stuff to get the excess leak trace.

I'd love to see the comparinson, mark talks like he feels that his algorythm is better than the one in encore.