Looking to understand data and charts

GaryG wrote:I think the allowable leakage rate may be mask dependent. Maybe someone more experienced can comment on allowable leakage rate.

Yes, each mask has it's own "intentional flow" rate chart, which should be available in the booklet or instructions that came with the mask.

I'm not sure how F&P machines handle the issue of reporting leak. A ResMed machine (once you've input the mask you're using) will account for that mask's intentional leak at whatever your pressure setting is. So they report only the leak that's OVER AND ABOVE what it should be. So if your mask's intentional leak rate at your pressure is 35 lpm and your data is reporting a leak of 10 lpm, your leak is 10 lpm. If there was no leak, it would show as 0.

On Respironics machines, there's no inputting of info re: the mask being used, and the reported leak is the total leak and must be compared to the intentional leak rate for that mask at that pressure. For instance, if my mask's intentional leak rate at my pressure is 30 lpm and my data indicates leak of 45 lpm, then my actual leak is 15 lpm. Respironics requires math.

I hope that makes sense.

BleepingBeauty - So, just to confirm...since i don't think my machine has any data about my mask, I actually need to subtract roughly 25 to 36 from the data in my charts to account for the intentional flow rate to get my actual leak numbers?

jccameron wrote:BleepingBeauty - So, just to confirm...since i don't think my machine has any data about my mask, I actually need to subtract roughly 25 to 36 from the data in my charts to account for the intentional flow rate to get my actual leak numbers?

Correct, jc.

Thanks for clarifying BB. Your comment should be in a sticky at the top (Maybe it already is and I missed it there). I was concerned with jccameron's leak rate, but sounds like his machine isn't correcting, so maybe he's ok (assuming the allowable rate for Quattro is comparable to Liberty.)

jc and GaryG,

The best way to adjust your mask properly is to do so laying down, hooked up to the machine, which is blowing at your full (or max, if you're using a range) pressure. Make small adjustments to the headgear while laying on your back. Then turn your head and/or body each way, as when you sleep on your side, and check for leaks. Make a small adjustment to the strap nearest to the leak.

If you do this at full pressure and obtain a good fit, you won't have to worry about losing a good seal if/when you reach your high pressure during the night.

Think about this: Lots of people have higher pressures than yours. If they're able to get a decent fit on their mask, you can, too.

Assuming you don't have a resmed machine -------- my approach ------

If you take your cpap machine's reported flow rate and divide it by the mask intentional flow rate --------- you get a number -

if that number exceeds 1.2 start looking for where things are wrong.

For example you get your flow rate as 32 and your mask is supposed to be 28

32/28 is approximately 1.14 -------- sounds good

however if your flow rate is 45 and your mask is supposed to have a flow rate of 36

45/36 = 1.25 ---- you got trouble

This can be adapted to resmed machines but requires more arithmetic and you need to know what mask is in the menu and it's flow rate as well as the flow rate of your own mask and the LED 95 %ile leak information.

Gary -------- my approach trashes the 24 l/min that resmed seems to want to use for acceptable leak rates. I prefer to use a 20 % above what the mask should be.

If your leak rate with the liberty is 24 l/min over the flow rate in the manual I suspect you have problems. Do you have the software to start looking at what part of the night the leaks are occurring?

Jules, so are you saying if Mike's intentional leak rate at his pressure is 42 lpm, would anywhere up to 50 lpm(20% higher) be acceptable? I hope so because sometimes he's in the 47-49 range on restless nights.

jules wrote:Gary -------- my approach trashes the 24 l/min that resmed seems to want to use for acceptable leak rates. I prefer to use a 20 % above what the mask should be.

If your leak rate with the liberty is 24 l/min over the flow rate in the manual I suspect you have problems. Do you have the software to start looking at what part of the night the leaks are occurring?

Here's my posting from a few days ago.
viewtopic.php?f=1&t=45367&p=406332#p406332

BleepingBeauty wrote:jc and GaryG,

The best way to adjust your mask properly is to do so laying down, hooked up to the machine, which is blowing at your full (or max, if you're using a range) pressure. Make small adjustments to the headgear while laying on your back. Then turn your head and/or body each way, as when you sleep on your side, and check for leaks. Make a small adjustment to the strap nearest to the leak.

If you do this at full pressure and obtain a good fit, you won't have to worry about losing a good seal if/when you reach your high pressure during the night.

Think about this: Lots of people have higher pressures than yours. If they're able to get a decent fit on their mask, you can, too.

My machine has a mask fit feature. I put the mask on, use this feature, which says my fit is excellent, mask fits fine, then I go to sleep and wake up with pillows sometimes not fitting properly. But its fine when I go to sleep.

GaryG wrote:My machine has a mask fit feature. I put the mask on, use this feature, which says my fit is excellent, mask fits fine, then I go to sleep and wake up with pillows sometimes not fitting properly. But its fine when I go to sleep.

I don't know how that feature works, but I'm betting (on logic) that, as you move around in your sleep, the mask no longer fits you as well as your machine says it does when you're awake and testing it.

Interesting data, since I like others haven't seen that machine before. Agree with a lot of the advice that's been given so far. First and foremost is your mask fit, since if you don't have that, you can't really interpret your data.

Did some sniffing around to look at the F&P manuals et al and it looks like they report straight leak rates. For the Quattro, your intentional leak rate should be around 32 at 8 cm, 41 at 12 cm (+/- 6L) per their flow chart - hence when you see a number well above 50, it tells you something's not right. If you weren't wearing a full face mask, that'd be my first suggestion, but since you are it's clear your fit isn't there.

The way to think about it is that if your mask doesn't fit, it doesn't matter how hard your machine is blowing, since you can't splint open your airway if the air isn't actually getting there. That makes some of the 11 cm pressure readings on the last couple of nights suspect, because it looks like the mask was pretty much dislodged. A proper mask fit also takes more than 30 seconds, so shame on your DME.

I'd also agree to raise the minimum a bit (to roughly what your sleep study showed as a constant pressure) but that can wait until you get good data to work with.

The only other comment I'd make is that after looking at how SensAwake works, I'd turn it off for now (if you can - I couldn't find a manual for your specific machine to see if there's a toggle). It sounds neat, but it drops pressure because it thinks you're awake - which admittedly can be annoying to find your machine maxing out and thinking you have an event because you're moving around in bed trying to fall asleep.

The problem with that when you're titrating (as you are) is that I suspect it can interfere with trying to find a good pressure. If you look at your first day's graph at hours 4-5, you have the SensAwake feature dropping your pressure - which seems to correspond with a hypopnea (and later, an apnea, although it looks like it may have gone back up by then). Basically, I suspect it'll be a nice feature to have going forward, but for now it's going to make things more difficult.

And don't worry about ripping your mask off. We all did that at first.