New user asking about leak rate

First, before asking my question, I want to say thanks to all the people who post to this incredible forum. I was just diagnosed with severe obstructive sleep apnea a few weeks ago. After the sleep center essentially handed me a list of local DME providers and told me to go get a CPAP machine without any further guidance, I was lucky to be able to educate myself here before making any decisions. So, thanks for offering your hard-won insight in such a friendly manner.

Now, for the first of what will probably be many questions:

I have a RemStar Pro with C-flex set at 14 cm and a Swift LT mask. I've tolerated the machine fairly well, but I'm a bit confused about the leak rate. The specifications in the manual for the CPAP machine say "Maximum Flow: 35 LPM" but the 7-day leak rate for each of the past three nights has been over that (39.8, 46.9, and 51 LPM).

How can I be leaking more than the machine is capable of delivering?

I know that the leak rate is something I'll need to work on (I'm a mouth breather with congestion issues), but first I want to make sure I understand the data correctly.

I appreciate any help that can be offered.

The leak rate in your mask manual indicates how much leak your machine can compensate for at your pressure setting.

Anything over that is the leak you have to be concerned about and try to get down (closer to or at the rate in the mask manual).

You say you are mouth breathing and this may be why the rate is higher. You need to deal with the mouth leaking if that's the problem, by using a full face mask or taping.

Hawthorne wrote:The leak rate in your mask manual ...

Did you mean to say "machine manual"?

LinkC wrote:

Hawthorne wrote:The leak rate in your mask manual ...

Did you mean to say "machine manual"?

The mask leak rates are in the user manuals that come with the masks.

Edit: In the mask user manuals, it's referred to as "Vent Flow Rate".


Den

Thanks, Hawthorne, for that quick answer. The manual says the mask should vent around 35 LPM at 14 cm, so it looks like I have a ways to go to bring the leaking down (especially since I seem to be headed in the wrong direction!).

Here's another question: When people talk about taping, do they tape parallel or perpendicular to the lips? (Or do they put the tape over their partners ears?)

floboots wrote:First, before asking my question, I want to say thanks to all the people who post to this incredible forum. I was just diagnosed with severe obstructive sleep apnea a few weeks ago. After the sleep center essentially handed me a list of local DME providers and told me to go get a CPAP machine without any further guidance, I was lucky to be able to educate myself here before making any decisions. So, thanks for offering your hard-won insight in such a friendly manner.

Now, for the first of what will probably be many questions:

I have a RemStar Pro with C-flex set at 14 cm and a Swift LT mask. I've tolerated the machine fairly well, but I'm a bit confused about the leak rate. The specifications in the manual for the CPAP machine say "Maximum Flow: 35 LPM" but the 7-day leak rate for each of the past three nights has been over that (39.8, 46.9, and 51 LPM).

How can I be leaking more than the machine is capable of delivering?

I know that the leak rate is something I'll need to work on (I'm a mouth breather with congestion issues), but first I want to make sure I understand the data correctly.

I appreciate any help that can be offered.

I think what you're referring to is this:

Pressure
Pressure Increments: 4.0 to 20.0 cm H2O (in 0.5 cm H2O increments)
Pressure Stability: 4.0 to 20.0 cm H2O (±1.0 cm H2O)
Measured in accordance with EN ISO 17510-1 @ 1/3, 2/3, and Pmax with BPM set to 10, 15,
and 20 BPM @ 68° F (±9° F) (20° C ±5° C), 50% RH (±5%).

Maximum Flow: 35 LPM
Measured in accordance with EN ISO 17510-1 @ 1/3, 2/3, and Pmax with BPM set to 10, 15,
and 20 BPM @ 73° F (±3.6° F) (23° C ±2° C), 50% RH (±5%).


There was a lengthy (and confusing) discussion about that some time ago. But, basically, it's not what you're trying to compare. In other words, it's an "apples and oranges" comparison.

What the mask user manual is referring to is the "Vent Flow Rate" (usually referred to as "Leak Rate")......which is the typical exhaust rate that is "normal" at a stated pressure for exhausting the CO2. It's not at all unusual to be a few LPM over the stated VFR.
To further confuse this "Leak Rate" issue is that the machines record "Average Leak", "90% Leak" and "Large Leak".


Den

Hawthorne wrote:The leak rate in your mask manual indicates how much leak your machine can compensate for at your pressure setting.

Let me put it another way. How could the MASK manual know what machine you have and its ability to compensate?

Yes, of course "Vent Flow Rate" is in the mask manual, but anything indicating "how much leak your machine can compensate for" would be in the machine manual. The VFR merely tells you how much you can write off as "normal" and not count as unintentional leakage.

Eeeeeeh gads, y'all, this is so confusing! Newbies'll all run shrieking in frustration trying to make sense of this information.

I could be very wrong here but it sounds to me like this thread so far is a discussion of how Respironics xPAPs report leaks.

As I understand it...again I might be wrong...on ResMed xPAPs you define the mask you are using (if a ResMed mask) or "Standard" (if not ResMed) and that tells the xPAP the mask's intentional vent rate (sometimes called the mask's leak rate) which is designed into the mask in order to clear your exhaled CO2. (The standard setting uses '24' as the intentional vent rate.) Then, the machine reports the calculated leak rate (difference between delivered and the exhaled pressures+intentional vent rate) and that is the amount of leak that is unintentional leak -- the type you need to chase down and reduce. In other words, after you define your mask in a ResMed xPAP, you just read the reported leak rate to know whether you need to go chasing leaks. With the right mask, the reported leak is slight. With higher leak rates, ya hafta join the rest of us in chasing leaks and eliminating them.

I have no idea how other manufacturers report leak -- maybe others can add to the collective information.

Muse --

You've got ResMed's leak calculation down pat.

Respironics (and I believe all other manufacturers) just report total leak. So you have to look up the intentional leak for your mask at your pressure and subtract that from the reported leak to see the unintentional leak that you can try to eliminate.

And, with ResMed, instead of using the Standard setting for non-ResMed masks, you can take a look at the intentional leak chart for your non-ResMed mask and find the ResMed mask with the closest intentional leak chart. They're online at ResMed.com. Setting your machine to the setting for that ResMed mask should give you the best leak report from your machine. (For anyone in the upcoming challenge, the Swift setting should work well for the F&P Opus 360.)

Muse-Inc wrote:Eeeeeeh gads, y'all, this is so confusing!

No, it really isn't. The only thing confusing is different manufacturers (and users) have different terms for the same thing. And often those terms are applied incorrectly.

VENT = designed airflow to purge mask. LEAK = unintentional leakage (seals, pillows, mouth, etc.)
TOTAL = VENT + LEAK

Each mask has a designed VENT rate, which goes up as the pressure does. This flow flushes out the CO2 during exhale. Since it's "built-in" and relatively constant, it's not really a "leak" (at least not one you can--or want to--fix). As such, you can subtract that amount from the TOTAL reported by the machine to get your actual LEAK rate (which you should minimize).

*Respironics machines report the TOTAL and YOU do the math, subtracing the mask VENT rate from the TOTAL. ResMeds do the math and report just the LEAK, subtracting the VENT of the mask you tell it you're using at the pressure the machine is set for.

All brands (that I'm familiar with) can compensate for some level of LEAK, keeping the desired pressure in spite of the LEAK.

Correct me if I'm wrong (and I'm sure someone will!), but I believe a "LARGE LEAK" (to use Respironics term) is a level beyond which the machine can't compensate. The machine assumes the mask is leaking badly and decreases the pressure in an attempt to re-seal the mask. This condition is shown as a black bar on the charts.

LEAK and LARGE LEAK are what you should worry about...and minimize.