Leak vs. venting?

[jhsellers]

How does a machine (or software/firmware) differentiate between vented air and leaks?

This might not apply for all masks - I'm not sure that nasal pillows are vented? But most all full-face masks, and nasal masks (at least for ResMed products) are vented style.

So, how is this difference accounted for? Or is the vented air considered a baseline for leaks?

Thanks,
John

[Sleepster]

Each mask has an intentonial leak rate that depends on the pressure. For example, my mask has an intentional leak rate of 30 L/min at a pressure of 11 cm. I find this out by looking at the mask manufacturer's website or literature.

The CPAP machine has a low-inertia flow rate meter that measures the total leak rate.

The unintentional leak rate equals the total leak rate minus the intentional leak rate.

Different machines and different software packages display this information differently. On your ResMed machine all you can see is the unintentional leak rate, which the manufacturer recommends you keep under a specific number, 24 L/min IIRC.

I look at the total leak rate as my favorite software, SleepyHead, can't account for the intentional leak rate for my BiPAP. BiPAP's operate at two pressure levels, so the intentional leak rate is a bit harder to calculate. Your machine operates at a variety of pressure levels so calculating the intentional leak rate would be even harder. As far as I know, ResMed machines won't reveal the total leak rate or the intentional leak rate. They do the calculation in secret and reveal only the unintentional leak rate.

[Sleepster]

This might not apply for all masks - I'm not sure that nasal pillows are vented?

All masks are vented. The measurement of this venting is called the intentional leak rate. Without it we'd re-breathe our exhaled carbon dioxide and suffocate.

[jhsellers]

Thanks, Sleepster.

From what you've said, I conclude that the venting is the "intentional" leak rate. (or at least it's part of it....)

I've seen the graphs you mention, of flow rate vs. pressure, and leak rate (venting) vs. pressure. Between these performance parameters, and the plethora of data I get from ResScan, I've been overwhelmed to know much about what all the data means yet. I'm just trying to keep consistent with the treatment, and keep the mask fitted all night without many leaks.

I just got a Quattro FX mask to replace the Mirage Liberty I was using. The Liberty replaced a Mirage Quattro I started with that left my nose bridge bloody. I think I really like this Quattro FX - I was being sorely irritated with the nasal pillows. Got used to them eventually, with help from lanolin cream, but this Quattro FX is really comfortable. And it seems to leak less than the other masks also. I'm not yet sure I have the correct size, but the fitting guide says so. It doesn't sit on face all night like the ResMed photo checks say it should stay, but I'm still in the early works with it.

All this should probably go in another post about the Quattro FX mask, but I'll feign newbyness since I'm still in my first year of using the CPAP.

Thanks for all the help you guys offer.
John

[trish6hundred]

Hi jhsellers, WELCOME! to the forum.!
What Sleepster said.
Keep checkin' in for more responses to your post.

[Sleepster]

From what you've said, I conclude that the venting is the "intentional" leak rate. (or at least it's part of it....)

All of it. Well, they may allow for some additional leaks where the mask meets the face, but I find those make so much noise I have to eliminate them entirely.

I've been overwhelmed to know much about what all the data means yet. I'm just trying to keep consistent with the treatment, and keep the mask fitted all night without many leaks.

The two important things are the AHI and the leak rate. You want to keep your leak rate below that line that ResMed sets, I think it's 24 L/min. You also want to try to get your AHI to stay below 5 if possible.

I just got a Quattro FX mask to replace the Mirage Liberty I was using. ... It doesn't sit on face all night like the ResMed photo checks say it should stay, but I'm still in the early works with it.

Wearing the mask every time you sleep and getting a good fitting mask are fundamental. You're working on the right things. Just keep in mind that it's no crime to have to switch masks several times to get the right one. Insurance companies and equipment providers understand this and make allowances for it.

[zonk]

all vented masks are designed with vents to flush out exhaled air
full face masks have anti-asphyxia valve which allows you to breathe room air in case power goes out

the vents leak called intentional leak .... good leak
different types of masks have different vents leak rate so you need to select the correct type of mask that you,re using on the S9

Resmed machines unlike other machines take into account the type of the mask that you,re using and subtract intentional leak from total leak and report unintentional leak ... unintentional leak (mask leak plus mouth leak)
Resmed define acceptable unintentional leak anything below 24 L/min which is the red threshold line shown on Resscan leak graph
the lower the better ... higher leak may affect the accuracy of data and sleep quality

in general full face masks cover large area on the face and prone to leak more than nasal or nasal pillows
nasal masks don,t irritate as nasal pillows and more manageable than full face masks

edit: Quattro FX fit different than the Quattro. you need to place the cushion at an angle on the nasal bridge and swing (swing and seal)

http://www.quattrofx.com/quattrofx/en/index.html

[PaulaO2]

And not all leaks come from the mask itself (as in badly placed).

I had my leaks under control, or so I thought. then I started noticing the leak rate was spiking again but I couldn't figure out why. Until two nights ago.

I had gone to bed and was arranging the hose for the night. I realized that when I moved the hose in a certain direction, I could hear air hissing. It took a bit to find it. I had a hole in my mask hose! I can't see it, but I can feel it and hear it.

I had a spare hose and put that on. Leaks are still up the next morning. Yep, another hole. Since I was out of spare parts and this hole was smaller, I just put a piece of Duct tape over it. I'll call the DME Monday to get another one.

[Sleepster]

Since I was out of spare parts and this hole was smaller, I just put a piece of Duct tape over it. I'll call the DME Monday to get another one.

Duct tape is good stuff!

[zonk]

Since I was out of spare parts and this hole was smaller, I just put a piece of Duct tape over it. I'll call the DME Monday to get another one.

Duct tape is good stuff!