Looking at mask leak rates

John_M · Post by **John_M** » Tue Jun 12, 2007 10:53 pm

This poll is about looking at what CPAPtalk members "accidental" leak rates are and what members do to reduce leak rates.

See http://sleepapnea.wikia.com/wiki/Mask_Leak_Rate for a general discussion of mask leak rates

The "accidental" leak rate is the actual measured leak rate reported on the machine LESS the intentional leak rate for your mask at the operating pressure. (Note that some machines automatically take the intentional leak rate into account). You can determine the intentional leak rate for your mask at the operating pressure by finding the intentional leak data in the instructions that came with the mask or perhaps finding your mask in this table http://www.internetage.com/cpapinfo/leak-rates-1.html

In the next post I will give an example of how I did this for myself.

In this discussion, I suggest we discuss
1/ the significance of mask leak rates, i.e. how much of a leak rate is tolerable and
2/general strategies to reduce mask leak rates.

I suggest we stay away from individual fixes for individual mask types, but just discuss strategies that work for all masks.

Looking forward to learning about mask leak rates

John M

andyomega · Post by **andyomega** » Tue Jun 12, 2007 11:17 pm

ive never measured the leak rate.
But I do know that my autopap machine takes care of my leaks by increasing the pressure.

John_M · Post by **John_M** » Tue Jun 12, 2007 11:24 pm

Encore Pro Analyser is showing that my total leak rate is averaging about 42 liters/minute total leak rate at constant pressure of 9 cms H2O for the ComfortFull 2 mask I am using.

The table on the last page of my instruction manual shows that the intentional leak rate for the mask is 28 liters/minute at 9 cms H2O.

The table on http://www.internetage.com/cpapinfo/leak-rates-1.html shows an intentional leak rate of 30 lpm for 10 cms H2O so I guess that 28 lpm is a good number.

So my "accidental" leak rate is 42-28= 14 liters per minute.

My Encore plots show that the leak rate very occasionally goes down to 30 lpm or below but usually stays up in the 50 lpm area with occasional excursions higher.

I don't know if a accidental leak rate of 14 lpm is OK. My AHI's look nice, about 1, but I don't know if that is because the machine is not picking up AHI's because of the relatively high accidental leak rate.

I have tried Lasinoh http://sleepapnea.wikia.com/wiki/Mask_Leak_Rate to stop the leaks but that didn't seem to help.

I found that mouth taping reduced my leak rate when I was on the Swift nasal pillow mask so these days I either tape or use a Full Face mask.

My current strategy is to keep on trying on new masks until I find one with an "acceptable" leak rate. Once I have done that I plan to keep on swapping masks until I find one that is both comfortable and has a low leak rate.

I have found Mask Roulette viewtopic.php?t=19546&highlight=mask+roulette to be very useful. I have received masks to try at a mailing cost of $4.60 for each trial.

So where are you at on your leak rate?
What have you learned about how to reduce leak rates.

Comments, suggestions and poll entries very welcomed

John M

mhacker · Post by **mhacker** » Thu Jun 14, 2007 9:48 am

I am still trying to figure out the definitions. Then I will know what the loss is.

What is the average score? What average are they using?
What is 90%? 90% of what? I found out other machines use different values so this really confusing.

I have heard that 12 l/m loss was a goal but have not seen proof of the concept yet.

i suspect mine is 14 to 16 l/m - mask loss is 28-30 and average is 42-46

mb

Guest · Post by **Guest** » Thu Jun 14, 2007 10:15 am

mhacker wrote:I am still trying to figure out the definitions. Then I will know what the loss is.

What is the average score? What average are they using?
What is 90%? 90% of what? I found out other machines use different values so this really confusing.
.....

mb

Respironics reports Max leak rate, 90% leak rate and average leak rate.
90% leak rate is that leak rate which is above 90% of the leak rates observed.

In the poll I am suggesting we post the accidental leak rate which is the average leak rate less the mask intentional leak rate at that pressure.

Hope that helps. It is rather complicated but as different masks have different intentional leak rates which vary with pressure, I thought that this was the most meaningful number to look at

John M

DreamStalker · Post by **DreamStalker** » Thu Jun 14, 2007 10:18 am

mhacker wrote:I am still trying to figure out the definitions. Then I will know what the loss is.

What is the average score? What average are they using?
What is 90%? 90% of what? I found out other machines use different values so this really confusing.

Basically there is a normal mask CO2 vent rate unique to each mask at a specific pressure.

I have heard that 12 l/m loss was a goal but have not seen proof of the concept yet.

i suspect mine is 14 to 16 l/m - mask loss is 28-30 and average is 42-46

mb

90% refers to the 90th percentile ... meaning that 90% of the measured daily values were at or below the 90th percentile value. Your machine samples the values throughout each 24-hour sleep session(s) and caluculates the statistical 90th percentile value for that 24-hour period.

Average 90% refers to the simple arithmetic average of your daily 90% values. Respironics machines use 90% whereas ResMed uses 95% stats.

With regard to leak stats, ResMed subtracts normal CO2 vent rates for masks (based on ResMed brand mask setting) and does so using units of L/s instead of L/m (multiply ResMed leak values by 60 to convert to L/m). Respironics machines provide leak and CO2 vent rates as a sum so you have to subtract your own mask vent rate from the provided "Respironics leak" rate data based on your type of mask and pressure ... doing so gives you the value for all other non-normal leaks such as mask leaks, hose/connection leaks, and mouth leaks (for nasal interface users).

Never seen any proof myself for 12 L/m loss as a "goal". I would think a percentage of the normal mask CO2 vent rate would be a more practical figure to shoot for (maybe 5 or 10% ??? ... dunno).

No need to suspect leak loss values if you have a machine capable of providing efficacy data (seems like you do based on your profile info) ... it should tell what your leak rate is fairly precisely. Subtract your mask CO2 vent rate (found in users manual) to determine problem leaks.

DreamStalker · Post by **DreamStalker** » Thu Jun 14, 2007 10:21 am

Anonymous wrote: ...
90% leak rate is that leak rate which is above 90% of the leak rates observed.
...John M

I don't think that is correct John .. see above post.

tillymarigold · Post by **tillymarigold** » Thu Jun 14, 2007 11:12 am

Silverlining reports mask leak rates in l/s instead of l/m and my Hybrid's manual shows a graph rather than listing numbers by pressure (and the graph is in increments of 10 l/m with pressures marked in increments of 2cm so it's rather hard to read). So in other words, I look at my leak rates as infrequently as possible.

However, my average leak rate is usually about .40-.45 l/s which is 24-27 l/m, and I think my Hybrid should be leaking between 35-40l/m. So I put "between 0 and -10."

My upper leak amounts are usually about .6 l/s which is 36l/m so I'm good there too. I think.

christinequilts · Post by **christinequilts** » Thu Jun 14, 2007 11:35 am

DreamStalker wrote: With regard to leak stats, ResMed subtracts normal CO2 vent rates for masks (based on ResMed brand mask setting) and does so using units of L/s instead of L/m (multiply ResMed leak values by 60 to convert to L/m). Respironics machines provide leak and CO2 vent rates as a sum so you have to subtract your own mask vent rate from the provided "Respironics leak" rate data based on your type of mask and pressure ... doing so gives you the value for all other non-normal leaks such as mask leaks, hose/connection leaks, and mouth leaks (for nasal interface users).

Except ResMed just had to change things on the VPAP Adapt to confuse me Being a long time Respironics user, I knew leak rates in L/min- that was my 'native language'; and I knew you had to 'translate' ResMed's L/second to compare. It was a trade off, on one hand, you had convert L/sec to L/min; on the other hand, you had look up your masks leak rate & subtract it yourself. Either way, there was a little math involved. Then I get my Adapt and its in L/min, what's with that? I swear I was trying to covert to L/sec & then back again the first week because I just knew I had to do something with the numbers...there was no way I could just use the numbers 'as is'-lol

As for my true leak rate, above expected mask vent, it's around 15-18L/min, average. Some nights worse, some nights better- I have to wonder what I did those nights when I have an average leak of 3L/min all night (or maybe its what I don't do?). When my cat got my hose, it was surprising my leak rate didn't go up much overall, but the 'grade' (Excellent, Very Good, Good, Poor) the Adapt gives me for leaks was consistently worse- that's how I knew something was up.

oceanpearl · Post by **oceanpearl** » Sat Jun 16, 2007 7:35 am

Hybrid leak rate??

mhacker · Post by **mhacker** » Sat Jun 16, 2007 8:58 am

DreamStalker wrote: wrote:units of L/s instead of L/m

christinequilts wrote: wrote:you had convert L/sec to L/min; on the other hand, you had look up your masks leak rate & subtract it yourself

At least they stayed metric, can you image trying to convert "imperial gallons per fortnight" back into l/m?

mb

oceanpearl · Post by **oceanpearl** » Sat Jun 16, 2007 9:02 am

Anyone have the leak rate for the Hybrid??

Goofproof · Post by **Goofproof** » Sat Jun 16, 2007 9:18 am

andyomega wrote:ive never measured the leak rate.
But I do know that my autopap machine takes care of my leaks by increasing the pressure.

Not so your machine trys, to provide enough volume of air, to overcome the leak.

That does NOT mean, it was sucessful, in reaching the pressure you need to keep your airway open.

Leaks Matter, if you want sucessful treatment. Jim

John_M · Post by **John_M** » Sat Jun 16, 2007 9:36 am

oceanpearl wrote:Anyone have the leak rate for the Hybrid??

Yes, I found it on
http://www.internetage.com/cpapinfo/leak-rates-1.html

There is now a Sleep Apnea Wiki page on the Hybrid at
http://sleepapnea.wikia.com/wiki/Hybrid ... _Interface

Additions welcomed.

Happy Happy day. There is a Hybrid coming my way for me to try!!!!

Thanks alpha

John_M

tillymarigold_ · Post by **tillymarigold_** » Sat Jun 16, 2007 10:02 am

John_M wrote:
oceanpearl wrote:Anyone have the leak rate for the Hybrid??
Yes, I found it on

Wish that chart didn't start at 8.0cm though. My range is 6.0-10.0 and only goes over 8 on my bad nights. (Which is about once or twice a week.)

I was wrong, the chart on the Hybrid manual's cover goes up in increments of 20L/m and 5cm.

But here's my "best guess" at leak rates for lower pressures.

5: 32
6: 37
7: 40

My guesses at higher pressures were off by about 1L/m so keep that in mind.

Looking at mask leak rates

What is your accidental mask leak rate ?

Looking at mask leak rates

John's leak rate.

Anyone have the

Re: Anyone have the