First night on bipap

[PaulaO2]

Yes, the 24L is the "acceptable" leak rate, as it the air coming out the exhaust port has to be accounted for. Anything over that says air is leaking elsewhere.

Full face masks are notorious for leaking. Try laying down during the day, mask and machine on, then moving around as you would assume you do at night. You can then figure out how to prevent it from happening at night.

[idahocouchpotato]

I just used the mask fit function where it skips the ramp up and get right down to business. After I figured out that the dial on the mask simply adjusts the tilt to match the slant of my face I was able to get the headgear set so it's comfy at full pressure, and it was reading a leak value of 0 on the screen. I rolled from side to side and even onto my stomach somewhat and there were no leaks.

I'll go rehash the cushion. I handle it with powder free nitrile exam gloves to keep fingerprints off when putting the clip back into the cushion.

Paula, the 24L leak rate needs to be associated with a pressure differential to have meaning. My max pressure of 20 cmH2O will leak more air through the exhaust ports than someone else with the same machine and mask but with a lower pressure. Also at a higher altitude a mask will leak more air than at sea level. If the machine just kicks in and calls anything over 24L/min a leak, I have no way of knowing if that number applies to my high pressure or was it set with a lower mask pressure as a standard.

That is why I wanted to know where the number comes from, whether stated in a manual or seen on a website so that I may tailor the info to my specific case.

[zonk]

unlike other machines ... S9 calculate unintentional leak (mask plus mouth leak)
You have to set the mask type (default is nasal)
unintentional leak = total leak minus intentional leak (leak from exhaust ports to flush exhaled air)

when you get Mr green smiley face means the 70th percentile leak is less than 24 L/min which is Good

[idahocouchpotato]

Thanks, Zonk! That is very good to know. I have made sure the machine is set to full face mode, and my face was green and smiley when I just did a proper fit. Not sure what changed from the DME to home, because there were no leaks in their office yesterday. Now I'm back to no leaks and will try again tonight.

[Sleepster]

Out of curiosity, Zonk, where did you find the 24L/min figure? If there was no leak at all, is that how much air should pass through the exhaust ports on the mask?

No. The intentional leak is the amount that passes through the exhaust port. It depends on your mask type and your pressure setting, but it's automatically subtracted by your ResMed machine so you never have to worry about it. In fact, you couldn't even if you wanted to as ResMed machines don't give you access to that information.

The 24 L/min refers to the leak rate over and above the intentional leak rate. This is called the unintentional leak rate and keeping it under 24 L/min is what's recommended by ResMed.

I'm not sure where zonk got that figure, but I'm sure he will provide you with links to the sources.

[archangle]

You need to watch your compliance hours. If your leaks are too high, it may not count the hours, and your insurance may refuse to pay for the machine. Learn how to read the "hours used" per night and days>4. You usually have to get something like 70% of the nights in 30 days to have more than 4 hours of "good" therapy or they'll take the machine back.

[idahocouchpotato]

Thanks for the info archangle. I know how to access the data from the machine thanks to this forum :grin:

I have private insurance so they don't check compliance data. Actually, after talking to them on the telephone I came to understand that because of a sizable deductible I will end up paying for most everything myself.

[idahocouchpotato]

I slept better and had a green smiley face for mask fit last night. I was really zonked out. :grin:

[trish6hundred]

Great, glad you had a good night last night and I hope thinks continue to go well for you.

[vsheline]

Out of curiosity, Zonk, where did you find the 24L/min figure? If there was no leak at all, is that how much air should pass through the exhaust ports on the mask? If so then the leak value would be a function of the mask pressure vs ambient pressure rather than a fixed value. I would like to research this further.

Welcome to the forum!

Keeping unintentional leak below 24L/min is a standard recommendation from ResMed.

If ResScan software reports the Leak is zero, this means the measured air flow into the hose is not larger than the amount the machine calculates is flowing through the mask vents.

The machine calculates airflow through the mask vents based on mask type and the pressure reaching the mask. So you have to tell the machine the mask type.

The machine calculates pressure reaching the mask (and you) as being the pressure at machine minus calculated pressure lost across the hose.

The machine calculates pressure lost across the hose as being the hose resistance times the airflow into the hose. So you have to tell the machine what type of hose is being used.

The resistance of the hose is an exponential function of the amount of air flowing through it. So the machine uses the amount of air flowing into the hose to calculate the resistance of the hose. Or, in other words, it calculates the pressure lost across the hose based on hose type and the amount of airflow into the hose.

Take care.
--- Vaughn