Is it normal that CPAPs dont register smaller leaks?

[vrapche031]

I've noticed in the past that my cpap almost never shows me that I had any leaks. I tried using the leak test function on it and sometimes it does catch the leaks and sometimes it doesn't. I thought that I maybe have a good seal but for the last 2 days I woke up with air leaking in my eyes. Its not very strong, you can literally not even hear it leaking - so I am not sure if its normal that the CPAP didnt catch it ?


I am using a Prisma SMART APAP and a Airfit n30i mask currently. I cant provide any Oscar data because my CPAP isnt supported by it and I cant install the damn software PrismaTS software. The online prisma journal has almost no info and there its not showing any leaks. The only leaks there are from April. 

Basically, im curious to see if I maybe had a very soft leak for like a minute, would that be enough for the CPAP to catch it?

[RPDM]

I don't know your machine, so the below might be a shot in the dark...

think of the following parameters
- Typically machines register the leaks as liters (of air) per minute
- The leak rate is correlated to the pressure at which the machine operates, higher pressure, more leak.
- The leak rate is dependent on the mask(type) used
- In my OSCAR setting,anything under 24L/min is not considered a leak over the threshold.
- masks / headgear is designed to leak a little bit
- My typical leak rate (at 9cmH2O) is about 18L/min. 

When you have a minor stream of air flowing into you eye, it is probably not enough to register as a leak above the threshold.

Think about this having to blow up a standard party balloon with that little air stream within 1 minute....


Make sens?


(and yes, sometime when my pillow and mask are fighting it out, my leak rate goes up quite a bit.... that air puff can be nice on your face here in the heat of Texas)

[OpalRose]

The leak test function on most machines is ok to test for initial leaks and fit, but as the night wears on, it's very possible that there will be mask movement that can cause small leaks. Also, consider that once relaxed and sleeping, your facial muscles also relax, which could then cause a less than optimal mask fit.

One thing I will say though is if air is hitting your eyes, you will need to correct that, as you will end up with very dry eyes by morning. Be sure you use a nite time eye ointment, and/or an eye mask for protection.

I don't know anything about how your machine records leaks, but it sounds like your leaks are minor. But even with minor leaks, if that happens a good part of the night, your sleep will be disrupted.

[Sleepster]

It all depends on what leak rate statistic your machine is reporting. For example, if it reports the average leak rate for the night, those brief periods of small leaks won't raise the average significantly. Likewise if it's reporting the 90th percentile leak rate.

To properly evaluate your leaks you need to look at your leak rate graph. But you need computer software to do that.

[vrapche031]

Thanks for the replies. Everything you said makes sense. I would really love it if I could get this damn PrismaTS software to work to see how it looks there.