(02-22-2013, 01:00 PM)jex Wrote: Sleepster, I do not understand the Resmed reference. For the rest do you want to say is that the "real" leak count is found subtracting 35 (in your example) ?
JJJ has a ResMed machine. Those machines report only the unintentional leak rate
, and they set a maximum of 24 L/min (or something like that) as being the acceptable tolerated amount. So when a ResMed user like JJJ sees a leak rate above that he may be thinking that's bad.
Alright, so here's the deal with leak rates. Good CPAP machines have a flow rate meter that measures, well, the flow rate. You need a certain amount of leaking to keep the hose purged of your own exhaled air. That's why you have the exhalation port shooting air at your bed partner. That's what we call the intentional leak rate
. You have to look it up if you want to know what it's supposed to be. Your mask manufacturer makes this information available on the literature that comes with your mask and you can also look it up on their website. The leak rate varies with your pressure setting, so when you go to look it up you see a graph of leak rate versus pressure and you have to read your value off the graph. A good average number is 35 L/min, so let's just say that you looked it up and found out that that's what it is for your pressure and your mask.
Let's say you have a total leak rate (measured by the flow rate meter) of 60 L/min. You have to subtract the intentional leak rate to figure out how much is leaking due to a poorly fitting mask, or a mouth-leak, etc. When you do this you get what's called the unintentional leak rate. If your intentional leak rate is 35 L/min, and you subtract that from 60 L/min, you get an unintentional leak rate of 25 L/min, which is just barely too high. So as long as you keep your total leak rate under 60 L/min, which you are doing, you're in good shape. Which is why your machine is telling you that you are spending 0% time in large leak.
In your profile you list your machine as a PRS1. Not sure if you have a REMstar or a BiPAP. You list your pressure as 10-14 so I'm guessing you have the REMstar Auto CPAP. You should be able to look around in the numerous menu choices within SleepyHead and find a way to have it display total leaks or unintentional leaks. For it to report unintentional leaks correctly it has to know how to figure the intentional leak for your machine's pressure and for your mask type. I'm not sure the author has this completely figured out yet for your machine. I have one of the BiPAP's and I know SleepyHead can't correctly report unintentional leaks for my machine so I just set it to report only the total leak and guesstimate the unintentional leak. I also have EncoreBasic software and it confirms that my unintentional leak is well under control. And like yours, my machine reports 0% time in large leak.