(11-20-2013 09:26 PM)Tez62 Wrote: Donna, the most important figure is your AHI, the lower the better but it needs to be below 5, leaks are important too they should be below 24.
That leak advice is misleading. Donna is using a PR System One machine that reports total leak
not just the excess leak for her mask. And for most masks at most pressures, the expected leak rate is greater than 24 L/min. Hence it is very, very rare for a PR System One user to see leak rates that stay under 24 L/min.
Moreover, unlike the Resmed machines, the PR machines do not have a well defined "large leak line". However, from what I've seen on other boards from PR System One users Encore reports, the System One machines when start triggering is somewhat dependent on the pressure setting used. At pressures in the 10-12 cm range (like what Donna is using), Large Leaks tend to get flagged once the total leak
gets up somewhere around 85-95 L/min. But leaks can be below that official Large Leak threshold and still be well above the expected leak rate of the mask and these large, but not "Official Large Leaks", are frequently a source of sleep disturbance in PR System One users.
There are three kinds of leaks to keep in mind when you are looking at your data in Sleepy Head.
1) First, the intentional leak rate
is the rate that is built into the design of the mask and it keeps you from rebreathing your own CO2. This is the air that you can feel coming out of the exhaust vent holes if you put your hand near them. This is a good
form of leak. But the intentional leak rate varies from mask to mask AND it also depends on what pressure you are using. There should be a graph or a table in your Wisp user manual that gives the intentional or expected leak rate at a variety of pressures. I've been unable to find the user manual on line, but similar sized masks typically have expected leak rates for 10-12 cm of pressure at anywhere between 25 and 35 L/min.
2) Next, there are unintentional leaks
. These are any leaks over and beyond the intentional leak rate built into to mask. Unintentional leaks are the BAD leaks. The Resmed machines only report unintentional leaks and Resmed draws a bright Red Line at 24 L/min as the dividing line between unintentional leaks that are large enough to create problems and unintentional leaks that are small enough for the machine to compensate for. Hence some Resmed users think any leaks over 24 L/min as "bad news."
4) The third kind of leaks are total leaks
. The total leak rate
is just the sum of the intentional and unintentional leak rates. In other words:
Total leak rate = Intentional (good) leak rate + unintentional (bad) leak rate
The System One machine you are using reports the total leak rate
. Because the total leak rate includes the intentional leak rate for your mask, your total leak rate will NEVER be 0.0 L/min. If you have NO bad
leaks, your total leak rate will be equal to your mask's intentional leak rate at your particular pressure reading (plus or minus about 5 L/min "margin of error"---there is some varience in the actual intentional leak rate for a mask versus the calculated leak rate for the mask.
In other words, a perfect leak line in Sleepy Head would be a relatively flat line near your mask's intentional leak rate at your pressure. In practice, you're not likely to see a perfect leak line. In practice, your leaks are going to bounce around a bit and Sleepy Head may make the bounces look larger than they really are. A decent starting guideline for judging your leak line (for now) is to add about 25 L/min to your mask's intentional leak rate at your pressure, and then use that number as a rough guide of when the leaks are approaching large leak territory. For example, if your mask's intentional leak rate at 10 cm of pressure is about 30 L/min, then try to keep your leaks under 30+ 25 = 55 L/min.