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definition of leaking
#1
I use  a ResMed S9 with nasal pillows.  I have had this for a couple of years but have really struggled to be consistent in use- often get asthma with winter colds so when congested just can't use it and in any event always find it hard to get comfortable as I sleep on my side.  I have really been trying to get my usage up, but my stats confuse me.  AHI average is down to 1-3 for the most part, but with frequent mask leaks (the red face thingy).
I changed to smaller pillows and fiddled a lot with the fit and last night got a green face!  But on Sleepyhead it said the mask was leaking too much (the chart said leakage was above the cutoff 24% of the time.
My questions are:
  • how is leakage defined in Sleepyhead vs my machine's ratings?
  • does it matter much when my AHI seems to be reasonable?
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#2
G'day Gwen. Welcome to Apnea Board.

All masks leak to a certain extent - in fact they are vented to allow your exhaled CO2 to escape. This is called intentional leak. In addition, you can have unintentional leak, which is just what it says. Resmed machines allow an unintentional leak of up to 24 L/minute. Above that limit the air pump can't keep up and the machine can't properly diagnose apneas and hypopneas.

The S9 will give you a red frowny face if you're above the red line for 30% of the night. That means for at least 30% of the time the pump can't supply enough air and the machine can't properly diagnose your events. So a low AHI under these circumstances can be quite misleading. In my view I think the 30% is setting a very low bar, and even at 24% of the time you're losing too much therapy time. (And apparently SleepyHead agrees). SleepyHead defaults to the same 24 L/min leak rate that Resmed uses, but I don't know at what point it gives you the excessive leak warning.

So you really do need to manage the leaks to get a proper level of therapy.

If you're using a pillows mask it's possible the leak is coming through your mouth, in which case you might like to try a chin strap to gently hold your jaw and prevent your mouth falling open. Some members use the "tongue stick" method which will seal the mouth even if it falls open. There is also a rule of thumb which says you should use pillows one size larger than what seems right - but in your case you got better results by going down a size, so that doesn't always work. Smile The other thing you could try is a full face mask, which takes care of mouth leaks and might also help with the winter congestion.

If you post a screen shot from SleepyHead, that will help us see exactly what's going on and give you some better targeted advice.
DeepBreathing
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#3
Hi gwenc,
WELCOME! to the forum.!
Good luck to you with CPAP therapy.
trish6hundred
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#4
Thank you Deep Breathing
I will collect some data over the next few days and then post some screen shots.
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#5
RobySue has some awesome info on interpetation of data with SleepyHead,  see my sig,
Below is only some of the data on leaks and only some of what is there for large leaks.


Quote:Definition of Large Leak
Modern CPAP machines are designed to gracefully cope with a certain amount of excessive leak by blowing additional air into the semi-closed system in order to preserve the desired pressure setting. But even the best of machines cannot accommodate really large amounts of excess leak.
When the excess leaking reaches the point where the machine's manufacturers are concerned that the machine will not be able to properly maintain the therapeutic pressure setting, the leak is defined to be a Large Leak. Different manufacturers define and flag Large Leaks in different ways. Typically, however, Large Leaks are defined in terms of the Total Leak Rate for machines that report Total Leak Rate. ResMed, of course, must define Large Leak in terms of the (excessive) Leak Rate that is reported by their machines.

  • ResMed S9: When the Leak Rate is AT or ABOVE 24 L/min, it is a Large Leak.
(Source: ResScan Interpretation Guide) In ResScan, Large Leaks are flagged by a Red Line drawn at 24 L/min in the (excessive) leak graphs. ResMed S9 users can use the Show Leak Redline option to draw a Red Line at 24 L/min in the Leak Rate graph in SleepyHead 0.9.6. (Earlier versions of SleepyHead do not have this option.)

  • DeVilbiss IntelliPAP: When the Total Leak Rate is AT or ABOVE 95 L/min, it is a Large Leak.
(Source: CLINICAL OVERVIEW: DeVilbiss IntelliPAP® AutoAdjust) In DeVilbiss's software, Large Leaks are flagged by a line drawn at 95 L/min in the (total) leak graphs. DeVilbiss IntelliPAP users can use the Show Leak Redline option to draw a Red Line at 95 L/min in the Leak Rate/Total Leak Rate graph in SleepyHead 0.9.6. (Earlier versions of SleepyHead do not have this option.)

  • Fisher & Paykel Icon: When the Total Leak Rate is AT or ABOVE 60 L/min, it is a Large Leak.
(Source: F&P InfoSmart Spec Sheet) In Fisher & Paykel's InfoSmart software, Large Leaks are flagged by a line drawn at 60 L/min in the (total) leak graphs. DeVilbiss IntelliPAP users can use the Show Leak Redline option to draw a Red Line at 60 L/min in the Leak Rate/Total Leak Rate graph in SleepyHead 0.9.6. (Earlier versions of SleepyHead do not have this option)

  • Philips-Respironics System One: There is no official "line in the sand" for flagging a Large Leak.
(Source: Encore Report Guide) Lots of System One user data posted on the forum indicates the Large Leak line for Total Leak Rate depends on whether the machine is a Series 50 (older) System One or a Series 60 (newer) System One. Lots of user data posted on the forum also indicates that the Large Leak line depends on the pressure used: People using less than 10 cm of pressure see Large Leaks being flagged much earlier than people using pressures greater than 10 cm. Here are some general estimated guidelines for where the undefined Philips Respironics Large Leak line is located:

  • Series 60 System One users may start to see Large Leaks being flagged when the Total Leak Rate reaches 60-70 L/min; if the prescribed pressure setting is below about 8cm, then Large Leaks may be flagged when the Total Leak Rate reaches 50-60 L/min in some circumstances.

  • Series 50 System One users may start to see Large Leaks being flagged when the Total Leak Rate reaches 80-90 L/min; if the prescribed pressure setting is below about 8cm, then Large Leaks may be flagged when the Total Leak Rate reaches 60 L/min in some circumstances.

Official Large Leaks for Philips Respironics System One machines are very difficult to determine with great accuracy in versions of SleepyHead prior to 0.9.6. In version 0.9.6, the Encore-defined Large Leaks are flagged by gray bars in the Events table and as a gray background in the Flow Rate curve. The Official Large Leaks for a System One will NOT be flagged directly on the SleepyHead Leak/Total Leak graph.
If you want to add a Redline to your Leak/Total Leak graphs in SleepyHead, our advice is to look at your own Large Leak flags and figure out where they seem to start. If you don't seem to have very many Official Large Leak, then use the above guidelines as a decent enough starting guess for where your particular Redline should be drawn.
In order to adversely affect the efficacy of your CPAP therapy and the accuracy of the data recorded by your machine, leaks have to be both large enough and long enough. As we've just seen, "Large enough" is easily quantified by the manufacturers. But what is "long enough"?
ResMed is apparently the only major manufacturer that has a user-friendly tool for determining whether the official Large Leaks last long enough to compromise the CPAP therapy: The dreaded Mr. Red Frowny Face shows up on the short version of the Sleep Quality Report when Official (ResMed) Large Leaks make up at least 30% of the night.
Since the other manufacturers are "vague" when it comes to describing how long Large Leaks must last to adversely affect the CPAP therapy, we'll take that ResMed definition as a "working" definition:
If you are in Official Large Leak territory for your machine for at least 30% of the night, then you KNOW you have a Large Leak problem that must be dealt with.

A lot of long-time CPAP users will say that the "30% time in Large Leak territory" is too generous and that Large Leaks will affect your therapy much sooner than that. So this may be a good rule of thumb for you to consider:

  • If you are OFTEN in Official Large Leak territory for 15%-30% of the night, then you PROBABLY have a Large Leak problem that must be dealt with.

  • If you are OFTEN in Official Large Leak territory for 10%-15% of the night, then you MAY have a Large Leak problem that must be dealt with.

  • If you OFTEN have Official Large Leaks that last an hour or more, then you PROBABLY have a Large Leak problem that must be dealt with.


All that said: It's not uncommon for people to simply have a bad night for leaks every now and then. If your leaks are usually decent enough, it can be counter-productive to worry about eliminating the last of the leaks.
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