(02-24-2014, 12:19 AM)Ramen Bear Wrote: I have gathered information on the usage of these masks and I have observed that the lower values AHI seem to correspond with higher values of leakage and vice versa. So far, I have been getting the best result out of Ultra Mirage (M) with a leakage of 6 to 8 L/min but the AHI values range from 30 to 45. I get a smiley face too on the report every morning so it means I had a good fit last night.
Where are those numbers coming from? The S9's LCD each morning??
As others have said, a machine reported AHI in the range of 30-45 indicates that even with the PAP you are still suffering from severe sleep apnea.
If the leakage number of 6-8 L/min is coming from the machine's LCD, that means that for 95% of the time your leak rate is AT or BELOW 6-8 L/min, which is quite acceptable. Chances are the leaks are NOT what is causing your therapy to be ineffective.
So what could be the problem? Well that depends on the breakdown of events. In the detailed sleep quality report, you should see a breakdown of the AHI. In addition to the total AHI, you should see an AI (apnea index) number and a CAI (central apnea index) number. What do those two numbers typically look like?
If the AHI is usually between 30-45 and the CAI is usually under 5, then chances are the pressure setting is not yet optimized and you may need more pressure to prevent the OAs and Hs from occurring. But if the CAI is really high, and in particular if the CAI makes up 50% or more of your events, then it could be that you are in the unlucky 10% of PAPers who are sensitive enough to the pressure to develop a problem with complex sleep apnea or perhaps your correct diagnosis should have been mixed sleep apnea in the first place.
Quote:From what I have extensively researched and thus understand, these two data (leak rate and AHI) should be directly proportional to each other.
Modern machines can and do compensate for reasonable
unintentional leaking by increasing the air flow in order to maintain the desired pressure. As long as a therapeutic pressure is maintained, (most of) the obstructive events should be prevented.
But if the leak rates are excessively large (which yours are not) for a long enough time, then the machine can have trouble tracking the breathing pattern correctly and miss events---in other words, when the leak rate is well above 24 L/min, the machine can fail to detect events and this will make the AHI look lower than it actually is. So for folks with really significant leak problems, it's quite possible for there to be an inversely proportional relationship between leak rate and the machine reported AHI.