Is major leaks in direct proportion to lower AHI?

[armando.ntg]

Formerly I used a Respironics M Series/ConforFull2 equipment and I couldn´t use softwares like Sleepyhead to monitor therapy. I had access only to AHI and Leaks by the LCD display in the machine itself, always an AHI around 1.5/2, and a Leak rate around 30/40.
Now, I´m been using my new equipment - Airfsense S10 Autoset / Airfit FFM mask - since Oct,14, and, by observing the Sleepyhead charts everyday, I´m noting an apparently direct relationship between lower AHI numbers and major leaks ocurrences. Is that correct? Can I understand that the machine when facing major leaks do not understand other events like OA, H, and so on correctly?
Thanks.

[AlanE]

That's a very real possibility. Air is flowing at a high rate with a major leak with little back pressure (you exhaling).

Due to the method that ResMed uses to determine whether an event is a CA or OA, certain events may show up as an Unexplained Apnea (UA) or nothing at all. ResMed uses FOT (Forced Oscillation Technique). FOT technically is explained as "introducing small oscillations of pressure, about 1cm/h2o peak to peak at 4hz, to the current pressure and using an algorithm on the resulting flow and pressure to measure airway patency."

If there is a major leak those oscillation results may be skewed or not readable. It will also be difficult to detect a proper HA with a high leak. There is little change of flow.

[zonk]

M series leak 30/40 L/m is rather good as the machine report total leak but the same leak rate would be considered high leak on Resmed machines as the machine report unintentional leak. During high level of unintentional leak, AHI value cannot be analysed correctly, also 'unknown apnea' is a sure sign of of high leak