AHI versus "mean apnea–hypopnea duration" (MAD)

[Henrikc]

Hi,
I am a relatively newly enrolled participant in APAP treatment, and use a Löwenstein Prisma Smart device.
Luckily I found the opportunity on this forum to download the PrismaTS analytical software, and this is really a motivator for me to get the detailed view of the night, rather just an AHI number from the Löwenstein app. 

But is that AHI number enough?

I have found a couple of reports, which state, that the  MAD = mean apnea–hypopnea duration is statistically better related to f.ex. (increased) blood pressure than AHI.
Also, certain surgical procedures have a higher impact on MAD than AHI, and patients who went through the procedure claim more refreshed from their sleep, though AHI remained the same as before the treatment.
Also sPO2 reduction logically must be related to how long you are starved of fresh air....

This leads to my curiosity of how to quantify MAD: What are short, what are extended values, and is it just my improvement during APAP that matters?
(it seems difficult to know what MAD is without APAP, unless one has access to a new polysomnography)

Returning back to the analytical software Prisma TS: 
I can see the duration in seconds of each obstructive apnea/hypopnea and central hypopnea, (typically lasting 10-20 sec.) but not a statistical value for MAD.
Have I missed that?

While a lower quantity of AHI is always better, MAD quality seems not to be mentioned that often?


Please let me hear your suggestions and thoughts.



Sleep tight!

Henrik

PS: If I use a nose mask, and start breathing through my mouth, does the machine then log an apnea event (potentially a long one) but identifiable with high leakage?

[pholynyk]

I'm not familiar with the Lowenstein software, and I haven't run across the term 'mean apnea duration', so I'm mostly guessing here.

A number of people here have said they thought that the duration of their apneas was as important as the AHI, and it sounds like Lowenstein have formalised the concept.

Assuming they are using the 'arithmetic mean' the MAD is fairly easy to calculate, since you have all the event durations. Simply add up all the durations and divide the sum by the number of events.

Since apneas have a minimum duration of 10 seconds, the closer the MAD is to 10, the better. The higher the number, the greater the breathing disturbance.

Obviously, you also want a low AHI, and I'm not sure how you would combine the two to get a single index. OSCAR reports a Total Time in Apnea which can be a useful measure of disturbance.

I don't know if any of that is useful to you.