Event flagging - How it is performed.

[NorthernGuy]

I am interested in how events are flagged.

Are the events flagged in the machine or the software (such as Sleephead) or both individually?

Do all machines calculate and flag the events identically? - Meaning, if same data was applied to all machines, would the scores be identical (or are some machines more or less sensitive in their flagging, resulting in slightly different numbers)?

Are there a certain standard set of rules that are used in flagging the events?

Just curious if everyone on the forum is comparing apples and oranges, or should you only compare your results with your own on the same machine.

Is machine (or software package) X more likely to flag a central event than machine (or software package) Y - from the exact same breathing pattern.

I bring this up, because some of the flagged patterns look pretty subtle visually, but each company's software may recognize them differently. I also seem to get a lot of "trash" events flagged while falling asleep and waking up (ie. I am awake and they are not officially "sleep" apnea), but they are part of the final calculated value sent to my doctor.

[PaytonA]

The machines score the events. I believe that the manufacturers try to stick as closely as they can to the rules for scoring events that the Sleep Association publishes. I also think that the area where one sees the largest differences in how the machine flags events is in their discrimination between Obstructive Apneas and Central Apneas.

Hypopneas are an area where there is a fair amount of wiggle room in the definition for scoring them and the manufacturers can pick their own set of rules within the definition. As soon as I started using my Resmed S9 machine (prior machine was S8 version of the same machine) my hypopnea events reduced substantially. Resmed had altered their rules for scoring hypopneas.

Leak rate is another more obvious source of difference.

Best Regards,

PaytonA