Resmed autoset s9 vs. s8 events?

[Hiker]

I've recently started using an s9; had been using an s8.
My AI displays approx .2 on either. However, on the s9 AHI is always reported as the same as AI (e.g., no hyp's); the s8 typically reported AHI in the vicinity of 1.2. Different event criteria, hire effective, or??

[hobbs]

Same here. Five years on an S8 and AHI averaged 4.0. Switched to an S9 and AHI is now averaging 0.3, most consisting of centrals. Better treatment or different way of measuring events, who knows?

[PaulaO2]

It is my understanding that the software innards of the machines changed a lot from the S8s to the S9s and are better able to determine what is what and when. Meaning the S9 would be more accurate.

[zonk]

Better treatment or different way of measuring events, who knows?

Maybe bit of both. Two different algorithm, S8 autoset does not increase pressure above 10 cm H2O when an apnea detected nor respond to hypopnea to avoid falsely responding to central hypopnea

[justMongo]

Better treatment or different way of measuring events, who knows?

Maybe bit of both. Two different algorithm, S8 autoset does not increase pressure above 10 cm H2O when an apnea detected nor respond to hypopnea to avoid falsely responding to central hypopnea

I agree. These machines continue to get smarter with each generation.

[archangle]

I think the difference in readings is in the borderline apnea events. Every machine probably properly records the events where you completely stop breathing for long periods of time. The uncertainty is when you don't stop breathing completely. There's some uncertainty in determining what percent your breathing slows down and how long before you draw the line and say the apnea is over.

The important point is that the difference in AHI numbers may not really mean that much, because it's not the "strong" and long apneas that are being measured differently.