Comparing results from two devices

[Arik]

Hi,

 
I’m using PRISMA 20A CPAP for about two months. Few days ago I run a slip test using the PRISMA 20A and BMC PolyWatch YH-600B PRO at the same time (it is possible to connect the BMC device to the mask via a T type tube).
There was a significant difference in the AHI values read off the two devices as follows:
 
YH-600B readings:
 
AHI 1.8 (Apnea index 1.1, Hypopnea index 0.8).
 
PRISMA 20 A readings:
 
AHI         16/h
oAHI      0/h
cAI          2/h
cAHI       16/h
 
A second night of testing gave similar results.
Please note that the YH-600B includes an integrated SPO2 oximeter sensor while the PRISMA is not.
Can someone explain the difference between the AHI results of the two equipment?
Thanks a lot.
Arik

[Sleeprider]

Arik, your Prisma results show all events were central apnea. You need to compare the pressure that was delivered by both machines, and whether the Prisma is also providing allowed exhale pressure through an exhale pressure relief feature. I can only guess, but it appears at your wide open pressure range, the Prisma probably averaged a higher pressure and may have had pressure differences between inhale/exhale pressures. This can cause central events in some people. Do you have software for either machine?

[Arik]

Hi Sleeprider,

Thanks a lot for your prompt response. The YH-600B is a sleep evaluation device and not a CPAP machine. It looks like the YH-600B is ignoring all central hypopnea events while the Prisma is not. I could not understand the rational behind this but noticed that another vendor (Sefam) is ignoring the central hypopnea events as well.

Arik

[Sleeprider]

I think you should consider getting a proper PSG evaluation rather than rely on these machines intended for home evaluation. It seems likely your apnea is complex or central, and these machines are clearly unable to characterize that, or be used in the justification of an ASV device. BMC is a Chinese company that does not market advanced bilevel therapy, and I would expect not to have expertise in its diagnosis. The diagnosis of central apnea and hypopnea may involve sensors or metrics these manufacturers do not incorporate into the machine. Even with the Prisma, I would want a PSG to confirm central and mixed events.

[Arik]

I completely agree and this is on the road map.
Thanks,
Arik