dsm wrote:In working through this Weinmann info in your post, it actually appears to show a lab test using a seperate FOT signal generator & an isolated detector both in conjuction with a SOMMNOsmart bilevel.
DSM, please take another look at that study's title and
especially the study's objective. That study proposes to evaluate what they term "APAPfot" (a self-adjusting CPAP that is algorithmically based on FOT-determined airway impedance). Specifically, the study evaluates the Weinmann SomnoSmart FOT-based APAP model while allowing for multiple brands of masks (Respironics, Sullivan, Weinmann).
Anyway, Figure 1 shows a diagram of the APAPfot "system" (singular system---not two separate machines). However, that same Figure 1 delineates multiple circuits comprising the Weinmann APAPfot machine under study.
dsm wrote:I don't think there is a way the above technique could be employed in a single machine.
I think if you Google the term "APAPfot" you will discover that those techniques have, indeed, been combined in a single APAP machine---albeit not a popular APAP implementation by any stretch:
http://www.google.com/search?q=APAPfot& ... =firefox-a
-and-
http://scholar.google.com/scholar?q=APA ... =en&tab=ws
Anyway, the Weinmann algorithm is based on complex impedance calculations, and that requires a FOT circuit in the same "machine box" as the rest of the APAPfot system. According to Mr. Google, Weinmann employs a proximal sensor to accomplish those FOT-based complex respiratory impedance calculations---including reactance.