Is There a Secret to Adjusting ASV Pressures?
According to recent research, there is no secret! In a large telemonitoring study of nearly 64,000 ASV users (ResMed brand), the great news was the very high proportion of patients sleeping more than 6 hours per night with the device. The study sought to understand whether the unique pressure setting system known as the “Pressure Support” component had any impact on use. According to their analysis, they found no distinctions either in time on the machine or in AHI improvements. Again, this info is all good news.
The problem with the study is two-fold. It did not assess flow limitation, because the ResMed ASV or ASVAuto device cannot track flow limitation events through remote monitoring (a problem I’ve complained about to ResMed for many years). If you take your device into a DME company, they can download what’s called the Detailed report, and this analysis does show flow limitation data.
Second, there are no outcomes on the study on how patients fared with ASV. Too much of the time, we see research implying hours used is the be-all, end-all of PAP therapy. It’s not, and often not even close.
We need to know how patients were responding to the treatment, particularly as it relates to symptoms of daytime sleepiness or nighttime insomnia. Such treatment gains or lack thereof are often predicated on how well the ASV device resolves flow limitation events. In our own clinical experience with the ResMed ASV and ASVAuto modes, the PS settings are called Max PS and Min PS, and we have seen large decreases in flow limitation events by focusing on the Min PS values, typically in the range of 4 to 6.
Because the study used a wider range of Min PS values from 1 to 6, we suspect those in the lower range would have suffered more sleepiness or insomnia. Future research should investigate the best pressures. Regrettably too many sleep researchers don’t even consider measuring flow limitation events, and therefore, it would be surprising to see interest in how to treat this more subtle aspect of sleep-disordered breathing