Why does the bilevel machine not work for the patient? As mentioned previously, many of the sleep medical specialists are not educating themselves and they do not truly understand how the bilevel machine works.
The ResMed S9 VPAP Auto machine has been superseded by the ResMed S10 AirCurve VPAP machine. I understand that both machine algorithms may be pretty similar. On the blog page Guide to Success using CPAP and Bilevel, I provide the Steps to take to succeed using a sleep apnea machine.
Since writing this blog page, in August 2020, I purchased a more advanced BiPAP or bilevel machine, being ResMed ST-A machine with iVAPS (intelligent volume assured pressure support). This machine was obtained to stop the combination of REM sleep issues, obstructive sleep apnea, insomnia and Awake Bruxism. As with the VPAP Auto bilevel machine; I had a huge leap of faith in buying this machine to overcome these issues. More details are on the blog post Use BiPAP machines with iVAPS and AVAPS for REM sleep issues.
From personal experience, I believe this combination of issues may be an early warning or marker of a diagnosis of REM Sleep Behaviour Disorder (RBD), Parkinson's disease and Dementia and Alzheimer's and other neurodegenerative disorders.