Not to completely dismiss the possibility that the Resmed's A10 AutoSet algorithm may be unsuitable for your particular flow-signal patterns----
IF your hypopneas are actually obstructive instead of central:
While discussing his sleep study in another thread, tvmangum wrote:It's official. I have just been diagnosed with "Severe OSA/Hypopnea Syndrome." My AHI was 24.10 per hour during 5 hours 56 minutes of sleep. Average O2 sat was 90% with the lowest being 83% during Non-REM sleep and 86% during REM sleep, if I'm reading the report correctly. I had 1 central apnea, 6 obstructive apneas and 136 hypopneas.
Resmed's A10 algorithm will
only respond to hypopneas that
also happen to have wave-shape flattening sitting on the tops of those amplitude-reduced humps or flow signals. That particular design criterion means plenty of hypopneas will intentionally go unchallenged across the patient population. That situation can and does lead to some patients with high residual HI scores on their AutoSet machines. Some of those hypopnea-intensive patients may be experiencing exclusively central hypopneas, others may be experiencing only obstructive hypopneas, and yet others may be experiencing some unknown mix of the two hypopnea types. My understanding is that sleep science is still trying to better understand various hypopnea-intensive or even hypopnea-exclusive phenotypes in the SDB patient population.
But please pay special note to the fact that I said Resmed elects to do that with their algorithm by design. It's not at all a flaw in the algorithm. But that algorithmic situation does leave room for incompatibility with the way that some minority of hypopneic patients present both hypopneic flow signals and lacking precursor-event snore and flow signals. Resmed correctly views that if "obstructive hinting" wave-shape
flattening happens to be sitting on top of a hypopneic wave signal, then it's a safe bet that particular hypopnea was not a central hypopnea. And while the rest of the sleep industry may refer to those particular wave-flattened presentations as "obstructive hypopneas", Resmed at least initially didn't define that as a hypopnea at all (I don't know if they added the signal-flattened or obstructive-hypopnea case to their overall hypopnea definition in recent years). But Resmed relegates that reduced-flow situation as if it were basically the same situation as all the other lesser obstructive "flow limitations"---- also presenting flattened wave shape sitting on top of the flow signal.
In summary, whenever Resmed sees something that looks like a hypopnea, but doesn't have obstructive flattening sitting on top of the wave signal, Resmed very intentionally avoids treating it with pressure, since it might be inherently central in nature (versus obstructive). Resmed thus scores it as a hypopnea and intentionally avoids increasing pressure---to avoid one possible situation of pressure-inducing yet more central hypopneas. That's a cautious statistical guessing game on Resmed's part. In some cases, those are actually patients with obstructive hypopneas who would fare better with a different manufacturer's APAP algorithm----or perhaps even better yet with CPAP. But in plenty of other cases, those really are central hypopneas showing through in elevated residual AHI scores while using the AutoSet's A10 algorithm.
And that last possibility gets us back to wondering if your congenital left-heart insufficiency may be the underlying etiologic cause of your erratically heightened AHI scores. Thus episodic central dysregulation as but
one possible explanation. Good luck in your discussion with the cardiologist.
