(04-23-2016 04:24 AM)Asjb Wrote: My current settings are Auto-ASV, EPAP 11-15, PS 3-10.
Recently, the IPAP median has been 15-16, and IPAP 95% 18-21.
Should I change any of my settings to improve things? Maybe increase the Max (and Min?) EPAP to clear the remaining obstructive apnoeas and obstructive hyponoeas?
If this data is typical, then increasing Max EPAP is not going to do a thing for you: You never hit max EPAP because there are not enough obstructive events clustered close enough together to warrant increasing EPAP all the way to 15cm
In the close-up snippet of data, for example, the two apneas occur within two minutes of each other (just barely), and the machine responds with a 1 or 2 cm increase in pressure as expected.
When the breathing becomes too shallow near the two scored Hs, we see the ASV part of the algorithm kicking in: Notice how the IPAP very high throughout this sequence of breaths and then drops back down as soon as normal sleep breathing
resumes. The two Hs occur more than 2 minutes apart, so in the machine's view, they're not close enough to warrant an increase in EPAP.
Finally I want to make the following observations about the snippet of zoomed in data:
The whole cluster of 4 events in the zoomed in snippet of data has some earmarks of a short wake or semi-wake period following a possible arousal of some sort: Just before the first UA starts, there is a large inhalation that is NOT a recovery breath. That large inhalation might be evidence of a non-respiratory arousal
At any rate, after an arousal or a mini-wake, the night time respiration pattern has to reestablished, and that sometimes includes a normal "post arousal central" that could be the UA, but your machine's ASV kicks in. There are several very large inhalations at the end of the UA. They could be "recovery breaths" or they could be a sign that the ASV kicking in caused you to wake up or arouse again.
At the end of the OA there are again some large inhalations. Again, they could be recovery breaths or they could be evidence that you still haven't gotten back to sleep ever since the beginning of the arousal that may have occurred before the first UA was scored.
After the end of the large inhalations following the OA and the 1cm increase in EPAP, there's some evidence that you may have fallen asleep very briefly: Although marked as the first of the two Hs, most of the breathing right after the large inhalations is not really that much shallower than your normal sleep breathing (as shown outside the cluster.) It is slower
than your normal sleep breathing, however, and the size of large inhalations around the two apneas has likely reset the running baseline for inhalation size that is used to determine when the airflow into the lungs has dropped enough to warrant scoring a H. My guess is that the ASV has kicked in because of the combination in slowed respiration with the perceived drop in airflow.
The second H looks to be a real hypopnea: The airflow into your lungs has dropped from the previous level and appears (at this scale) to be a bit more ragged. The machine's ASV algorithm continues to force the high IPAP, and at the end of that second H, it appears that you arouse or wake up again for about 30 seconds. Possibly you've noticed the leak that started as you were trying to get back to sleep after the OA. At any rate, after the large inhalations after the end of the second H, two things happen: (1) The leak has been fixed and (2) you transition back into real sleep instead of getting stuck in "sleep-wake-junk."
In other words, this particular cluster of events might include 1-4 events that are not "real" in the sense of being scored on a PSG: If you were awake according to the EEG during parts of this time frame, one or more the events might have been considered "sleep transitional" and not have been scored.
And what might have caused a non-respiratory arousal/wake
before that first UA was scored? Well, the timing is right for a normal post-rem wake. Many people with normal sleep briefly arouse or wake after most rem cycles, but they quickly establish nothing is "wrong" and nothing needs their attention, so they go back to sleep almost immediately. And because the post-rem wake lasted under 5 minutes, they don't remember it in the morning. But in this case, it looks like you had a post rem wake and in the immediate aftermath of that wake, the ASV algorithm kicked in and possibly it or the leak (or both) made a bit harder
for you to quickly get back to a full sleep: Every time you started to drift off, you wound up becoming conscious of either the leak or the sharp change between IPAP and EPAP, which caused another arousal as evidenced by the sequences of large inhalations. Once you fixed the leak and established real sleep, the breathing looked great to the machine and the ASV quit using an IPAP that was 7-10cm above the EPAP.