(03-08-2016 06:03 AM)Asjb Wrote: (last 7 nights) auto-EPAP 11-13, pressure support 5-10.
The increased pressures have reduced my AHI even further (average AHI, excluding these occasional bad nights, of 0.5), even two zero AHIs since I last posted (of a total of 3 ever). But I continue to have the same pattern as for months on ASV in that every 7 to 12 days my numbers escape noticeably - one night last week an AHI of 2.3, & last night 4.6, and the events always come in bunches in a periodic breathing pattern towards the end of the night. But I am sure I was asleep at the time on each occasion so I very much doubt they are sleep-wake junk.
In general my fatigue is much better on ASV compared to CPAP or APAP but it's unchanged I think from now compared to when I had much lower ASV pressures (e.g. fixed EPAP 10, PS 1-7). And yet again, with typical luck, last night was not the once-a-week night when I wear an oximeter (my O2 parameters have always been excellent on ASV). Leaks have been very well controlled during these poor nights and as far as I am aware I have slept very well during these nights.
My current pressure settings are acceptable for comfort, but I was even more comfortable at lower ASV pressures.
If you were me, would you keep on increasing the EPAP and/or PS until these events cease completely? or just ignore them as something that happens sometimes. I can see myself reaching maximum pressures of 25, 26, and upwards, and *still* not abolishing these bunches of events. ...
And why are they happening? I have no idea other than (not sure) they may be during REM sleep (I've never had a sleep-lab study so I have no data as to what I do in REM compared to other sleep stages), or perhaps I am having one of my paralytic events (genetic muscle disorder) during sleep - this would weaken my throat and chest muscles for an hour or so, so perhaps collapsing the airway further. I don't think I am spending much time, if any, on my back or left side (sleeping on my right side was much better than back or left-side during my home diagnostic test).
Although it would of course be good to see what the Pulse Oximeter reports during these clusters of events, I think if you are feeling poorly the day after the occasional nights when these clusters of obstructive apneas/hypopneas occur, this would, all by itself, be a clear indication that these clusters of obstructive events are detrimental to your health.
Pressure Support is the difference between the low EPAP pressure during exhalation and the high IPAP pressure during inhalation.
The pressure level at the peaks of the Mask Pressure waveform are equal to the sum of the EPAP pressure plus the Pressure Support.
The Flow waveform is the machine's estimate of the rate of airflow in our airway, going into our lungs or going out from our lungs. For each breath, the area above the zero axis is the estimated volume of air we have inhaled, and the area below the axis is the estimated volume of air we have exhaled.
While using ASV or ASVAuto therapy modes, during Central events the Flow would remain fairly constant, showing no apneas or hypopneas because the "backup rate" would kick in and Pressure Support would increase strongly. Because the backup respiration rate and the high amount of Pressure Support from the ASV machine are able to keep us breathing nearly our normal amount, central apneas and central hypopneas are prevented.
But during obstructive events, the increased Pressure Support may be unable to maintain our normal airflow.
In the zoomed-in section, all the UA's and H's are clearly obstructive.
During the UA's and H's in the zoomed-in period, we can see these are obstructive because, even though the Pressure Support goes to its maximum, the Flow either does not increase or actually continues to decline, until the Flow eventually jumps higher during our recovery breaths because an arousal has again occurred.
I think it is important that you look at the Flow and Pressure waveforms yourself and understand what these are telling us. Please ask any questions you may have if you are not yet seeing for yourself that these are obstructive apneas and hypopneas which are shown in the zoomed-in period.
Some members who were seeing occasional severe clusters of apneas had been of the firm opinion that they were never sleeping on their back, but to investigate the problem they videotaped themselves during sleep and discovered that, indeed, they were sleeping on their back during these severe episodes. They then took precautions to make sure they would not be able to roll onto their back while sleeping.
As to what you should do now, whether to continue to raise the Max EPAP higher or give up and perhaps lower Max EPAP, my suggestions are:
1. either take precautions to make very sure you are not rolling onto your back while asleep, or
2. if the clusters are not because you have rolled into a bad sleeping position and if, in your judgment, they are detrimental to your long term health, then I suggest to continue increasing the Max EPAP by 1 cm per week, as long as it continues to be "acceptable" for comfort. (You could leave Min EPAP where it is now, if it would be uncomfortable to raise Min EPAP higher.)
By the way, your machine will not accept a Max EPAP setting higher than 15, nor will it raise the IPAP pressure higher than 25.