EPR Settings and Flow limits

[Rubicon]

Anyway, can anything be gleaned from this flow curve? It is like this off an on through the night.

Can you be more specific as to where, when and how long this was "off and on"?

[Sleeprider]

You have continued to kill the AHI with the collar, and are currently at 9.4 to 11.4 pressure. For the aerophagia lets see how 8.0 minimum and 10.0 maximum work out. The waxing and waning flow rate looks like a borderline apneic threshold where CO2 is just unstable enough to affect respiratory drive. It is not a problem by itself unless it becomes so unstable that it alternates between hypoventilation and CA, to hyperventilation. I don't see any obvious explanation as to what triggers it for you. It's not a textbook flow rate, but it's yours.

[DJCpap]

I can't wear the collar through the night. I took it off after about an hour last night. Maybe I will try again. I am concerned about the flow curve and how often I woke up last night. It was not restful, so the AHI seems beside the point. Look at this from around 4am.

[DJCpap]

Also, Sleeprider, we tried 9-11.4 and the AHI shot up, so not sure about going to 8. Sort of confused at this point.

[Rubicon]

sleep-wake-junk (SWJ) ...
QAL

That's an interesting acronym.  Where's you pick that up from?

[Rubicon]

The waxing and waning flow rate looks like a borderline apneic threshold where CO2 is just unstable enough to affect respiratory drive.  It is not a problem by itself unless it becomes so unstable that it alternates between hypoventilation and CA, to hyperventilation.  I don't see any obvious explanation as to what triggers it for you.  It's not a textbook flow rate, but it's yours.

To me it looks more like a REM respiratory pattern (specifically phasic REM as stuff like that doesn't happen in tonic REM).

Obviously just a WAG cause don't know if that's actually even sleep.

[StuartC]

I am anything but an expert so I cannot tell you anything conclusive about your chart except for one thing - I think it looks a bit like mine (I have attached one for you to see, plus one of the whole night for context).  So let me explain where I am up to because it might give you and others some ideas.

I get this pattern roughly every 90 minutes even while using (fixed) CPAP.  My flow pattern oscillates much as yours does.  I wear an O2Ring and so I know that my SpO2 drops below 90% and then oscillates more-or-less with a slight lag relative to my flow rate.  Obviously, tidal volume drops when flow rate decreases (e.g. 4:09 to 4:10, 4:11 to 4:12 and 4:13 onward in your graphs).  I cannot see your respiratory rate but mine sometimes slows in the same time period relative to the rest of the night and the combination of low tidal volume and slow respiratory rate lead to low minute vent volume.    

I have recently had a sleep study that showed that, for me, this pattern happens during REM, hence the 90 minute cycle.  I have not got to the bottom of this with my respiratory specialist (long and somewhat frustrating story there), but I suspect it is very telling that the disturbance I see happens during REM, because the sleep tech that I spoke to before my study said something about that being unusual.  I did see a suggestion in the Apneaboard wiki that it may be an early pointer to a significant long-term condition.  

The study also measured CO2 along with everything else.  My CO2 increases when SpO2 drops, which should be obvious, but I needed to confirm that.  Initially, my CO2 was also high even when my SpO2 was normal early in the night when I was in a sleep stage other than REM.  During the sleep study, they tested me on BiPAP and every time they switched me from CPAP to BiPAP, my CO2 dropped - and my SpO2 increased if it was low at the time.  

My sleep study report recommends BiPAP with a target tidal volume and backup rate specified (i.e. ST mode).  I have had a trial of BiPAP since the study and found that I can use that to achieve a target tidal volume, which improves my SpO2 trend through the night.  Unfortunately I know little more than that because I do not know of a way to measure CO2 at home and I could not get data from the machine into OSCAR.  I have returned the trial machine, gone back to CPAP and continue to see the patterns I described above.  My plan is to pursue getting a prescription to purchase a Resmed BiPAP with ST mode.   

So, my two main take-away points from my story above:

1. Monitoring SpO2 helped me understand some consequences of my breathing pattern and to get sent for another sleep study.
   
2. The sleep study confirmed that this happens during REM for me and also allowed BiPAP to be tested and recommended. 
   

I hope this is helpful.

[Rubicon]

I have recently had a sleep study that showed that, for me, this pattern happens during REM, hence the 90 minute cycle.  I have not got to the bottom of this with my respiratory specialist (long and somewhat frustrating story there), but I suspect it is very telling that the disturbance I see happens during REM, because the sleep tech that I spoke to before my study said something about that being unusual.  I did see a suggestion in the Apneaboard wiki that it may be an early pointer to a significant long-term condition.  

Interested in the rest of the story.  What's the secondary condition?  COPD?  Diaphragmatic paralysis? Back of the book neurological condition?

---

COPD? 

Although expiratory limb looks normal, and you can generate good tidal volumes when you really need to.  Central hypoventilation of some sort.

[StuartC]

Interested in the rest of the story.  What's the secondary condition?  COPD?  Diaphragmatic paralysis? Back of the book neurological condition?

Rubicon, I intend posting sometime when I have a few more things sorted - like the right machine and some real data.  I will do it in a different thread though because I certainly do not wish to intrude on this one, which is not mine.

[Rubicon]

OK, looking forward to it!

As we briefly discussed, REM breathing is largely controlled by the diaphragm, so that significant hypoventilation during what certainly appears REM strongly suggests diaphragmatic paralysis. If you can get a hold of a fluoroscope we'll do a sniff test to confirm that.