Soon to start CPAP - Question on dehydration

[picante]

Minute vent is more meaningful, but I have no idea what your doctor will look at if anything. The point is your SpO2 is chronically low and you don't tolerate pressures that let us manipulate tidal volume or minute vent.

These charts don't show a relation between my higher pressures and higher minute vent, as far as I can tell. 
I was at 12 cm for the first 2 nights, then dinking around with autoset at max pressures of 14, then 12, then 10-11 until Dec. 17th, when we set it on 6 cm constant so I could titrate up to find the aerophagia threshold.
One of my worst periods of AHI was Dec. 2, when the pressure was hovering up above 13 for a while (I had a max setting of 14 for the first part of the night).
[attachment=9597]

[picante]

Here is the first oximetry report I want to post, from the day before I started on 2L oxygen. I'll post these a bit at a time, as energy permits.
Notice the 4 sections in the graph, separated by the marks indicating the data I excluded. I was up during those times, and the data was junk. 
The order is: CPAP on - CPAP off - CPAP on - CPAP off. The dips are lower for the 2 CPAP sessions than without CPAP, something I observed on several of my nights from Dec. 19th when I got the oximeter to Jan. 11 when I got the oxygen concentrator.
   
This supports what the sleep doc said about these central apneas being generated by going on CPAP. "Everybody has those. They go away."

My dentist didn't think that was accurate. He says I've swapped OAs for CAs because if I've had apnea a long time, my brain has "gotten tired" of telling me to breathe. And now that the OAs are mostly gone, it's still not telling me to breathe, (especially while I'm falling asleep).

[picante]

@Sleeprider, @Bonjour, I've got another curve ball going on.

Interrupting the oximetry focus for a moment because apneas have gone way down while brain fog & grogginess went up. 
Is it usual for low AHIs to co-occur with terrible minute vent and tidal volume? That is my case. I've come to dread low AHIs, in fact.

Please take a look at minute ventilation since Monday. It has been higher since I started O2. Lowering my pressure to below 6 cm did not change that the first 2 nights:
[attachment=9878]          [attachment=9879]          [attachment=9880]          [attachment=9881]
Then I started using the collar again: half the night on Wed. and the whole night on Thurs. AHI is suddenly stellar, oximetry report looks good, but pulse rate was down last night (from average 50-52 to 49) and tidal volume is super low, along with minute vent.

Could this have something to do with the collar? I'm now ordering the softer option, the Caldera Releaf. The one I have is not particularly stiff, but I'm still thinking that it could be pressing on my voicebox enough to increase the constriction there.

Looking back through my daily stats & daily notes, I can see that brain fog + blurry vision correlates with very low minute vent and/or tidal volume, except on nights when I was using CPAP only briefly. So maybe it has nothing to do with the collar and everything to do with my brain.

[Gideon]

@Sleeprider, @Bonjour, I've got another curve ball going on.

Interrupting the oximetry focus for a moment because apneas have gone way down while brain fog & grogginess went up. 
Is it usual for low AHIs to co-occur with terrible minute vent and tidal volume? That is my case. I've come to dread low AHIs, in fact.
Indexes do not but Obstructive Events can, Your Flow Limits are eleveted when you are having whay looks like restful, undisturbed sleep

Please take a look at minute ventilation since Monday. It has been higher since I started O2. Lowering my pressure to below 6 cm did not change that the first 2 nights:
                              
Then I started using the collar again: half the night on Wed. and the whole night on Thurs. AHI is suddenly stellar, oximetry report looks good, but pulse rate was down last night (from average 50-52 to 49) and tidal volume is super low, along with minute vent.
I would not be concerned with a pulse rate drop from 50-52 to 49, the difference is not significant.

Could this have something to do with the collar? I'm now ordering the softer option, the Caldera Releaf. The one I have is not particularly stiff, but I'm still thinking that it could be pressing on my voicebox enough to increase the constriction there.
If the collar became tighter around your neck when you fall asleep it could possibily constrict your neck. This could impact your volumes.  But I will add that I do not know if this is what has happened.  I do know that your Flow Limits significantly increase when you are asleep.

Looking back through my daily stats & daily notes, I can see that brain fog + blurry vision correlates with very low minute vent and/or tidal volume, except on nights when I was using CPAP only briefly. So maybe it has nothing to do with the collar and everything to do with my brain.
Brain fog and blurry vision are symptoms of low oxygen.  Have you checked your O2 through the daytime?

[picante]

@Sleeprider, @Bonjour, I've got another curve ball going on.

Interrupting the oximetry focus for a moment because apneas have gone way down while brain fog & grogginess went up. 
Is it usual for low AHIs to co-occur with terrible minute vent and tidal volume? That is my case. I've come to dread low AHIs, in fact.
Indexes do not but Obstructive Events can, Your Flow Limits are eleveted when you are having whay looks like restful, undisturbed sleep

Could this have something to do with the collar? I'm now ordering the softer option, the Caldera Releaf. The one I have is not particularly stiff, but I'm still thinking that it could be pressing on my voicebox enough to increase the constriction there.
If the collar became tighter around your neck when you fall asleep it could possibily constrict your neck. This could impact your volumes.  But I will add that I do not know if this is what has happened.  I do know that your Flow Limits significantly increase when you are asleep.

Brain fog and blurry vision are symptoms of low oxygen.  Have you checked your O2 through the daytime?

Thanks, Fred, yes, my daytime SpO2 is almost always 98%. I wake up with the groggy/foggy brain & blurry vision. It continued through about 4:00 pm today, when I was doing physical therapy exercises on my back that involve a kind of exhalation using the abs.

I had noticed my flow limitations went way up. They've been lower than that lately.
Also of note: I've had more RERAs since starting the oxygen.

[Sleeprider]

Picante, there is nothing "usual" about your response to therapeutic changes. In this case, there are three changed variables, and I don't know how to isolate them for your complaint on tidal volume and minute vent. Adding oxygen, a soft cervical collar and dropping pressure at the same time could have an effect in combination or singularly. We have to unwind the changes one by one, and I think if you can tolerate it, return to the previous pressure which gave you a couple cm of pressure support. I have not idea how to remove the variable of "my brain" from the equation as that is far beyond my pay grade. As far as the collar, a different style may work better. The objective of a loose supportive fit have not changed, and the idea is to prevent any pressure to the front of the throat. I'm sure your determination will see you through the difficult stuff.

[picante]

Picante, there is nothing "usual" about your response to therapeutic changes.  In this case, there are three changed variables, and I don't know how to isolate them for your complaint on tidal volume and minute vent.  

I can at least tell you it's not related to pressure, since it's been happening sporadically, e.g. Nov. 30 at 12 cm fixed, EPR 3, Dec. 14th at a range of 9-10 cm, Dec. 23rd at 7 cm fixed, EPR 2, Dec. 25 at 6 cm fixed, EPR 2.

Adding oxygen, a soft cervical collar and dropping pressure at the same time could have an effect in combination or singularly.  

I had done the cervical collar a few days and dropped it when I hooked up the oxygen. It was too much gear to deal with right then, and I was getting neck spasms and extra OAs, which confused me. Now I understand better: http://www.apneaboard.com/forums/Thread-...#pid282855

We have to unwind the changes one by one, and I think if you can tolerate it, return to the previous pressure which gave you a couple cm of pressure support. 

Thanks, I'll do that; the EPR of 2 may be critical.

I have not idea how to remove the variable of "my brain" from the equation as that is far beyond my pay grade.  

Everything you do is beyond your pay grade, dear Sleeprider. I think Bonjour Fred's observation about flow limitation is relevant, since flow limitation had gone down so much for me until last night. It may be an indicator that I've got more laryngo-pharyngeal constriction going on from the LPReflux.

Unfortunately, my brain goes into autonomic dysregulation mode from exertion, but I don't know why it would have done that yesterday. I've been resting for many days since the grueling medical encounters last week.

As far as the collar, a different style may work better. The objective of a loose supportive fit have not changed, and the idea is to prevent any pressure to the front of the throat. I'm sure your determination will see you through the difficult stuff.

Thanks for the encouragement, both of you. It's nice to at least have correlated the daytime cognitive problems with the nighttime low minute ventilation and tidal volume. Bonne nuit, will report in tomorrow!

[picante]

Last night was a wash: I had to shut down CPAP at 1:40 due to gut pain from swallowing air. That doesn't tell us anything new; I've already demonstrated that I can swallow air even at the lowest pressures and with my mouth shut. 

Neck spasms and gut pain improved by 7:00 am, and I put everything back on: collar, CPAP, oxygen.

My oximeter battery went dead at 4:10, but I have the usual graph showing that my oximetry looks great these days while on CPAP and much worse while off it.

The post I made on 1-17 above shows you the opposite: Before I started on oxygen, my oximetry looked worse while on CPAP and better off CPAP.

Below is the oximeter report from 1-16 when I managed to do 7h35m on CPAP. I had a little aerophagia, not much. I excluded data from all the times I was up.
   

My Sleepyhead notes:
Overall AHI: 3.16
2:00 Sinus rinse, LPR breathing, put on collar.
Still awake 2:20 to 3:25, trying to get mask comfortable & collar in place.
3:30 Turned down humidity and hose heat: 6 and 80 F. This made my nasal passages barely clear enough to continue CPAP. RERAs are probably from LPR constriction.
A little aerophagia, not much. Mask was too tight up top.

[Sleeprider]

You're mostly doing your own work now, but that SpO2 chart is the best I've seen from you and no problem if that becomes typical.

[picante]

Thanks for the confirmation. I don't have anybody else to compare with, so that's good to know.

On nights when I have too much gut pain to continue CPAP: Is there any harm in just getting a cannula and being on the oxygen by itself?