Long time CPAP user still fatigued

[enigmatic]

I can very clearly see (and you can too on my charts posted) my SpO2 drops in REM as does tidal volume.
Pretty sure I've seen literature support this as well.

Hmm, that's strange. As always, I could have it wrong, but I distinctly remember that oxygen consumption during REM is hugely increased, and breathing increases accordingly (i.e. both tidal volume and breathing rate increase; metabolism is also hugely increased, which is the basis for the increased oxygen intake). 

Would that perhaps suggest that you have some kind of a problem responding correctly to the extra needs of the body for increased oxygen during REM sleep? On the other hand, are you sure it is really REM sleep? Purely off the cuff, I seem to recall you mentioned using some other measure to represent sleep stages - or was that just a matter of data importation mechanism? How are you measuring sleep stage?

I guess we are both right. Looking closer, I guess the relationship varies depending on severity of OSA, "Patients with mild and moderate OSAS showed no significant difference in oxygen saturation during REM and NREM sleep. In the case of patients with severe OSAS, the average oxygen saturation was lower during REM than NREM sleep. " Maybe not too scientific, but when I look at my charts like attached I can mostly see more erratic behavior and desaturation in oxygen and tidal volume drops during REM (state 2 from apple watch) even though I'm not really severe by AHI metrics. I've found the watch to be fairly accurate with my sleep study results (wore both) and even looking over my eye REM time frames on cameras they seem to be in sync.

Problem is with the doctors is most non specialists will admit they don't know so they send you to other specialists that don't really know or maybe care to give you the level of detail (so you get to try/waste time on this or try that based on wags) you want. And it's not like I have a choice of 50 sleep drs. I'm afraid that unless I go to some specialized university or get admitted to ER for some type of severe problem, the choices are slim pickings. It's not a money issue either, heck, I'd pay to get solid answers with proof. Even the titration methodologies are not standardized much, and you get one night and one sample to have it done. It's just not practical. So here I am with you other outliers trying to make sense of it.

[enigmatic]

It is a serious misconception to conflate "Tidal Volume" in the context of forced ventilation with tidal volume in the context of non-forced ventilation. The two are totally different metrics.

fair enough. I'd like to find more research on tidal volume in the context of sleep and tidal volume measurements of apnea machine. I would think there is some
type of 'normal' tidal volume and range associated with nighttime and non forced ventilation. That's the metric that stands out to me. But I accept it may be more complicated than that.

Regarding CO2 measurement during the day: it should be obvious that measuring blood CO2 during the day has absolutely nothing whatsoever to do with hypoventilation or hyperventilation during sleep. If your doctor is trying to suggest otherwise, then he is very clearly guilty of professional misconduct. My advice is to look for a more competent and/or honest doctor.

I do wonder about this. Because if what you are saying is true why would drs. send you to get metabolic panels to look for these things? If it varied that much between day and night, you would need to go get your CO2 test at nighttime in a hospital ?- doesn't make sense to me. I would think the excess carbon dioxide would accumulate over time and shift the net CO2 level outside normal ranges. Not saying you are wrong, because I don't know for a fact and want to know. But can you show some kind of link that states this as fact? I.e. CO2 test for hypoventilation during sleep must be performed at night in a lab setting? I found this...

"Obese adults with sleep-disordered breathing and increased blood carbon dioxide levels during the day are likely to have obesity hypoventilation syndrome (OHS)"
 If serum bicarbonate is below 27 mmol/L, it is not necessary to conduct further testing as the patient is unlikely to have OHS.

If I had any type of hypoventilation, I would suspect it would be the obesity related type.
As far as I know that test is conducted in a normal blood work lab in the daytime. Is there a different classification of hypoventilation between wake and sleep?
That quote seems to contradict your comment about no relation between hypoventilation at sleep and CO2 levels in the day.

I seem to recall having come across sensor devices that operate on the same principle as SPO2 devices (i.e. LED light transmitted through blood vessels under the skin), but measuring CO2 instead of O2. It could possibly be a false memory, but I think they exist. 

Now this would be great. But I could not even find a simple example of this anywhere. Not even patent search. Blood Oxygen is fairly easy to send a light signal through our skin and get a distinct reflection because of the light/dark difference in red tone corresponding to saturation. There are other factors like signal strength and wavelength safety etc.. I also read that a pulse oximeter cannot detect a difference between CO2 and SPO2 because the CO2 molecules mimic SPO2. Seems like they would measure CO2 via gaseous streams with capnography in practice. I just don't see how they can get accurate CO2 measurements with pulse oximetry in practice.

[enigmatic]

ignore. can't delete

[Bhante]

I do wonder about this. Because if what you are saying is true why would drs. send you to get metabolic panels to look for these things? If it varied that much between day and night, you would need to go get your CO2 test at nighttime in a hospital ?- doesn't make sense to me. I would think the excess carbon dioxide would accumulate over time and shift the net CO2 level outside normal ranges. 

...

If I had any type of hypoventilation, I would suspect it would be the obesity related type.
As far as I know that test is conducted in a normal blood work lab in the daytime. Is there a different classification of hypoventilation between wake and sleep?
That quote seems to contradict your comment about no relation between hypoventilation at sleep and CO2 levels in the day.

Any tests the doctor orders he gets paid for. Profit in his pocket. That is what Western medicine is all about. He doesn't care if it is useless, he still gets richer.
CO2 won't hang around in the body. I don't know what the half life is for CO2 in the blood but probably exremely short because CO2 is a very simple molecule to metabolise. If the half life wasn't very short, SPCO2 devices like SPO2 devices wouldn't exist.
Well, as far I can understand, central apnea and hypoventilation during sleep are in the same ballpark. Hypoventilation can potentially be for different reasons. If you wear a mask that absorbs CO2 from the air before you breath it in, that will cause hypoventilation. If you have weak nerve transmission to the diaphragm that can cause hypoventilation. Potentially there could be all kinds of obscure interference in the breathing control mechanism that could cause hypoventilation. 
By definition on this website, the emphasis is on sleep-related hypoventilation, which by definition occurs during sleep and not during non-sleep. But obviously there is no reason in principle why somebody with 24-hour-long hypoventilation should not independently from the daytime hypoventilation also have sleep apnea and consult the blog in connection to that. However you clearly said that daytime hypoventilation was tested (daytime CO2 levels) was tested and shown to be absent. Therefore it seems clear to me that if you have hypoventilation problems causing your sleep problems there is no reason to expect CO2 deficit during the day coming from daytime hypoventilation - that is unless you are also sleeping during the day. If you have waking time hypoventilation causing increased CO2 levels you must have symptoms of daytime hypoventilation that go with that. As far as I can see you haven't mentioned any such symptoms.
Is daytime hypoventilation in a different class to sleep hypoventilation? Yes of course it is. In the latter case there is a clear causal link between the presence or absence of sleep at a given moment, and hypoventilation at that moment - the same as obstructive sleep apnea. In the former case that causal link with sleep is wholly absent. That necessarily means that the causes of the hypoventilation are completely different, and that the symptoms are completely different.

[Jay51]

You guys are both very smart (Enigmatic and Bhante).  I was diagnosed for hypoventilation by an overnight home sleep study that did capnography.  The little device had a nasal cannula - that was how my sleeping CO2% (ETco2) was tested.  PCP ordered it. 

An ABG (during the day) or basically anytime, can give a snapshot of the % of Co2 in the blood. The problem is the technician needs to draw it and run it through the machine (needs to be done at a lab I guess or hospital).  Could be done during a polysomnography.

And just for reference, my daytime co2 levels were normal (actually, my o2 was slightly elevated during the day - with slightly lower than normal % of co2 in my blood).  But at night during sleep, that was when I hypoventilated.  But on the flip side, a member here who hypoventilates, has both spo2 drops during the day (with increased co2 levels) and during sleep (along with a medical history that would support the increased daytime co2 levels).  So I guess it can varies.

[enigmatic]

You guys are both very smart (Enigmatic and Bhante).  I was diagnosed for hypoventilation by an overnight home sleep study that did capnography.  The little device had a nasal cannula - that was how my sleeping CO2% (ETco2) was tested.  PCP ordered it. 

An ABG (during the day) or basically anytime, can give a snapshot of the % of Co2 in the blood. The problem is the technician needs to draw it and run it through the machine (needs to be done at a lab I guess or hospital).  Could be done during a polysomnography.

And just for reference, my daytime co2 levels were normal (actually, my o2 was slightly elevated during the day - with slightly lower than normal % of co2 in my blood).  But at night during sleep, that was when I hypoventilated.  But on the flip side, a member here who hypoventilates, has both spo2 drops during the day (with increased co2 levels) and during sleep (along with a medical history that would support the increased daytime co2 levels).  So I guess it can varies.

Very good info (Bhante too). Now@Jay51 these are they types of tests I was looking at. I can't understand why my sleep dr. doesn't tell me to order or run capnography and or ABG tests, instead wants to 'try' asv. I get the profit incentive, but almost every sleep lab/pulmnologist I look up seems to have the same mode -- routine AHI test and go home feeling bad try these pills or go see psychologist or other non specialist, new titration, repeat....
If I could find this stuff on the internet, surely my dr. must be aware. So frustrating, it's up to us to learn these things.

My one clue is SPO2 is almost always >90 (much better in day), which is a good sign along with the daytime CO2 bloodwork. I wonder, have you tried looking at OSCAR signals to find characteristics of your hypoventilation (along with significant SPO2 desaturations to support). I'm happy to help process the signals in any way.

Also, did you ever determine the type/cause of hypoventilation (obesity, neurological, etc?) and if so, how did/you they determine.

Had 0 OSA and about 9 CA last night 9 hours, 10.8-15cmH2o and EPR 2, and seriously tired this morning. When I observed overnight cameras the CAs almost always occurred with turning over, and scratching face and sleep lab said 0 CA. I actually felt better yesterday morning, no machine at all. I am seriously thinking to try and pay for the ASV out of desperation. I should add he said customers complain a lot more about tolerating AVAPS and that ASV will adjust tidal vol (though I get others here saying not really it just rolls along and stabilizes recent tv).

ps I don't always do SPO2, because 1) it is annoying and puts a lot of pressure on finger for 10 hours 2) They have been farily consistent
   

[Jay51]

Great questions Enigmatic.  On my polysomnography and 4 home capnography tests that I have taken, I have hypoventilated on all of them.  My respiratory rate low was around 5 or 6 for the entire night.  My average is higher than that though.  My tidal volume was very low on all 5 at times.  On my poly, they recorded a "snapshot" of everything every 15 minutes when I was asleep.  A few of my tidal volumes were in the double digits (i.e. - 50, 60, 75, etc.).  Really low.  The capnography simply measures ETco2.  Normal is between 35 and 45.  Above 45 is hypoventilating (exhaling too large a % of Co2).  Below 35 is hyperventilating (exhaling too small a % of Co2).  

We still do not know the cause of my hypoventilation.  I am 6'2 and around 160 or so (but still was diagnosed with it).  In all the research I have done, the most common form is OHS.  Next is a congenital (child's) central hypoventilation syndrome.  Then there are those like me with an unknown cause.  

I have used OSCAR on my S9 Adapt ASV for naps many times (I use the Evo at night).  I can tell right when I fall asleep because my tidal volume and respiratory rate drop a little bit (and the ASV kicks my IPAP pressure (PS) up to the max).  The problem with ASV and hypoventilation is that the longer a hypoventilator sleeps, the lower the tidal volume (and possibly even respiratory rate) can possibly get because the ASV is constantly recalculating based on the person's spontaneous breathing effort.  Your charts may look like a downhill slope.  But not necessarily if your spontaneous breathing is good enough.  Your spontaneous breathing doesn't look really bad IMO, just some lower than normal tidal volumes.   I doubt if I am getting to REM sleep during these ASV naps.  My worst low in respiratory rate and tidal volume most likely occur in REM I think.  Maybe not.  

In your OSCAR charts, look for anything unusual when your tidal volume/ and or respiratory rate drops low.  Your SPO2 numbers during sleep are ok (like StuartC also noted).  I have seen drops into the low 90's, but nothing lower than that if my memory serves me correct.  That is a huge positive.  

AVAPS or IVAPS can be more difficult to tolerate than ASV.  He is correct there.  On a VAPS machine, there are many different setting.  Get them right and probably good sleep.  A few wrong could make for problems.  With ASV, just set a low enough min and max for both EPAP and PS, and it will auto titrate for you basically.  I have used both and there is definitely a learning curve to sleeping with both.  I don't want to influence you either way on whether you get an ASV or not.  Your decision.  I tough one IMO.  Keep asking questions and doing research until your mind is made up.   If anyone else has any opinion on whether Enigmatic should get ASV, please post.

[enigmatic]

@Jay51. Lots of great info and comments -- very grateful. You certainly don't sound obese to me.

Looks like I will be starting ASV tonight (and I have runny nose and cold... sigh). At least this time, they said they
will monitor and adjust titration remotely (fingers crossed). I'll keep you all posted.

[enigmatic]

1st night ASV.

quantitatively: numbers/events look really good, no more (oscar) CAs at all. I can even see continuous breathing through watch wakeup states, unlike before (osccar typically reported CAs and there were flat lines sandwiched by what looked like sleep junk in those event periods -- I've always assumed those were false positives, now not so sure).
Tidal Volume median Higher (could just be skewed by more than normal wakeup periods). It targets and tracks minute ventilation and directly affects TV, I guess.

They also had me user large nasal pillow (from small I was used to). 
The bad:
Lot of either leaks or hissing noise (hard to tell if hissing was exhale port or leak), which is why I switched to small over time, but they showed me large does seal nasal hole better visibly
(can see by looking in mirror at seal filling up nostril, small has tiny visible gap ring between pillow and nostril boundaries, whereas large fills it like an expanded balloon or wedge).
Maybe the small was limiting CO2 exhale... they never really say you can't mix small with med headband but...
Not sure if they did any adjustment, but had that hard hurdle of breathing against strong air both in and out (not smooth), like in the early days/years.
New weird phenomenon, woke up several times and noticed it didn't want to always let me exhale fully like I desired, it's like the algo was forcing me
to breath in again, before I felt fully done. It's like I had to keep overriding, fighting, and training the algo to allow me to exhale longer. Took a while to either adapt to that or they might have adjusted remotely.
All these contributed to many wakeups (can be seen on choppy watch sleep state as well).

Felt decent at wakeup, but am feeling a bit tired now. Need to give it some time. And will let them make adjustments remotely at onset.
Any recommendations/thoughts are appreciated here as well.

[Jay51]

Looks better.  Higher tidal volume.  I had the same challenges you are having the 1st couple of times I used my ASV.  In time, I was able to completely sleep through naps.  If you can learn to sleep continuously with it, the charts look clean IMO.  

I guess you could either reduce PS max a little bit or reduce the Max IPAP a little to see if you can sleep more continuously without waking up.  But your charts might look worse.  Balancing act.  Best strategy may be to keep things like they are and try to adapt to it.  Your call Enigmatic.  

Leaks can be a problem with the pressure swinging up and down and up and down, etc.  Can try readjusting mask if you are awake and the pressure is high (vs. adjusting mask when you lay down to go to sleep - pressure will be much lower).