Possibly dubious things my sleep doctor said. Opinions needed.

[heropass]

I’m curious: is this Doc board-certified?

[picante]

I’m curious: is this Doc board-certified?

Yes, in family medicine and sleep medicine. FWIW.

[picante]

Your doctor is in that position right now and has offered no solution and has instead attempted to obfuscate the problem and offered an ineffective distraction in the form of a mask change. This does not address the problem.  What should you do?

LOL, I just realized this is a direct question. To me, that is, not the sky or the birds.
Answer: change doctors. Borrow or rent an oxygen concentrator, or whatever you call them. Order one from Mexico or Indonesia. Get the cervical collar and see how much the minute vent and oximetry change.

[Sleeprider]

Your doctor is in that position right now and has offered no solution and has instead attempted to obfuscate the problem and offered an ineffective distraction in the form of a mask change. This does not address the problem.  What should you do?

LOL, I just realized this is a direct question. To me, that is, not the sky or the birds.
Answer: change doctors. Borrow or rent an oxygen concentrator, or whatever you call them. Order one from Mexico or Indonesia. Get the cervical collar and see how much the minute vent and oximetry change.

Only you can decide the course. Your doctor falsely believes he is in control.  Thanks for your thoughtful reply.

[picante]

Last night's oximetry was the worst yet, along with my second-worst AHI (18.81) with bunches of obstructive events. I was on CPAP from 2:ish until 6:ish - you can see that between the discontinuities in the graph when I got up. Funny, the oximetry is worse during CPAP than off it. I've noticed that before.
   

I need some sort of strategy for Wednesday to try and persuade my PCP to prescribe oxygen. She's pretty sharp and rational, but tends to pass the responsibility to the specialists, and the sleep doc is already passing the buck by denying it's a problem.
Would this help?
   

She will want to know what's normal for minute ventilation and/or tidal volume. I have no idea. She may want to know what specs to put in a script for oxygen that feeds into the ResMed. I have no idea.

This many positional/obstructive apneas have been a rarity, as you can see. I lowered to 6 cm pressure on the 17th. My cervical collar should arrive on Tuesday.

I'm whipped. Although gut-aches are better since I stopped Zantac after my overdose Friday. I was following the PAs recommendation that doubling my dose at dinnertime might reduce nighttime reflux. Nope, it just over-alkalized me and made me unable to eat dinner due to a massive gut-ache. I spent yesterday replacing all the nutrients depleted by Zantac (mainly my zinc & B12 were in the tank).

[Sleeprider]

Take your sleep study and highlight where it says "This patient qualifies for oxygen". Combine that with your continued oximetry on CPAP. Tell the doctor if she is unwilling to look after your health, you will find someone that will. Throw the gauntlet. Your health is at risk from repeated and persistent sleep hypoxia. In my opinion the simple approach is best, there really isn't much to think about here. If you want more, try this:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3578679/

There can be some drawbacks to oxygen therapy, but I think the answer to these concerns is that it may resolve the problems from pressure intolerance and mixed complex apnea and is worth a try. You clearly can monitor your SpO2 and track apnea frequency and duration using your current CPAP with an oxygen bleed adapter.

I wrote a wiki on oxygen bleed with CPAP here: http://www.apneaboard.com/wiki/index.php..._with_CPAP

[picante]

I wrote a wiki on oxygen bleed with CPAP here: http://www.apneaboard.com/wiki/index.php..._with_CPAP

Thanks again, Sleeprider, for the practical suggestions. The statement you mentioned was on my nighttime oximetry test back in August. I didn't see any such statement on my sleep studies. I'll look again, though.

Oh my, that was enlightening, doing the calculations: At our altitude, 4200', the O2 level is equivalent to 17.9% due to less pressure, which I rounded to 18%. I interpolated from that ResMed chart to get the L/min at 6 cm pressure:
(3-L/min x 100%O2) + (27-L/min x 18% O2) = 786/30 L/min = 26.2% oxygen
(2-L/min x 100%O2) + (27-L/min x 18% O2) = 686/29 L/min = 23.66% oxygen
(1-L/min x 100%O2) + (27-L/min x 18% O2) = 586/28 L/min = 20.93% oxygen

Is this valid, or is the ResMed delivering 27 liters at 21%?

[Sleeprider]

Oxygen concentration is 20.9% at all altitudes in the atmosphere, although the lower pressure may make it feel like there is less oxygen in the air. This has more to do with partial pressures of oxygen and technical issues with perfusion into the lungs.

Here is some information from the Alaska Air Medical Escort Training Manual http://dhss.alaska.gov/dph/Emergency/Doc...apter3.pdf

Dalton's Law of Partial Pressures means: ... At sea level, the partial pressure of oxygen is 160 mm/Hg, which is 21% of the total atmospheric pressure of 760 mm/Hg. As the atmospheric pressure decreases with an increase in altitude, the partial pressure of oxygen will also decrease, even though it will still remain 21%.

Another way to understand Dalton’s Law is to understand how it affects a person. The transfer of oxygen molecules from the lungs to the bloodstream is dependent on a pressure gradient. Pressure helps the oxygen molecules go across the alveolar membrane. The higher the pressure gradient, the easier the oxygen molecule moves.
As the atmospheric pressure decreases with increasing altitude, the partial pressure of oxygen also decreases. The decreased partial pressure makes it harder for the oxygen molecules to cross the alveolar membrane and get into the bloodstream. The percentage of molecules of oxygen in the air does not change with altitude, but the molecules are more spread out, so fewer are inhaled with each breath. This is compounded by the effect of Boyle’s Law.

In simpler terms, your ability to assimilate oxygen is affected by altitude as a result of the decrease in pressure, and density of all gasses; however the concentration of those gases in the atmosphere do not change. The need for supplemental oxygen increases as altitude iis increase, however in normal individuals this does not usually start below 10,000 feet MSL.  With regard to an oxygen bleed with CPAP, do not adjust the dose calculations in the wiki for altitude or temperature, as the atmospheric concentration is a constant. The Resmed delivers the same CPAP pressure, and the flow-rate (volume) is based on the intentional leak or vent rate of the mask in use, regardless of altitude.

[picante]

From your quote above:
Another way to understand Dalton’s Law is to understand how it affects a person. The transfer of oxygen molecules from the lungs to the bloodstream is dependent on a pressure gradient. Pressure helps the oxygen molecules go across the alveolar membrane. 

That's the new part for me, along with "this is compounded by the effect of Boyle's law", so I went to your source and apparently, this is how it is compounded:

The moisture content of a gas affects the degree of expansion. Body water saturates gases within the body. Wet gas occupies a greater volume than dry gas. Boyle’s Law affects the wet gases within the body even more than it does dry atmospheric gases.
http://dhss.alaska.gov/dph/Emergency/Doc...apter3.pdf 

And that also means that the air I swallow is expanding in my stomach and intestines. And it explains the constipation that accompanies aerophagia, since body water is not as available for lubrication; some is being taken up by the air. Good grief!

In practical terms this what I needed to know:

With regard to an oxygen bleed with CPAP, do not adjust the dose calculations in the wiki for altitude or temperature, as the atmospheric concentration is a constant. The Resmed delivers the same CPAP pressure, and the flow-rate (volume) is based on the intentional leak or vent rate of the mask in use, regardless of altitude.

I think you've got my number, Sleeprider -- I always want to know why! Thanks for your trouble. 

[picante]

however in normal individuals this does not usually start below 10,000 feet MSL.

I used to be a normal individual. When I was out hiking up passes and mountains, it would hit me at around 11,000 feet. Then it was nap time.

When I was tour guiding in Yellowstone, there were often busloads of senior citizens. About a third of them would fall asleep going over an 8,000-foot pass. And then they would profusely apologize for falling asleep while I was giving commentary, LOL.