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Ventilation Decreasing Over Time
#1
Ventilation Decreasing Over Time
I have started to notice that both my respiration rate and tidal volume have been decreasing over time over the 6 months I have been using CPAP. 

My respiration rate has dropped kind of constantly over these 6 months, it started around 14.5 average and now is only 13.5.

My tidal volume was averaging around 460 and then for some reason it dropped on Feb 28th and has been slowly falling since then and now averages around 380 which is 4.5 ml/kg. 

This combination of decreasing RR and TV has lead to a decrease in minute ventilation from what was originally around 6.75 down to around 5.

I have started to leak out mouth a bit more the last little bit and thought maybe the numbers were just being influenced by leak as I have noticed TV and MV are almost always lower than reality if leaks are present but when looking at charts it doesn't seem leaks are that much higher than some other periods when TV and MV were higher. 

Only two things have changed during this time. 1) I flew back from a vacation in Florida on Feb 27th, the exact time my tidal volume dropped overnight. Not sure why that would have had an effect but I did notice some difference in my breathing and nasal congestion due to change in temperature/humidity (much dryer here), what I don't get is why it wouldn't have adjusted back if that was the cause. 2) I have been dieting and treating digestive problems during this time so that might be one of the reasons for decline as I get a bit healthier, I don't believe it is that significant of a weight change though(came down to 185 from around 205).

Anyways I am curious if anyone has seen stuff similar to this and has any thoughts on the matter. I have been dealing with a sleep doctor trying to get a sleep study when this covid issue blows over and they can start doing them again, I am going to bring this to her attention and see what she says. 

   

   
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#2
RE: Ventilation Decreasing Over Time
My MV went down from ~7.5lpm to ~6.75lpm after I went on full time intermittent fasting eating pattern of 17/7.

The day I do a longer fast (> 24 hrs), the MV dips even lower to around 6lpm.

This is due to multiple factors:
1) with weight loss, your MV will trend lower a bit.
2) when your body is running low on glucose/glycogen, metabolism shifts towards FFA (free fatty acid) oxidation from glucose oxidation. The O2 requirement for FFA ox ~ 0.7x of Glucose Ox.
PRS1 Auto & Dreamstation Auto w/ P10 and straight pressure of 7.5cm
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#3
RE: Ventilation Decreasing Over Time
(05-28-2020, 12:12 AM)AshSF Wrote: My MV went down from ~7.5lpm to ~6.75lpm after I went on full time intermittent fasting eating pattern of 17/7.

The day I do a longer fast (> 24 hrs), the MV dips even lower to around 6lpm.

This is due to multiple factors:
1) with weight loss, your MV will trend lower a bit.
2) when your body is running low on glucose/glycogen, metabolism shifts towards FFA (free fatty acid) oxidation from glucose oxidation. The O2 requirement for FFA ox ~ 0.7x of Glucose Ox.

Interesting, the diet I have been following is low FODMAP and mixing in a bit of specific carbohydrate diet as well so much lower carb/sugar intake and my metabolism would definitely be shifting towards FFA. I didn't start dieting until around April 10th though so that doesn't really explain all of this though. 

I find it really crazy how my MV dropped from 7.5 average to 5.75 overnight after returning from Florida. I wonder if that is just due to lower humidity here cause I can't think of much else that it could be. 

Leaks definitely seem to affect the numbers too although in a recent night with minimal leak I had MV of 5.13. I bought a FFM that I should get in the next few days so it will be interesting to see how that affects things and sleep quality.
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#4
RE: Ventilation Decreasing Over Time
Used the new FFM for 2nd night now. Some minor leaks but not big enough to influence data significantly. MV is slightly higher I believe due to fewer leaks but still only 5.5 last night. 


   
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#5
RE: Ventilation Decreasing Over Time
Ventilation has been slowly increasing now and is back close to what it used to be. ~460 TV and 6.6 MV the last little while.

   

I have also been starting to feel noticeably better over this time. Not 100% better but able to finally work 40+ hours a week and still have energy to do some other things. A number of other symptoms such as IBS, nasal congestion, reflux have also improved.

It isn't clear what has caused this improvement and it could potentially be some combination of three items.

1) Full face mask. Has made my leaks non existent and perhaps maybe improved sleep quality although I have been having higher apnea, higher flow limitation and sleep data still looks to be interrupted. I haven't recorded myself in a while to see how that has changed or how it looks like I sleep when wearing FFM. I don't think this is the one that made the change but perhaps has been a factor.

2) During elimination diets it seemed like perhaps dairy (protein not lactose) was a trigger. I have now been dairy free most of this time. My other symptoms such as nasal congestion, IBS, reflux etc fit a cows milk allergy/sensitivity so I feel this may be a significant cause of improvement.

3) During elimination diets my results were fluctuating and didn't know why. Looking back I think it was because I was still consuming lactose free dairy but not knowing why lead to being tested for SIBO (small intestine bacterial overgrowth) which came back as slightly positive. I was on antimicrobial herbal treatment (candibactin and NAC) which are made up of stuff like oil of oregano that are known for helping treat digestive issues and also other infections and NAC is known to help with chronic bronchitis/breathing stuff. I think this might have helped but again SIBO is usually considered a symptom more so than a cause although once in place it can be the cause of significant symptoms. Improvement could be due to these antimicrobials either treating SIBO or something else.

Unfortunately I am not sure what the exact cause of improvement is. I am off the antimicrobials now but will be sticking to FFM and dairy free diet to see what happens going forward. It sort of feels like I have plateaued on improvement but I may still be improving very slowly. Anyways just some curious findings that I thought might interest others. These past couple months have been a life changer so hopefully will continue to see improvement and can move on from these couple years of health issues.
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#6
RE: Ventilation Decreasing Over Time
Did an overnight home sleep study (my own version with CPAP, oximeter and video recording) for first time since the end of June.

Pleasant surprise was that my average SPO2 was 95% which is the highest it has been in the 19 overnight recordings I have performed over the past 7 months. My last recording was done on June 24th after having already used FFM for 24 days and it was only 93.3%, almost all of my previous recordings were in 92.5%-93.7% range (lower end of range if not using CPAP, higher end of range if using CPAP). Proof that the FFM didn't fix my breathing issues right away, if FFM happens to be a reason for improvement it would have to be a slow gradual improvement I guess due to slightly improved sleep quality over time helping body recover from the other issues that had developed. I am curious to do a test without CPAP now to see how it compares, in the past there was minor difference maybe 0.5-1% SPO2 lower on a whole, no obvious desaturations etc.

I was curious so did an hour long recording this morning while awake and result was 95.2% which was also the highest of now 4 awake recordings (94.7% on June 24th being most recent test). So not as much fluctuation here but still minor improvement.

Sleep quality seemed better. Still getting some odd movements and sleep still seems fragmented but some noticeable improvement over past recordings.

OSCAR data was a bit lower ventilation (440 TV and 5.75 MV) than recent days and AHI was 2.3, 95% flow limitation of 0.05. Kind of a typical night for the most part. One of the curiosities of this improvement stage is how my apnea and flow limitation has been worse but I believe that is just due to the full face mask. You can see this in overview data (started using FFM May 30) but also how leak issue was resolved which I believe is more beneficial (not to mention the FFM is far quieter and no annoying venting, I will never go back to a nasal mask unless they come out with a better version (I have tried P10, N20, P30i and N30i). One other thing I noted is that the higher amount of flow limitation appeared to improve with APAP so I reverted from 9 CPAP to 9 min APAP and on a typical night it increases to 14-15 now. With the nasal only masks it only ever fluctuated up to 11 or 12 but again this would be due to higher apnea/flow limitation.

Anyways just some interesting findings and documenting things to see how they might change over this next while.

   
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#7
RE: Ventilation Decreasing Over Time
Geer1

Interesting graph it looks like your CA's have morphed into Hypopnoeas recently with the FFM does that indicate a need for a bit more pressure due to the extra volume of the mask we also see an improved leak rate.

Thanks for posting
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#8
RE: Ventilation Decreasing Over Time
Lots of my CA's (probably most) and some of the OA's are post arousal.

Now they sometimes occur in strings of hypopneas/apneas and it increases pressure through APAP. I have woken up a couple times after real OAs and glad I dont have that often, I also get some strings of bad flow limitations that I never got with the nasal mask. I think it is all to do with FFM and saw similar with my grandfather's data who never could get the FFM to work because apnea was too high with it.

I think the machine does about all I can expect it to do. Curious if a Vauto may potentially help but I will wait on that. If I ever get home (working on the road right now) I should be able to get a sleep/titration study and answer some of these questions.

I'll try to remember to post a few screen shots later of apnea/flow limitation for those curious.
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#9
RE: Ventilation Decreasing Over Time
Here is an example of some hypopneas that occurred together with last one causing an arousal. Can see the clearly flow limited breaths getting worse and worse, this is something that never happened when I used nasal masks so has something to do with FFM. I don't think it occurs often enough to be considered a significant issue though.

   
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#10
RE: Ventilation Decreasing Over Time
Great observations and improvement!

Which FFM are you using? I'd love to find one that works for me.
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