Low events but still oxygen desats - low respiratory rate

[sleepymum81]

Hi 
I am getting a pretty good AHI about 2 weeks into treatment. But I am noticing that I am still getting oxygen desats, and my respiration rate is pretty slow overall. I never get a medium over 12.8. It sits lower than 12 for a decent amount of the night, and this is all I can see that would explain my low oxygen levels. 

I have attached a couple of nights of screenshots of some of the slower periods, I am not sure what this flow rate pattern means. 

My oxygen got as low as 84% during my sleep study despite having an AHI of only 11.4

I am booked in for complex lung function testing in 2 weeks, but am wondering if there is anything I can do to improve my oxygen levels in the mean time.

---

A different night.

[sleepymum81]

And last night, still periods of very slow breathing, anyone can help me with what is causing this? There were zero leaks or flow limits at the time.

[Jay51]

Thank you for posting those charts.  IMO your 12 respiratory rate is not that bad.  Normal is usually around 12 to 20 or can vary even from that.  You have a nice, healthy tidal volume (amount of air you breathe with each breath), so your minute ventilation is close to normal (not bad IMO).  Your charts look fairly clean IMO.  EPR at 3 may be causing some of your central apneas.  Flow limitations look good.  It may take a little more time to adapt to your therapy also and decrease the central apneas - a lot of people have some at the start of therapy, but adapt to them as time goes on.  
You have no clusters of obstructive apneas or hypopneas, which is good.  

Most of the tops of your close ups look round (means good inhalation).  Some are pointy, which is not good.  Squiggly lines is usually snoring.  

Hopefully the lung function test will show more when you take it.  Right now, from this data (I have been through this same thing), it looks like something else may be causing your desaturations rather than your PAP therapy.  Your PAP therapy right now looks adequate to me (not perfect and can improve; but not bad enough to be causing these desats IMO). 

Usually supplemental oxygen is given if you spend greater than 5 minutes under 88% saturation during sleep.  It can be given for other reasons, too.  There are also machine with algorithms that can make you breath more often (can set the rate to higher than 12), but this might be one of the last resorts attempted IMO.  


Please keep us updated as to the results of the lung function test results when you get them.   Any charts that look bad to you, please upload them, too, so we can look at them.

[sleepymum81]

Thank you for your reply Jay51.

I am mostly concerned about the amount of time my respiration is lower than 12 during the night and if there is anything I can do to improve respiration rate as this seems to correlate with the oxygen desats? I guess I am also a bit worried that the machine may actually be making me breath slower (don't know if that's even possible). I have attached last nights screenshots, and made the respiration graph bigger so that you can see what I mean.

Also is it normal for tidal volume, insp/exp time to fluctuate that much? 

I am waking up pretty headachey and tired, despite the low events.

I realize I am probably grasping at straws here, trying to fix anything before my lung function testing results and seeing the respiratory doctor.

I have had a horrible cough, shortness of breath even on rest, dizziness, and a feeling like its hard to breath since June last year. I did have covid a month before that. My blood work has shown consistently high inflammation markers, with no conclusive reason. I had pneumonia a few months ago that required 3 courses of antibiotics to shake. I have only just been referred to a respiratory doctor. I am being treated by my gp for asthma with limited improvements. I did have chronic chest infections as a kid. I don't smoke, or work with chemicals or anything like that, not too old at 41. So it seems sleep apnea is only part of the picture for me. 

I have tried reducing the EPR, but the flow limitations increased. I need to figure out if the centrals or flow limitations are more disruptive to my sleep. Or perhaps the oxygen is the main issue. At this point I would jump at supplemental if that is what is needed, but everything seems to take so long!

[jwest]

Your respiration rate is a function of your respiratory drive, which is driven by CO2 build-up. Pressure support/EPR is what aids ventilation (removal of CO2), so if you want to increase your respiratory drive, then you could try turning down your EPR some or all the way. 12 isn't by itself some dangerous number, and most people actually breathe improperly/take more breaths than they should ideally be taking. No, the machine itself is not making you breathe slower, but the physiological changes that it engenders may be, as mentioned above. It could be playing a role in creating a chemical imbalance.

Just getting to the part where you said you actually did already change your EPR. What was the result? Did you make sure to turn

As mentioned above by the other user, it is quite common for people to develop CA during the first couple weeks of therapy, and they typically subside.

What does your O2 look like? Mind sharing a screenshot here? Does it also monitor movement?

There are sophisticated volume-assured and ASV machines that can provide a backup rate where they essentially ensure a certain number of breaths per minute, and supplemental oxygen is also a thing, but those would be things to discuss with your respiratory specialist/sleep doctor.

My best advice is to work through your case here, consult several experts in the area, and, and I know people don't want to hear something like this, but maybe do an elimination diet/eat extremely strictly/cleanly. Our food is killing us, along with our environment.

[Jay51]

Great points there by jwest.  I just wanted to add, that IMO, your tidal volume and minute vent charts looks pretty consistent over the night (fairly straight across and not too many large spikes up or down).  

jwest gives a great plan to follow.  And it is usually the way the medical system works.  You should get tested by Pulmonologist, etc. 1st to see if any problems there.  Then they may add supplemental oxygen.  And lastly, if all of that fails, there are more advanced machines that can increase your respiratory rate for you.  So you have a lot of options at this point.  The pneumonia could have caused some of the problems, too.

[staceyburke]

Looking through your posts I read your O2 saturation was down to 85 it’s it I could not find any graphs showing your desaturations, would you please post the graph from your Oximeter.

[Lucky7]

Jay, what ARE normal tidal volumes and minute vent? This is an age dependant thing right?

[Jay51]

Tidal Volume Level Estimation Using Respiratory Sounds (hindawi.com)


"The normal tidal volume is around 500 mL in an average healthy adult male and approximately 400 mL in a healthy female." 


Sleep and breathing - Wikipedia


 "A study of 19 healthy adults revealed that the minute ventilation in NREM sleep was 7.18 liters/minute compared to 7.66 liters/minute when awake2. The breathing pattern at rest generally corresponds to about 6-7 liters of air per minute for normal minute ventilation values."

They can vary based on height, weight, and age.  Example:  taller = larger.  Child = less.  Respiratory rate + tidal volume = minute vent.  

Sleepymum81, Stacey brings up a good point.  If you could please post the desaturations from your Oximetry, that would help.