Clusters of apnea events with otherwise normal breathing

[leptic]

Hi -

I recently joined and posted an intro in this thread. I am not a healthcare professional and am not an expert on sleep, but I work in neuroscience and physiology research and have access to monitoring equipment. I’m waiting for results from an overnight test I did last week with a sleep clinic, but in the meantime I have been having some ‘fun’ monitoring my expired O2 and CO2 during the night.

The observations are intriguing (to me at least), and I would be very interested if anyone who has more expertise could comment. Basically I have long periods of normal breathing, with clusters of the regular apneas as shown in the graphs below:



Please note that, although the ‘rate’ of apneas during these clusters corresponds to around 80/hour, the clusters don’t actually last an hour so my AHI is probably nowhere near 80. The graph below zooms in to show several regular breaths followed by an apnea lasting around 27 seconds. Please also note that the O2 value shown here is *not* saturation, but rather the level of O2 in exhaled air (which is related to O2 sat but not the same thing). It's only a coincidence that the O2 partial pressure drops to 80mmHg - that's not the same thing as an O2 sat of 80%, although it is abnormally low.



The timing of the clusters looks suspiciously like they arise when REM sleep would normally occur; as I noted in my other post I had a sleep study years ago that indicated narcolepsy, in part because I entered REM sleep very rapidly after turning out the lights (and in part because I entered REM rapidly and repeatedly during daytime sleep tests the next day). That test was done when I was young and thin , and did not indicate any sleep apnea issues.

This image shows the general timing of the apnea clusters:



This one shows an interval of normal breathing:



(*note: the fact that the CO2 trace does not go down to zero indicates there is a small amount of rebreathing from dead space in my improvised mask; the setup is normally used with medical air blowing in through one-way valves but I wasn’t going to drag an h-size cylinder home. I modified the mask some to minimize dead space, but would probably use a mouthpiece to do this for real. Should not affect breathing rate or values significantly.)

I am wondering if anyone can comment on whether clusters of apnea like this are typical, and (while I wait for my doc’s report), what the significance might be.

[leptic]

I will just add that my subjective daytime symptoms are very bad - extreme sleepiness, depression-like symptoms, and cognitive issues. These have progressively worsened, along with my wife's complaints about my snoring, over the last three years. If CPAP will help with these it will be truly life-changing.

[leptic]

Hmm. Must remember: Google is my friend.

There is at least one paper (ok it's actually a commentary published in 2011) on something called REM-related OSA.

The authors speculate on whether REM-related OSA may or may have disproportionately serious consequences, due to its impact on REM sleep. They also note there is a risk that the global AHI in such patients might be too low for a physician to prescribe CPAP, although it might nonetheless be beneficial.

I should look for some more current articles, but I suppose this is why we need to self-educate.

[grayghost4]

I have had three in lab sleep tests (long story why) all three test show an AHI of around 5 ..and they did not think I would benefit from a CPAP.... I got one anyway (from craigslist a bipap 760).

When I finally got into rem sleep the ahi went up and the pressure went up.

It has taken me two years and the help of many people here to get a good nights sleep.

I now use an S9 adapt ASV, and the pressure goes up to 25 for very brief periods of REM sleep, and it controls the apneas ... AHI is usually 0.0 and I no longer get up three or four times a night to go to the bathroom.

[palerider]

Hmm. Must remember: Google is my friend.

There is at least one paper (ok it's actually a commentary published in 2011) on something called REM-related OSA.

worsening of OSA, and emergent CSA in REM is not uncommon.

[leptic]

and I no longer get up three or four times a night to go to the bathroom.

Thanks for the posts from you and others - the nighttime bathroom thing is another big one. I am often up 3-4 (or more) times in a night to pee. This was another thing that drove my wife absolutely crazy.

[Morchella]

I'm pretty new myself so I have no expert commentary for you, but I can definitely say that you are not the only person with that pattern of long periods of normal breathing and then sudden clusters of frequent apneas. Check out this beauty of a night:



In my case, the clusters occur during supine REM sleep. Without CPAP, I do have a fair number of hypopneas when sleeping on my side, but you can see that it just takes a little pressure to eliminate those. When I'm congested, I do still get occasional isolated apneas on my side, even with CPAP. But the real action is on my back during REM sleep. Because any pressure over 10 gives me aerophagia, I now use the "tennis ball pinned to the nightgown" trick to avoid back sleeping entirely.

[leptic]

I'm pretty new myself so I have no expert commentary for you, but I can definitely say that you are not the only person with that pattern of long periods of normal breathing and then sudden clusters of frequent apneas. Check out this beauty of a night:

In my case, the clusters occur during supine REM sleep. Without CPAP, I do have a fair number of hypopneas when sleeping on my side, but you can see that it just takes a little pressure to eliminate those. When I'm congested, I do still get occasional isolated apneas on my side, even with CPAP. But the real action is on my back during REM sleep. Because any pressure over 10 gives me aerophagia, I now use the "tennis ball pinned to the nightgown" trick to avoid back sleeping entirely.

Thanks! I was trying to remember the last time I dreamed, but can't. I wonder if the interrupted REM sleep has anything to do with that? Scary to think some of us might have been walking around for years with little or no REM sleep...

[Julie]

You probably know what you're doing (certainly seem to understand some science), but I'm a little concerned about your DIY CO2 vent... do you think it really corresponds to the prof. ones that are on masks? And do you make sure it's not covered when you sleep?

[palerider]

Thanks! I was trying to remember the last time I dreamed, but can't. I wonder if the interrupted REM sleep has anything to do with that? Scary to think some of us might have been walking around for years with little or no REM sleep...

normally you don't remember dreams unless you're waked up during or very shortly after them.

you can dream in any sleep phase, not just rem.

[leptic]

You probably know what you're doing (certainly seem to understand some science), but I'm a little concerned about your DIY CO2 vent... do you think it really corresponds to the prof. ones that are on masks? And do you make sure it's not covered when you sleep?

You're probably right! (I have to keep reminding myself that a little knowledge is a dangerous thing). I've evaluated a lot of clinical and research systems for capnography at the hospital where I work. They all have pros and cons - the gas analyzer I'm using is a really high quality research grade system that would be too cumbersome for routine use on patients (and noisy - I kept it outside my bedroom). The FDA/Health Canada-approved systems used in hospitals are designed to be easy and robust to use while providing decent accuracy without frequent calibration.

Of course the analyzer will only give results as good as the placement of sampling port will permit - nasal cannulas are sometimes used but these can move around a lot and I tend to breathe mostly through my mouth. The sample port and mask I've used are as good as anything you'd get in a hospital, although we really designed the system to be used with inflowing air. I used a pediatric sized mask and removed the tubing and valves normally used to deliver gases to achieve the absolute minimum dead space. Normally the smaller mask would not seal well, but I used lots of Tegaderm to achieve a perfect seal (don't try this at home). All air inhaled and exhaled pass out of the large aperture at the front of the mask, into which I inserted the gas analyzer through a small hole that I drilled. During normal respiration this works great, but the process *depends* on respiratory movement of air in and out past the sampling port. It's debatable what the numbers will actually mean during an apnea, but the waveforms will definitely show an apnea very clearly.

The simple setup looks like this - it's quite comfortable to breathe through. I wasn't really worried about covering it up at night - the analyzer has a loud alarm that goes off if the sampling line is blocked (this one also has a very strong pump - for pulling air into the sampling line - that works quite well).



This is the analyzer, with my bed in the next room...



I would never ever use this stuff for critical patient care (well it would be illegal anyway), but for trying to gain some insight while I wait to get my test scored I'm hoping it's ok.

[leptic]

Thanks! I was trying to remember the last time I dreamed, but can't. I wonder if the interrupted REM sleep has anything to do with that? Scary to think some of us might have been walking around for years with little or no REM sleep...

normally you don't remember dreams unless you're waked up during or very shortly after them.

you can dream in any sleep phase, not just rem.

Weird - I always thought the more vivid/memorable dreams were supposed to occur in REM. Still, I used to remember some dreams sometimes - this hasn't happened in years.

[palerider]

Thanks! I was trying to remember the last time I dreamed, but can't. I wonder if the interrupted REM sleep has anything to do with that? Scary to think some of us might have been walking around for years with little or no REM sleep...

normally you don't remember dreams unless you're waked up during or very shortly after them.

you can dream in any sleep phase, not just rem.

Weird - I always thought the more vivid/memorable dreams were supposed to occur in REM. Still, I used to remember some dreams sometimes - this hasn't happened in years.

I'm pretty sure that's how it works, we all dream, every night, there's studies on what happens to people when they're prevented from dreaming, they go mad, literally. we just don't *remember* dreams, they're very ephemeral, unless we are waked up during or near the end of them.

[leptic]

they go mad, literally.

Hmmm. This is kind of how I've been felling for a while now...

[palerider]

they go mad, literally.

Hmmm. This is kind of how I've been felling for a while now...

ok, I think I confused "prevented from dreaming" with "prevented from sleeping" as to the going crazy bit... sorry..

but there's this on the subject of remembering dreams:
https://www.sciencedaily.com/releases/2 ... 085915.htm