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I came looking into this topic because I have severe breathing issues that were caused as side-effects of neurofeedback that was supposed to help trauma issues. Ended up doing a lot of butekyo, but that didn't help me at all and wanted to know why. Somehow found out about this co2 stuff and saw the same issue about how expensive it was and how little people knew about it.
With lots of searching I found this meter about 2 years ago and have had it since: https://contechealth.com/collections/best-selling/products/contec-ca10s-end-tidal-co2-capnograph
As far as I can tell it seems reasonably accurate as the reading match what you would expect. As in breathing normal gives me values that are considered normal, and breathing too fast gives me the types of values you would expect for that.
Haven't been able to resolve my issues, but I was able to figure out more about what is occurring with it. My issue seems to be that my body thinks is a good idea to breath at crazy fast speeds from moving my body even just a little. I can for example breath at 30-60 breathes a minute just from typing quickly which will lead to feel awful really quickly, and similar results for other physical activities. Which will indeed mess up co2, but isn't the same issue people normally have so hence butekyo not helping.
Thank you, this is really fascinating! After writing this post, I talked to someone who does biofeedback using a capnometer, and they also mentioned that same CONTEC device as a cheap but still accurate capnometer. Their main gripe with it was that it responds more slowly compared to the CapnoTrainer and doesn't show the wave form, so it is not as good for doing biofeedback with (e.g. apparently the CapnoTrainer can show things like aborted breaths or weird exhalation patterns, whereas the CONTEC device can't show that), but it is still good enough for det...
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It could be using nonlinear optical shenanigans for CO2 measurement. I met someone at NASA using optical mixing and essentially using a beat frequency to measure atmospheric CO2 with all solid state COTS components (based on absorption of solar radiation). Technique was called optical heterodyne detection.
I've also seen some mid IR leds being sold, although none near the 10um CO2 wavelength.
COTS CO2 monitors exist for ~$100 and could probably be modified to messure breathing gases. They'll likely be extremely slow.
The cheapest way to measure CO2 concentration, although likely most inaccurate and slow, would be with the carbonic acid equilibrium reaction in water and a pH meter.
Ultimately the reason it's not popular is probably because it doesn't seem that useful. Breathing is automatic and regulated by blood CO2 concentration; I find it hard to believe that the majority of the population, with otherwise normal respiratory function, would be so off the mark. Is there strong evidence to suggest this is the case?
Thank you!
Does "COTS" stand for "commercial off-the-shelf" or is this some more technical acronym related to CO2 measurements?
Ultimately the reason it's not popular is probably because it doesn't seem that useful. Breathing is automatic and regulated by blood CO2 concentration; I find it hard to believe that the majority of the population, with otherwise normal respiratory function, would be so off the mark. Is there strong evidence to suggest this is the case?
I agree that this wouldn't be useful for the majority of the population. (Some breathing gurus cl...
The $100 CO2 monitors do not measure CO2, they measure VOCs, which in typical home and office settings closely correlates with CO2 (because humans emit both at a relatively constant rate and humans are the main sources of both in typical home and office settings).
I was not familiar with that term, but I am aware of sleep apnea and how that can lead to too-high levels of carbon dioxide. Like I said in a different comment, my current understanding is that both too-high and too-low are problems. In my case (and in other cases where people have anxiety-like shortness of breath) I think what's going on is too-low carbon dioxide. But having a capnometer seems useful for correcting both too-low and too-high carbon dioxide.
My understanding is that like many things, both low and high are bad (high carbon dioxide is called hypercapnia), so you want to be in the "good" range (I typically see 35-45 mmHg of partial pressure carbon dioxide being cited as the good range). In rationalist circles I have seen discussion of too-high atmospheric carbon dioxide being bad, but I am myself confused on how that connects to carbon dioxide levels in the blood (and separately, I'm not convinced that higher carbon dioxide levels in the air are bad either).
I typically see 35-45 mmHg of partial pressure carbon dioxide being cited as the good range
That's about 5% (since atmospheric pressure is about 760 mmHg) or 50,000 ppm. Being in a room with that high a concentration of co2 is immediately dangerous to life and health, which is a good illustration of the fact that this post (your post) is about co2 in exhaled air, which is distinct from co2 in inhaled air or ambient air, where for example 5,000 ppm of co2 "is the permissible exposure limit for daily workplace exposures" (source).
Too much is bad, too little is bad, it has a number of important functions, so that poisonous bit is a huge oversimplification that gets repeated a lot, but is clearly incorrect if you need some to be alive.
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What capnometry biofeedback is and why it seems important
A capnometer is a device that measures levels of carbon dioxide in your blood in a non-invasive way (think of it sort of like a pulse oximeter for carbon dioxide, except that the most common type of capnometer uses a nasal cannula to collect your breath instead of just clipping onto your finger). Capnometry biofeedback does biofeedback using a capnometer: you breathe while you are hooked up to a capnometer and looking at a monitor that tells you your carbon dioxide levels, and adjust your breathing style to try to get your carbon dioxide levels in the "good" range. You might even intentionally breathe in a "wrong" way to get carbon dioxide levels out of range, so that you can practice getting back into range. Over time (across multiple sessions), you learn what good breathing feels like, and automatically start to breathe in that way.
Certain health thinkers (e.g. Buteyko method practitioners) make a big deal out of carbon dioxide levels. They argue that low carbon dioxide levels (also known as hypocapnia) lead to a variety of health problems (shortness of breath, asthma, and much more).
My own impression is that while people like Buteyko practitioners often make wild claims, and the theory of why the method works is not known in much detail, the method does actually work (here is my own experience report). Having a capnometer seems useful for confirming that one's breathing (or other health) problems are due to carbon dioxide levels and for practicing better breathing. In my own experience trying nasal breathing/Buteyko-lite breathing without a capnometer, it feels like groping around in the dark, and I feel continually unsure if I am even doing the right thing (and also feel that my improvements have plateaued after just 2-3 months of experimentation); I imagine having a capnometer would feel like turning the lights on.
There are also a bunch of academic writing and even experimental studies on using a capnometer, but I have mostly not read these. My own interest and confidence in Buteyko-esque stuff/capnometry comes from my own experience playing around with such breathing techniques. (I realize this won't be convincing to many people. I'm just trying to be honest about my process for coming to this conclusion.)
Evidence for the assertion that capnometry biofeedback is not more widely known
I live in the Seattle area. In the last 1.5 years I have gone to two pulmonologists as well as one allergist-immunologist in the area, none of whom mentioned anything about carbon dioxide levels or capnometry or Buteyko breathing when I presented with shortness of breath. I have called a respiratory clinic in my area asking if they rented out any capnometers, and they did not even know what a capnometer was. I contacted my sleep doctor (with whom I did a sleep study, during which they did measure my carbon dioxide levels) asking if his office rented out capnometers and his office replied saying they did not, and that it is not a common practice to do so. I reached out to three biofeedback practitioners in my area asking if they used a capnometer in their practice; none of them did (one of them said they were familiar with how to use the device, but did not actually have one in their office).
Looking around online, I was able to find just a few people offering such services. The 20 that are listed on this page (most of them not even in the US), plus one in Texas and one in maybe Australia.
From the above I conclude that capnometry biofeedback is virtually unknown by the world.
Some guesses for why capnometry biofeedback is not more widely known
Here is my attempt to answer my own question. I can think of two reasons:
I am interested to hear thoughts on my reasons, or any other reasons people can think of.
Some discussion about why capnometers are so expensive
As best as I can make out, the chicken-and-egg problem where devices are expensive because not many people want them, and not many people want them because they're expensive, does not hold for capnometers. Hospitals seem to make use of capnometers (especially in emergency situations), so it is not just wacky quantified self/"pulmonaut"/mysteriously chronically ill people on the internet who want such devices. Also, capnometers don't seem to be inherently difficult to manufacture (although I know basically nothing about how to build one, so I am interested in hearing thoughts on this!). So why are they so expensive? It seems that there is a patent on one or more of the crucial components, so only one company is allowed to manufacture those components.
Samuel Kordik (who seems to have a lot of experience working in emergency medical services) on Twitter here says:
I was not able to find a "1)" in the replies. Not sure if the "2)" was a typo. I have also not fact-checked the comment so can't comment on its accuracy. I do not have experience looking up patent filings, and I expect it to take quite a bit of time to do this well, so I did not attempt it. Googling does produce a few filings, at least one of which has expired already, but I don't know if that's the most relevant patent. I would appreciate any help in trying to figure this out.
Muonium1 on this YouTube video:
I can't comment on the accuracy of the comment; I'd be interested in hearing people's thoughts!
LV Kusch comments in this Facebook thread:
Not very informative, but consistent with the above two quotes.
So here is a weak prediction I have: assuming non-expired patents really are the reason, this could mean that in the near future capnometers may become very cheap, allowing people to have easy access to do capnometry biofeedback and improve their breathing (and possibly other aspects of their health).
Acknowledgments: Thanks to Vipul Naik for feedback on a draft of this post!