Question Decreasing the Breathing Reflex....Possible?

[Dominik_E]

There surely are several effects. In the end, the "experiment" that was suggested above (static apnea time after pre-breathing O2) results in very significantly longer apnea times. Of couse in scuba diving we very often breath much higher ppO2 than on dry land, even when using air.

My basic point is that I doubt that in scuba diving these effects will result in the same dive lasting X minutes (with X being a substantial number) longer when using nitrox. Because for many divers, habitual breathing patterns will surely supersede the "breathing only when the urge comes". So delaying that urge by a bit more will not have a large real-life effect. But purely as an experiment, I would well believe that on nitrox, breath hold times would be prolonged.

 

[stiebs]

They also had this experimental liquid breathing technology in The Abyss. It worked there, so I don't why we haven't adopted in more widely in rec diving ..

 

[dmaziuk]

Because for many divers, habitual breathing patterns will surely supersede the "breathing only when the urge comes". So delaying that urge by a bit more will not have a large real-life effect.

Yes, but on scuba the "don't hold your breath" part would be a bit of a problem, wouldn't it?

There may be a paper in it: plot the breathholding times vs. the time and O2% pre-breathing different EAN mixes.

 

[Dominik_E]

Yes, but on scuba the "don't hold your breath" part would be a bit of a problem, wouldn't it?

Well that goes into the direction I am talking about. Just compare your breathing pattern right now, fully relaxed on land, with your pattern while fully relaxed during a dive. Very probably the two will be different. For a number of reasons. A lessened urge to breathe will only matter for gas consumption if people do not anyhow breathe long before that urge comes.

 

[Gelirfella]

Regardless. Lessening the urge by blunting the receptors is a terrible idea as it will lead to higher bicarbonate levels (actual compound which is significant here as CO2 mostly exists in this form in the blood) which will lower pH and have compounding downstream effects which will then be exacerbated by the inability to rapidly exchange CO2 at depth 2/2 increased gas density. In other words, it is a miracle that human lung physiology functions at depth and messing with said physiology is only going to exacerbate existing problems. It’s an interesting thought experiment, but reducing the urge to breathe is a fundamentally bad idea.

Rather, whoever came up with adding less dense gases to the mix is a real genius because it makes the most sense to augment human physiology at depth by reducing the ways in which increased pressure impairs an incredibly efficient system.

 

[Dominik_E]

Well we were considering the question in a scientific context, not if that is a good idea from a practical vewpoint. It does come up from time to time, and I personally think it has a rather clear answer: "In theory, yes that happens, but in practice normally one will not notice".

 

[Celt]

I’m not a doctor or scientist, but started yoga breathing at 16, and have worked deep on air. Divers are mouth breathing, oxygen bingers, along with a huge % of the population. How oxygen is used is the critical factor, not how much. Poor use of oxygen is what causes breathlessness and headaches, a feeling of not getting a sufficient breath.

 

[SlugLife]

This is a multitude of topics, depending on how you look at it. I'm going to focus mostly on reducing air consumption with SCUBA.

One of the best (and most expensive) ways to reduce air consumption is a rebreather! You can reuse (recycle) air, so you consume far less. Rebreathers aside....

Depth is a huge factor on open-circuit, so being shallower can definitely help extend dives. That aside, reducing CO2 generation is perhaps the next most important factor with air-consumption. The breathing-control itself would come after taht.

• Reduce or slow finning, pace yourself
• Streamline your gear, and reduce drag.
• Relax mentally and physically
• Avoid getting "out of breath" & slow down the instant you feel slightly "winded"
• Properly fitted gear (not inhibiting movement)
• take moderate-sized breaths in-and-out (not giant breaths)
• pacing your breathing rate, and being mindful of your rate.
• being comfortable - again with properly fitted gear, but also proper warmth.
• being in better physical shape can help a lot.

If that fails, there's also bigger or more scuba-tanks!

---

In terms of controlling the urge to breathe, free-diving might have some useful materials, though I know very little about free-diving.

 

[Dominik_E]

Sorry but that is diverging now! The question was not "How can a diver practically reduce air consumption?", and also not about gas densities, at least not to my reading. The question was for an explanation whether breathing pure oxygen (or nitrox) -- both happens inevitably e.g. during most decompression dives -- will decrease the urge for breathing.

That indeed happens, all else being equal the urge will come a bit later when breathing O2. But it will be hard to notice that in real dives, already because as said, in most situations breathing patterns will not be governed by the urge. I know that e.g. I do not notice a difference between air and EAN32 for very similar profiles in my own diving.

 

[Duke Dive Medicine]

Hello,
In fact, it does. Several other commentators on this thread have correctly pointed out that the most important influence on the drive to breathe is generated by carbon dioxide levels in the arterial blood - higher CO2 = greater drive to breathe. However, if you have a higher arterial oxygen level, then the drive to breathe generated by increasing CO2 levels is reduced. You can easily try this yourself if you have a cylinder of oxygen connected to a scuba regulator (oxygen clean of course!!). Time yourself holding your breath on air, and then try the same after washing oxygen into your lungs (eg 10 breaths on the scuba regulator). You will notice a significant difference in the time and the subjective perception of breath hold discomfort. To summarize this, although increasing CO2 level is the primary driver of breathing, this is definitely modified by oxygen levels (less drive to breathe is oxygen is high, more drive to breathe if oxygen is low).



Yes, this is essentially true although 'cold-pressed' is not really the right term. The lungs get compressed rapidly so even though the diver is apnoeic and consuming oxygen, the pressure of oxygen in the lungs increases during the rapid descent. We demonstrated the latter phenomenon in a 2021 study where we measured the arterial oxygen levels in an elite freediver at ~200' / 60m. The related paper has been published and can be read on PMC for free here.

Simon M

Simon, the paper is on apnea diving... what are your thoughts on respiratory rate/gas consumption as a function of inspired pO2 in compressed gas divers who breathe normally, i.e. don't artificially alter respiratory rate?