RMV Spinoff from Accident & Incident Discussion - Northernone - aka Cameron Donaldson

[boulderjohn]

The rate at which you breathe by itself has no effect on on-gassing or off-gassing. If the rate at which you breathe is a result of increased physical effort, then that increased physical effort will also affect perfusion, and that will affect both on-gassing and off-gassing. But it is the increased perfusion that is causing it, not the rate of breathing.

 

[Dan]

Interesting info on how the O2 & CO2 exchange in your body during breathing:

 

[Celt]

I don't understand this. Oxygen to CO2 ratio would not change when you inhale through your mouth or your nose. If you breathe air, the O2 would be about 20.5% and CO2 would be about 0.04%.​

Light nasal breathing teaches the body to use oxygen more efficiently. Mouth breathing promotes over breathing which does the opposite. It’s not about the composition of the gas but how efficiently the body can use it. As an example people living at high altitudes use oxygen way more efficiently than people living at sea level.

 

[Celt]

The rate at which you breathe by itself has no effect on on-gassing or off-gassing. If the rate at which you breathe is a result of increased physical effort, then that increased physical effort will also affect perfusion, and that will affect both on-gassing and off-gassing. But it is the increased perfusion that is causing it, not the rate of breathing.

If you had two divers on the bottom doing the same workload the diver with greater oxygen efficiency and is breathing slow and light will incur less decompression penalty than the diver who is breathing heavily.

 

[Storker]

If you had two divers on the bottom doing the same workload the diver with greater oxygen efficiency and is breathing slow and light will incur less decompression penalty than the diver who is breathing heavily.

It seems as if science disagrees with you: Does higher RMV cause higher DCS risk?

 

[Celt]

It seems as if science disagrees with you: Does higher RMV cause higher DCS risk?

It’s not about the volume it’s about the individuals oxygen transfer efficiency, One diver is using oxygen efficiency and breathing light and the other is breathless, breathing heavily and actually exhaling large amounts of oxygen because of poor breathing habits.

 

[Storker]

It’s not about the volume it’s about the individuals oxygen transfer efficiency, One diver is using oxygen efficiency and breathing light and the other is breathless, breathing heavily and actually exhaling large amounts of oxygen because of poor breathing habits.

You're right that it isn't about the volume because there is no causal relationship between breathing rate and nitrogen loading. And if that's true (which it is), the diver who is is breathing slow and light will NOT incur less decompression penalty than the diver who is breathing heavily unless the difference in breathing rate is caused by differences in physical exertion.

And has been pointed out by others already, shallow breathing leads to poorer CO2 ventilation, increasing the risk of hypercapnia. I don't think you should advocate potentially harmful practices.

 

[Celt]

You're right that it isn't about the volume because there is no causal relationship between breathing rate and nitrogen loading. And if that's true (which it is), the diver who is is breathing slow and light will NOT incur less decompression penalty than the diver who is breathing heavily unless the difference in breathing rate is caused by differences in physical exertion.

And has been pointed out by others already, shallow breathing leads to poorer CO2 ventilation, increasing the risk of hypercapnia. I don't think you should advocate potentially harmful practices.[/QUOTE
Go back and read my post. I said similar work rate, the diver with a greater oxygen efficiency who is breathing slow and light because of a more effective oxygen transfer rate will incur less decompress penalty than an out of breath diver breathing heavily and there are large benefits for a diver who takes the time to improve their fitness and breathing technique.

 

[Dominik_E]

mac64, I think this is really not correct. Saturation and desaturation are driven by the gradient, not by the amount of gas available. The only thing that breathing rate can theoretically be relevant for is as an indirect measure of exertion, and thereby probably perfusion. More perfusion will lead to faster gas exchange, in and out. But you will not be able to change your deco obligation by changing breathing patterns.

 

[Celt]

mac64, I think this is really not correct. Saturation and desaturation are driven by the gradient, not by the amount of gas available. The only thing that breathing rate can theoretically be relevant for is as an indirect measure of exertion, and thereby probably perfusion. More perfusion will lead to faster gas exchange, in and out. But you will not be able to change your deco obligation by changing breathing patterns.

In no way am I advocating changing decompression practice or changing a dive schedule by bottom gas usage. I’m talking about loading the dice in your favor by practicing good breathing techniques ,improving your fitness level and oxygen efficiency. I may have some controversial ideas but I wouldn’t stick my neck out that far.