Breathing rate, air integrated computers and DCI correlation

[GrimSleeper]

"The volume of gas consumed ( ie breathing rate ) has absolutely no effect on the rate at which gas is dissolved in blood and thence tissue." Your quote I believe.

If you'd used square brackets and stuff it would even say you were quoting me...

And? The rate at which gas dissolves into tissues is driven by pressure (and gas solubility, if we're going to be fussy, but we're not talking about the diffusion rates of different gasses here), not volume of gas. The amount of gas passing through the lungs does not affect the rate at which gas dissolves into blood at the alveoli. Most of it just goes in and out.

There. I've said it again.

 

[beaverdivers]

Workload affects the amount of O2 metabolised and the amount of CO2 produced as a result. If workload is sufficiently high, it also affects the rate at which blood flows.

Correct.

The rate at which N2 is absorbed by tissues is driven by the pressure gradient between inspired ppN2 and tissue tension of N2. The greater the depth, the greater the pressure, the greater the inspired ppN2. Nitrox reduces the inspired ppN2 by decreasing the fraction of N2 in the breathing gas. The total amount of N2 absorbed is determined by pressure and time.

Correct.

The volume of gas consumed (ie the breathing rate) has absolutely no effect on the rate at which gas is dissolved into blood and thence tissue. The rate at which the blood is moving MIGHT very slightly affect the rate at which N2 is carried to tissues, but the speed with which N2 is getting into the blood in the lungs is still going to be by far the most important factor and that is entirely independent of how fast a diver is breathing or their heart is pumping. The amount of CO2 produced might have a very slight effect on efficiency of inert gas elimination and breathing efficiency in general.

Workload MIGHT be a factor. What if it is?

Breathing rate has absolutely nothing to do with DCS.

What if your theory is incorrect?

the fact that very little is understood about the mechanisms behind the problem - certainly not enough to formulate computer models that will make you safer by voodooing NDLs according to how fast you breathe.

You admit little is understood. What if you are wrong?

And claiming that it was a computer, rather than switching to air profiles on 32% (and almost certainly more conservative air profiles, at that) that prevented someone from further DCS events?

If a diver has a significant workload from respiration or heart rate, then the Uwatec air integrated dive computer will give the diver less No Stop time reducing their risk of the bends. If this theory is correct, the the diver has less risk. If not, they simply lose some Bottom Time.

If your theory is correct,the diver gets more Bottom Time. If it is incorrect, then they might get the Bends!

 

[JohnN]

Correct. Correct.Workload MIGHT be a factor. What if it is? What if your theory is incorrect? You admit little is understood. What if you are wrong?.

If your theory is correct,the diver gets more Bottom Time. If it is incorrect, then they might get the Bends!

And we might fall off the edge of the world because it is flat.

To re-quote TS&M. "The plural of anecdote is not data."

Do you have anything? (other than your opinion) I haven't seen you present any yet. . .

 

[GrimSleeper]

Correct. Correct.Workload MIGHT be a factor. What if it is? What if your theory is incorrect? You admit little is understood. What if you are wrong?If a diver has a significant workload from respiration or heart rate, then the Uwatec air integrated dive computer will give the diver less No Stop time reducing their risk of the bends. If this theory is correct, the the diver has less risk. If not, they simply lose some Bottom Time.

If your theory is correct,the diver gets more Bottom Time. If it is incorrect, then they might get the Bends!

My solution to the uncertainties is to not ride NDLs, employ a proper ascent strategy, and to use EAN on air profiles if I'm doing a lot of diving.

Yours is to use a computer which modifies a model which is already of uncertain accuracy in a manner which has no theoretical or empirical basis, or at least none you seem willing to provide.

My solution's cheaper, doesn't need batteries and relies on ideas which at least have some theoretical or empirical validation.

Your choice.


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[WB2GLP]

Actually, it is in post #1 of this thread:

"We had an older female diver get a "hit" after doing two long 50' - 60' dives in Cozumel. She had a long surface interval 1.5 hours. She was diving 21% O2."

Oh, yes. LONG is quite specific. My bad.

 

[beaverdivers]

Oh, yes. LONG is quite specific. My bad.

These dives were back in the late 90's. As I recall, they were about 60+ mins. each.

 

[scubadivingsteve]

Am I writing a thesis here? Ok I will play your condescending game. Prove to me that the technology discussed has never provided a margin of safety!

Bühlmann's models uncertain accuracy . No proof.

The information I provided was from the manufacturer of a product line that has been in production for 18 years. Yes this does not provide the empirical data you demand, it also hasn't produced a pile of dead bodies. While that doesn't prove success it does disprove failure. I'm sure the information that scubapro cites for this benefit is sales driven as is all product information.

My observations are based on 51 years of living are this. Volume or rate or however you wish to phrase it are directly proportionally to the amount of gas dissolved in blood. My empirical proof of this is irrefutable. You don't breathe you die. You breathe too fast you pass out. So the rate/volume is related. These examples are out of the normal respiration range which is what this thread was originally about. Fast shallow respiration, and DCS.

I changed my mind I am not playing your game any longer. I don't respect your opinion enough to care if you demand proof.

 

[tracydr]

Correct. Correct.Workload MIGHT be a factor. What if it is? What if your theory is incorrect? You admit little is understood. What if you are wrong?If a diver has a significant workload from respiration or heart rate, then the Uwatec air integrated dive computer will give the diver less No Stop time reducing their risk of the bends. If this theory is correct, the the diver has less risk. If not, they simply lose some Bottom Time.

If your theory is correct,the diver gets more Bottom Time. If it is incorrect, then they might get the Bends!

How in the world do you make a dive plan when the Uwatec computer changes your no-stop time based on workload?

 

[WB2GLP]

These dives were back in the late 90's. As I recall, they were about 60+ mins. each.

Last edited by beaverdivers; Today at 12:30 PM

Here is the message that has just been posted:
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These dives were back in 2008. As I recall, they were about 60+ mins. each.
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Good edit! Gotta' keep the story straight.

 

[ianr33]

My observations are based on 51 years of living are this. Volume or rate or however you wish to phrase it are directly proportionally to the amount of gas dissolved in blood. My empirical proof of this is irrefutable.

Let me make sure I understand this correctly.
You are stating nitrogen absorption is directly related to SAC. i.e breathe twice as much gas,absorb twice as much nitrogen? Does that mean that for 2 divers that weigh the same,if one has a SAC of 0.4 and the other a SAC of 0.8 ,then NDL times should be halved for the heavy breathing diver??