Ok I don't get it....

[CelticRavenVA]

As some of you know, I had a thread not to long ago regarding larger tanks.

What we learned was, it doen't mater the amount of air you breath at depth it is how long you are at depth that contributes to the bends. ok.

What I am really not following is,

Ok I am at my safety stop, and breathing shallower to maintain my depth. If I am not breathing extreamly deeply where exactly is all this Nitrogen cooking out?

If I breath deep and am not swimming I will rise 10 feet, then decend 10 on the exhale... I had instructors say your breathing to deep, and exhaling to far. Ok, so now I adjust that for BC reasons, and what I am not understanding is does that increase your risk of DCI? The only thing I could come up with in my head that is carrying nitrogen out of my body is breathing, does breathing deeply or in this case not breathing deeply not effect this????

Edit: Ok maybe 10 feet is an a little over stated... but you get the idea...

Thanks,

 

[captain]

Shallow or deep breathing will not have any effect on the rate nitrogen comes out of solution or the amount. Just like breathing shallow or deep at depth will not affect nitrogen up take. Off gasing or up take of nitrogen to the blood is dependent on the pressure difference between the blood nitrogen tension and the lung gas nitrogen tension and the rate of blood flow. Faster blood flow will speed up the process and slower flow will slow the process. 1.3.9 The Indirect Effect of Pressure in the 1970 edition of the U S Navy diving manual would be good reading if you can find a copy. Maybe someone else can say where it is in the current manual.

Captain

 

[Dr Deco]

Hello CelticRaven:

Breathing

Many readers have asked similar questions over the years. The exchange of dissolved nitrogen in the body is dependant solely on the blood flow if all tissue nitrogen is dissolved and not in the free gas state. The breathing rate (= ventilation rate) will not affect the gas exchange unless it is very slow, something that would not really occur, because of carbon dioxide buildup.

Tissue Nitrogen Exchange

There are two factors that influence the loss of nitrogen (or helium) from the tissues. The first is the perfusion or blood flow to the specific tissue. The other factor is the “state” of the nitrogen (“phase state” is solid, liquid or dissolved, and gaseous). Nitrogen is either dissolved or in the form of a free gas in a bubbles. The gaseous nitrogen in a bubble exchanges very slowly as the nitrogen partial pressure is equal to the ambient pressure (plus some additional pressure from surface tension).

One always wishes to minimize the molecules of nitrogen in the gaseous state in a tissue (i.e., in microbubbles). One does this by slow ascents, and not producing nuclei in the first place. They are generated (probably) from musculoskeletal activity that results in hydrodynamic cavitation.

Dr Deco :doctor:

 

[CelticRavenVA]

Captain & Dr. D,

Wow, what would I do with you guys here! Makes sense, and is very intresting. So I guess breathing real deep hanging on the line there at my safety stop basicly did me nothing LOL. All that time I thought I was helping myself out.... Thanks again for the clarification there.