nitrogen and breathing

[diverrick]

My wife recently got OW Certified, and is doing great. One thing I have noticed is that she always has more air left at the end of the dives, then anyone else. She seems to be very conservitive in her breathing intake, volume or what ever you'd call it.
She thinks that because she dives using less air, in a given time line, that it must take longer to get rid of nitrogen afterwards. I say you have to breath in the nitrogen first, and the amount of ntrogen is directly proportional to the amount of air exchanged. Also, I think that the time it takes to rid of nitrogen after diving, the nitrogen would burn off no matter what she did under water. If she had more notrogen on board, then it'll take longer to get rid of it. Who's correct here?

 

[Dr Deco]

Hi diverrick:

Nitrogen Uptake

The amount of inert gas (nitrogen that you dissolve in your body is really basically a function of pressure. The deeper (and longer) you are underwater, the more nitrogen you will acquire. The breathing rate has really little to nothing to do with it per se. Sometimes a diver will breathe faster because s/he is working harder (swimming against a current, for example). When this is the case, the heart rate is fast and more blood is pumped to the tissues. This will result in increase nitrogen loading, but basically because of the blood flow. A diver who is nervous and breathes faster will take “on board” more nitrogen.

In addition, nitrogen is inert in the body and is eliminated by the blood to the lungs. It is not “burned up” in the body. Only oxygen is involved in a chemical reaction (unless you are a nitrogen-fixing bacterium).

Dr Deco :doctor:

Please note the next class in Decompression Physiology :grad:
http://wrigley.usc.edu/hyperbaric/advdeco.htm