how to breathe ??

[Hobbs]

well this is a serious medical question wich sounds pretty stupid at first glance..but since noone have been able to give me a proper answer before ill try it here

What is the proper way to breathe when offgassing ?
light or heavy ? or does it matter ?

I guess the real question is what portion of the offgassing and how much, relys on the amount of gass passing through the lungs ??

in extreme case this is what it comes down to.

if i take one breath on the safety stop or if i hyperventilate
how much is the difference in how much nitrogen I can offgass ?

hope someone understands the question.

this is a theoretical question and not a practical one.

in theory, theory and practice is the same
in practice its not

 

[BillP]

Hi Hobbs:

Gas exchange in the lungs is efficient enough that how you breath is not the rate-limiting-step in inert gas absorbtion or elimination. Breathe in and out enough to absorb the oxygen you need, eliminate excess carbon dioxide appropriately, and equalize your airspaces and you're breathing OK. The slow, even, reasonably deep breaths they taught you in your open water course should serve you well.

HTH,

Bill

 

[ScubaJorgen]

Yo

Gas exchange in the lungs takes place due to a gradient in partial pressure of Nitrogen. The partial pressure of nitrogen in the body is higher than the partial pressure of nitrogen in the lungs: nitrogen flows from the body to the lungs (and is breathed out).

If one stops breathing (kids, dont try this at home :nono: ) nitrogen flows from the body to the lungs, increasing the partial nitrogen pressure in the lungs. The gradient decreases, gas exchange rates become less. If eventually the gradient disappears, no more gas is exchanged.

Fortunately the diver breathes, and nitrogen is removed.

The question now is, how long has the diver hold his breath before the gas exchange is influenced noticably. If it is a few seconds, the diver should breath as much as he/she can. If it is an hour the diver should just breath.

The amount of gas in the in the lungs is about 5 liter (breathed in). If the amount of excess nitrogen in the body is 1 liter (which seems a lot to me) and to off-gas this amount normally takes one hour (which seems short to me) the amount of nitrogen which is exchanged per per breath of 5 seconds is 1 liter/(5 seconds*60 minutes) is around 0.003 liter. The normal lung capacity of 5 liter consisting of 79% nitrogen (air) is hardly influenced: during the breath the nitrogen fraction is raised from 79% to 79.06%.

For raising the Nitrogen level in the lungs by one procent one should breathhold about 1/(0.06/5sec)=80 seconds. I estimate the residual volume of the lungs when breathed out completely to be about 1 liter. When breathed out it would take 80 seconds *1 liter/5 liter = 16 seconds for the nitrogen fracture to raise 1%. Since these practices are not common practice during diving I agree with BillP :doctor:.

Note: every value mentioned in previous paragraphs is estimated by myself. They are not result of research.

Bye

Jorgen :doctor: