Air consumptions effect on nitrogen absorbtion

[Sheff diver]

Originally Posted by MattS

The blood is the transport mechanism. The gross offgassing capacity during a single circulation is propotional to the relative difference between arterial and venous PPN2. It's very significant.

More important is the relative difference between the venous blood and the tissue PPN2, surely. (remember we are not actually talking about PPN2 but degrees of saturation, but I guess PPN2 is a convenient, if inaccurate, way to refer to it)

Marcus

[Okeanos]

Mark Andrews states that he is less affected by a high PPO due to the fact he breathes so slowly, 1 breath per minute on his 156m air dive. If his PPO is affected so will his PPN.

Originally Posted by Divernet

Mark Andrews explains how it took several months of training to prepare for this dive. "As well as the physical there is the training of the mind over the body. I do a lot of yoga and free-diving exercises, which help with my breathing. On the surface I can lower my heartbeat to 32bpm. During the dive I breathe at a rate of one breath per minute, 30 seconds in and 30 seconds out."
I remember being told in my training that at depth the partial pressure of oxygen would be fatal. "That's only what the 'experts' reckon," says Mark. "I'm told that if my partial pressure of oxygen goes over three bar for more than four minutes I'll get an O2 hit. Says who, though, and based on what?
"There are no set rules, otherwise there'd be no record-breakers. Besides, I manage to minimise the PPO2 levels by using my breathing techniques."

But this is an exceptional case, in reality breathing normally, even as low as 3 breaths per minute you're PPN will remain constant and you will absorb as much nitrogen.

Even if it was lower, it would only be fractional, and for safety it is best to work on the standard absorbtion rate.

Where's Mark Chase when you need him? He'll tell us exactly.