minimum pO2 question.

[GLOC]

I have been following this thread and the bits about absorbtion of O2 within the lungs being possibly limited by other gases reminded me of the clips which are on the GUE Deco Malady DVD where they described the Atlantis Dive Series and how they took 'divers' on a dry dive to 2132 ft (~65 bar) in a chamber. During the 'dive' they took blood samples to see how the body was coping. In the DVD they also explained that the air was so thick that things would fall noticeably slower.

Duke Center For Hyperbaric Medicine And Environmental Physiology :: Photos :: Atlantis Dive Series Photos - Image of the IV work

[NotDeadYet]

Speaking with absolutely no medical background, I can't imagine there is a minimum fO2. Saturation divers work typically on a ppO2 of <0.5 to avoid chronic oxygen problems. That's fo2 of 3% at 150m or 5% at 90m.

[SteveGrr]

Originally Posted by Janos

Anyway, I think that as density increases, the mean free path of the moelcules will decrease, thus the chance of them hitting a wall (I remember that bit - ooh it's coming back. Integrate over d.Omega) should decrease. Therefore you don't absorb as much oxygen.
Janos

The density of the gas being breathed may have an effect, which is why I was speculating about breathing fluids, where the molecules in the fluid are more densely packed than in pressurised gas. For example:

Pulmonary gas exchange in dogs ventilated with hyperbarically oxygenated liquid

J. A. Kylstra, C. V. Paganelli, and E. H. Lanphier


J Appl Physiol, Vol. 21, Issue 1, 177-184, January 1, 1966


Seems to indicate that oxygen uptake from oxygenated fluids at 5bar is adequate, but CO2 clearance is deficient.