re abyss breathing fluids loss fs ece cmu edu doug loss writes besides the mechanical problems of moving so dense a medium in oan out of the lungs diaphragm fatigue etc is there likely to be a problem with the mixture i mean since the lungs never expel all the air in them the inhaled air has to mix pretty quickly with the residual air in the lungs to provide a useful partial pressure of oxygen right would this mixing be substantially faster slower at the pressures we re talking about there was an interesting article in scientific american some time ago about breathing liquid it was a few months before the abyss came out as far as i can remember they mentioned three things that were difficult to do at once with a substitute breathing fluid low viscosity if it s too difficult to force the fluid in out of the lungs you can t extract enough oxygen to power your own breathing effort let alone anything else diffusion rate obviously not all the air in your lungs is expelled when you breathe out and the part that isn t expelled is the part that s nearest the walls of the alveoli alveolus so the trip from the blood vessels to the new air has to be done by diffusion of the gas through the fluid apparently oxygen tends to diffuse more readily than co so even if you can get enough oxygen in you might not be able to get enough co out oxygen co capacity you have to be able to dissolve enough gas per unit volume oh and of course your new breathing fluid must not irritate the lungs or interfere with their healing or anything like that wim lewis wiml u washington edu
